In my article ‘Ever wonder what caused your NET’, I concluded that currently, the only known scientifically explained causes for NETs were hereditary/genetic in nature. This is mostly associated with those who have MEN syndromes (yes, they are a syndrome not a type of tumour) and a few other less common types of NET including Pheochomocytoma/Paraganglioma (Pheo/Para) and Medullary Thyroid Carcinoma (MTC) (the familial version of MTC is often referred to as FMTC). However, please note this does not mean that all those diagnosed with pancreatic, parathyroid, pituarity, Pheo/Para and MTC tumours, will have any hereditary or genetic conditions, many will simply be sporadic tumors.
In recent years, it has become increasingly apparent that a number of Neuroendocrine tumours arise as a result of germline genetic mutations and are inherited in an autosomal dominant pattern. The number of genes implicated is increasing.
Apparently, 5-10% of Gastroenteropancreatic NETs (GEP NETs) are estimated to have a hereditary background. Hereditary syndromes associated with these include Multiple Endocrine Neoplasia (MEN), Von Hippel Lindau (VHL), Neurofibromatosis Type 1 (NF1), Tuberous Sclerosis (TS) and others. People who have a genetic condition may present with the tumors (perhaps along with an associated functional hormone syndrome) and so the genetic condition if there is one, may not be known at this point.
How will I know if I am affected?
Some people do worry about this, often because of what they find on the internet including inside patient forums. I suspect some people already know via family connections and as an example (there are many), I guess if you have 2 tumors found in (say) parathyroid and pancreas, it should at least raise a suspicion for MEN1 and be investigated.
Many people say how do I know, how do I check and this is obviously a delicate subject. Of course, your first port of call should be your NET specialist if you suspect or know of any connection.
Thus why I was interested in a paper published in Springer Link – titled “When should genetic testing be performed in patients with neuroendocrine tumours.” When reading, you’ll find it’s actually much more than that! Check it out here:
When should genetic testing be performed in patients with neuroendocrine tumours?
In this review, the authors examined the features which may lead a clinician to suspect that a patient may have an inherited cause of a NET and they outlined which underlying conditions should be suspected. They also discussed what type of screening may be appropriate in a variety of situations. If there is a way to identify which patients are likely to have a germline mutation, this would enable clinicians to counsel patients adequately about their future disease risk, and allows for earlier detection of at-risk patients through family screening. There’s a couple of minor errors in the text but I’ve contacted the authors who also agreed they should have included the pituitary.
The authors focused on presentations of NETs of the gastrointestinal system, chromaffin cell tumours (Pheochromocytoma and Paraganglioma) and Medullary Thyroid Carcinoma. Pituitary tumors (normally associated with MEN1), were not considered in scope for the review. Interesting thought, the review includes news of a move by endocrinologists to reclassify ‘Pituitary Adenomas’ as Pituitary NETs (PitNETs). Read the abstract here. This would appear to be in line with a gradual shift from the benign nomenclature associated with certain NETs to the ‘malignant’ potential of these type of tumors. The abbreviation is also in line with others, e.g. pNET, SiNET, etc. A useful reminder that we must stop using the term ‘Carcinoid‘ as this is regressing this extremely useful initiative to highlight the malignant potential of all NETs.
There also appears to be some linkage to the study looking at the possibility of familial Small Intestine NETs (SiNETs). You can read more about a US registered trial here (with apologies for use of the now defunct term ‘Carcinoid‘).
This is a complex subject and the text above is very basic. If you wish to dig further, the quoted reference is a good read. Just to emphasise, it’s aim is to provide advice about when to recommend genetic testing for NETs, and in doing so provides some useful reference information. Please also note they are finding new genetic links all the time so there could be some omissions of recently discovered genes but the article remains good enough as a primer on the subject. It’s broken down into 4 distinct tumor groupings:
On the day I was diagnosed, I hadn’t really thought about questions, the only one I actually remember asking was “how long do I have left to live” (I watch too many movies!). On the day of diagnosis and a period beyond, people tend to feel emotions of shock, denial, anger and sadness, before going on to accept their situation. Yes, I ‘googled‘ but not a great deal really – although some things I found did frighten me. I wish I had found this article way back then.
As things progressed in the weeks after ‘D-Day’, I started to work out the sort of things to ask but even then it was limited. I had been referred to an experienced NET team so I felt confident they would do whatever needed doing. In hindsight, I can now think of a quite a few questions I should have asked. That said, I suspect my team probably gave me the answers without having been asked the questions!
My blogging efforts have turned into a ‘Community’ of sorts. Consequently, I’m contacted daily from people finding me on the web. Many of these people are at the pre-diagnosis or initial phase. Many are undiagnosed. Most are looking for information and some sound like they are already at the ‘acceptance stage’; some are frightened about the future, some are angry because they think they are not being told important information and some also feel they have been messed about or ‘fobbed off’ by their doctors. Of course I’m happy to help but only after reminding them that I’m just a wee Scottish guy with the same disease!
I have to say that some people arrive on my site without a diagnosis but often seem to be very well prepared – the power of the internet I suspect. The questions I mostly get involve finding experts and then what questions to ask them.
As an extra bonus to this post, I offer you a starting point for the best places I know for finding NET expertise:
One US center is now the first to achieve a European NETs Center of Excellence accreditation – read more hear about University of Iowa Holden Comprehensive Cancer Center – click here
NANETS have listed “NET Centers” here – NANETS NET Centers and Clinics
The NET Research Foundation as they also have a ‘Doctor Database’ section which differs slightly from CCF below.
Dr. Shereen Ezzat at Princess Margaret in Toronto (PMH)
Dr. McEwan, The Cross Clinic, Alberta?
Dr Kavan at Montreal Jewish General Hospital (Oncology)
Dr Buteau / Beauregard at Quebec Hotel Dieu (Radiation Oncology (PRRT, Ga68)
Dr Rivera at Montreal General Hospital (Endocrinology)
Dr Metrakos at the Montreal Royal Victoria Hospital (Surgeon) sees a lot of NET patients
On the French side Dr Andre Roy at the CHUM in Montreal (surgeon) also sees a lot of NET patients
Dr. Jamil Asselah also treats net patients. He is an oncologist….Quebec
Michael Sawyer at Cross Clinic in Alberta Edmonton.
Drs. Parkins, Card, and Paseka at the Tom Baker CC in Calgary.
London Ontario: Dr. David Laidley, Dr. Robert Reid in the Neuroendocrine Clinic at London Regional Cancer Program and Dr. Daryl Gray, Surgeon.
Russia – Clinical Oncology Research Institute, N. N. Blokhin RCRC RAMS, Address: 24, Kashirskoye sh., Moscow, 115478, RF. NET specialist Alla Markovich
In my Group – ask other patients: Click here to join.
Neuroendocrine Cancer – 10 questions to ask your specialist
Many people ask me what sort of questions to ask and because NETs is such a diverse bunch of diseases, that leads to me ask them a series of questions to ascertain what they might consider asking. I’m not surprised to find some are unable to answer my questions and so those then become some of their questions to ask!
Also, questions don’t end at the diagnosis phase, they continue and in fact, some of the answers to the questions below, may bring up new questions in your mind. Some of these questions can be asked time and time again in the event of issues downstream.
If you’re currently confused about the essential facts of your condition, you’re not alone. In a recent study, almost half of cancer patients did not know basic stuff such as grade and stage of cancer, and after their initial treatment, whether they were free of disease or in remission.
For those entering or are recently just beyond the diagnostic phase, you may find certain questions cannot yet be answered without further test results etc. However, if the answer is not yet known for whatever reason, at least you have it on your list for follow up appointments. Consequently, I’ve constructed this list of questions that should function as a generic set. There may also be ‘specific to country’ questions such as insurance cover in addition to this suggested list. Of course, some of you may not want the answer to so certain questions. That’s perfectly understandable, so don’t ask!
1. Where is my primary tumour and what type of NET is it?
This is a fundamental question and it’s likely many will already have some inkling about location and perhaps a type. The difference between NETs and other types of cancer is the primary can be found wherever there are Neuroendocrine cells rather than a specific part of the anatomy in terms of naming the type of cancer, i.e. a NET of the pancreas is not Pancreatic Cancer.
The type of NET is key as it will drive a lot of other stuff including treatment. Location and type of NET are not always aligned, for example, you may have a NET in your Pancreas but there are several types of Pancreatic NET (or pNET) and these may depend on identification of a particular hormone (see syndrome below). Many NETs are non-functional (there is no oversecreting hormone).
For some the primary will not yet be found (i.e. cancer of unknown primary or CUP). There may also be multiple primaries.
2. What is the grade and differentiation of my tumour(s)?
Another fundamental question as this defines the aggressiveness of the disease and is absolutely key in determining overall treatment plans. Treatment plans for poorly differentiated can be very different from well differentiated. Read more here – Grading and here – Benign or Malignant
3. What is the stage of my disease?
Fundamental to understanding the nature of your disease. Stage confirms the extent of your disease, i.e. how far has it spread. Again this will drive treatment plans and long-term outlooks. Scans are really important in determining the Stage of your cancer – check out my scans post here. Read more here on Staging
4. Do I have a NET Syndrome?
Many NET patients will have been experiencing symptoms prior to diagnosis, perhaps for some time. It’s possible these symptoms form part of what is known as a ‘Syndrome’ and there are several associated with NETs. Syndromes are mostly caused by the effects of over-secretion of hormones from the tumours, a hallmark of Neuroendocrine disease. Carcinoid Syndrome is the most common but there are many more depending on the primary location. Read more here – NET Syndromes.
5. What is my treatment plan, and what are the factors that will influence my eventual treatment? When will I start treatment
This is a very complex area and will depend on many factors. Thus why your specialist may not have the answers to hand. Decisions on treatment are normally made by some form of Multi-disciplinary Team (MDT). Many people diagnosed with cancer expect to be whisked away to an operating theatre or chemotherapy treatment. However, for many this is not what actually happens. Depending on what testing has been done up to the actual diagnosis, it’s possible that even more testing needs to be done. Additionally, for those with an accompanying syndrome, this will most likely need to be brought until control before certain treatments can be administered; and even then, there may be checks to make sure the treatment will be suitable. Sometimes it’s a case of ‘Hurry up and wait’. My first treatment was 6 weeks after diagnosis and that was designed to control my syndrome ready for surgery which was undertaken 14 weeks after diagnosis. It’s also possible you will be placed on a ‘watch and wait’ regime, at least to begin with.
6. Can you comment on the potential for my type of NET to be related to any familial or genetic aspects of cancer?
A small percentage of NETs are hereditary/genetic in nature. This is mostly associated with those who have Multiple Endocrine Neoplasms (MEN) syndromes and a few other less common types of NET including Pheochomocytoma / Paraganglioma(Pheo/Para) and Medullary Thyroid Carcinoma (MTC) (the familial version of MTC is often referred to as FMTC). However, please note this does not mean that all those diagnosed with pancreatic, parathyroid, pituitary, Pheo/Para and MTC tumours, will have any hereditary or genetic conditions, many will simply be sporadic tumors.
7. Will you be able to get rid of all my disease?
This is a really difficult question for any specialist, even a Neuroendocrine expert. All published articles on NETs will say they are a heterogeneous collection of diseases (i.e. consisting of dissimilar entities) which makes this question (and others) difficult. I have read articles written by the world’s foremost NET experts and they all have the word ‘curative’ mentioned in various places. So I guess in particular scenarios with certain NETs, and if the disease is caught early enough, that possibility exists. However, for many, the disease could be incurable, particularly where there is distant metastasis. But, the disease has many treatment options for most types and for many it is possible to live as if it were a chronic condition. I call it ‘incurable but treatable’. Read more here – Incurable vs Terminal
8. What Surveillance will I be placed under?
Again, this is very individual in NETs and is mainly dependent on type of NET, grade and stage and how the patients reacts to treatment. This may not be known until you have undergone your initial treatment. For example, surveillance scans can be any period from 3 months to 3 years depending on tumour type(location) and stage/grade. Marker testing tends to average around 6 monthly but could be more or less frequently depending on what’s going on. Read more here – click here
9. Will I receive support and specialist advice after my treatment?
Let’s not be afraid of the word ‘Palliative’, it does not always mean ‘end of life’ care. Another example is nutrition. Many people with NETs, the condition in combination with the side effects of treatment may necessitate an alteration of diet and this is a very individual area. I would also emphasise that dietitians not well versed in NETs might not offer the optimum advice. Read more – My Nutrition Series.
10. How will treatment affect my daily life?
This is a question that many people miss but it’s becoming more important as we all live longer with cancer Again, this may not be possible to answer immediately but perhaps this question could be reserved once you know which treatment(s) you will be receiving. All treatment comes with side effects and can last for some time or even present with late effects after some years. The ‘consequences’ of cancer treatment need to be factored in earlier so that the necessary knowledge and support can be put in place. See also Unmet Needs for NET Patients
I suspect others will have suggestions for this list so feel free to submit these to me. I quite often refresh my posts over time.
I spend a lot of time talking about the most common forms of Neuroendocrine Tumours (NETs), but what about the less well-known types? As part of my commitment to all types of NETs, I’d like to shine a light on two less common tumour types known as Pheochromocytomas and Paragangliomas – incidence rate approximately 8 per million per year. They are normally grouped together and the definitions below will confirm why. If you think it’s difficult to diagnose a mainstream NET, this particular sub-type is a real challenge.
So, let’s get definitions out of the way:
Pheochromocytomas (Pheo for short)
Pheochromocytomas are tumours of the adrenal gland that produce excess adrenaline. They arise from the central portion of the adrenal gland, which is called the adrenal medulla (the remainder of the gland is known as the cortex which performs a different role and can be associated with a different tumour type). The adrenal medulla is responsible for the normal production of adrenaline, which our body requires to help maintain blood pressure and to help cope with stressful situations. The adrenal glands are situated on top of the kidneys (i.e. there are two). Adrenaline is also called ‘epinephrine’ which is curiously one of the 5 E’s of Carcinoid Syndrome.
Paragangliomas (Para for short)
Paragangliomas are tumours that grow in cells of the ‘peripheral’ nervous system (i.e. the nerves outside the brain and spinal cord). Like Pheochromocytomas, they can release excess adrenaline. There can be confusion between the two types of tumour as Paragangliomas are often described as extra-adrenal Pheochromocytomas (i.e. a Pheo external to the adrenal gland).
Going forward, I’m going to talk about both using the single term of ‘Pheochromocytoma’ in the context of an adrenaline secreting tumour but may refer to Paraganglioma where there might be a difference other than anatomical location.
Pheochromocytomas are often referred to as the “ten percent tumour” because as a rule of thumb they do many things about ten percent of the time. However, these figures are slowly changing, so this label is gradually becoming less apparent. The following is a fairly exhaustive list of these characteristics:
A few facts about Pheochromocytomas
As much as 1 in 3 are Malignant but most have undetermined biologic potential. A recent document issued by the World Health Organisation (WHO) stated that “Paragangliomas should not be termed benign”.
Around 10% of Pheochromocytomas are Bilateral (i.e. found in both adrenal glands: 90% arise in just one of the two adrenal glands)
Around 10% are Extra-Adrenal (found within nervous tissue outside of the adrenal glands … i.e. 10% are Paragangliomas)
Around 10% are found in Children (i.e. 90% in adults)
Up to 30% are Familial potentially rising to 50% for metastatic cases and Multiple Endocrine Neoplasia (MEN) involvement.
The recurrence rate is around 16%, i.e. about 1 in 6 patients have a tumor that comes back after surgery. Tumors that come back also have the potential to be malignant. If you have pheo or para and have surgery to remove it, be sure to continue to check in with your doctor to monitor for any returning tumors.
Present with a stroke (10% of these tumours are found after the patient has a stroke)
The classic symptoms of Pheochromocytomas are those attributable to excess adrenaline production. Often these patients will have recurring episodes of sweating, headache, and a feeling of high anxiety.
Headaches (severe)(one of the classic triad, see below)
Excess sweating (generalized)(one of the classic triad, see below)
Racing heart (tachycardia and palpitations)(one of the classic triad, see below)
Anxiety and nervousness
Nervous shaking (tremors)
Pain in the lower chest or upper abdomen
Nausea (with or without vomiting)
According to the ISI Book on NETs (Woltering, Vinik, O’Dorisio, et al), Pheochromocytomas present with a classic triad of symptoms and signs: headache, palpitations and sweating. This symptom complex has a high specificity and sensitivity (>90%) for the diagnosis of Pheochromocytomas. The figure is much lower in individual symptom presentations (palpitations 50%, sweating 30%, headaches 20%). In addition to correctly diagnosing from these symptoms, Pheochromocytomas may also be found incidentally during a surgical procedure even after a diagnosis of an ‘adrenal incidentaloma’
Markers. Like serotoninsecreting tumours, adrenal secreting tumours convert the offending hormone into something which comes out in urine. In fact, this is measured by 24 hour urine test very similar to 5HIAA (with its own diet and drug restrictions). It’s known as 24-hour urinary catacholamines and metanephrines. This test is designed to measure production of the different types of adrenaline compounds that the adrenal glands make. Since the body gets rid of these hormones in the urine, we simply collect a patient’s urine for 24 hours to determine if they are over-produced. Like 5HIAA, there is also a plasma (blood draw) version of the test. According to the ISI Book on NETs, there is also an additional test called ‘Vanillylmandelic Acid (VMA). This reference also indicates the most sensitive test is plasma free total metanephrines. Also read more here.
Genetics. The familial connection with Pheo/Para is complex. Up to 13 genes have been identified including NF1, RET, VHL, SDHA, SDHB, SDHC, SDHD, SDHAF2(SDH5), TMEM127, MAXm EPAS1, FH, MDH2. Read more here ( recent update). The NIH also have a useful section –click here.
Scans. Other than the usual range of scanners, ultrasound, CT/MRI, all of which may be used to find evidence of something, the other scan of note is called MIBG. This is a nuclear scan similar in concept to the Octreotide Scan given to many NET patients (in fact some Pheo patients my get an Octreotide scan if they have somatostatin receptors). The key differences with MIBG is the liquid radioactive material mix which is called iodine-123-meta-iodobenzylguanidine or 131-meta-iodobenzylguanidine (this is where the acronym MIBG originates). Together with the markers above, the results will drive treatment. Depending on availability, the latest PET scans may also be available potentially offering greater detail and accuracy i.e. 18F-FDOPA, 18F-FDG and Ga68. Read more on scans here.
This statement and diagram was provided by Dr Mark Lewis who is an Oncologist and MEN patient. “The algorithm for working up a hyperadrenergic state is attached (and was developed by Dr. Young at Mayo Clinic). It outlines the most reliable testing for a pheo or Paraganglioma”
Additional Factors and Considerations
This is an awareness post so I’m not covering treatment options in any detail except to say that surgery if often used to remove as much tumour as possible. Somatostatin Analogues may also be used in certain scenarios in addition to other hormone suppression or symptom controlling drugs. That said, Pheo/Para patients may be interested in a PRRT trial exclusively for Pheo/Para – read more here (see section entitled – “What about Pheo/Para”)
The adrenal cortex mentioned above is actually the site for Adrenocortical Carcinoma (ACC) – this is a totally different cancer.
Pheochromocytomas are probably difficult to diagnose (you only have to look at the symptoms to see that). The differential diagnoses (i.e. potential misdiagnoses) are: hyperthyroidism, hypoglycaemia, mastocytosis, carcinoid syndrome, menopause, heart failure, arrhythmias, migraine, epilepsy, porphyria lead poisoning, panic attacks and fictitious disorders such as the use of cocaine and benzedrine.
Many Pheochromocytoma patients will also be affected by Multiple Endocrine Neoplasia (MEN), in particular MEN2 (there are some wide-ranging percentage figures online for this aspect). There can also be an association with Von Hippel-Lindau (VHL) syndrome and lesscommonly with Neurofibromatosis type 1.
Given the nature of the hormones involved with Pheochromocytomas, there is a risk of intraoperative hypertensive crises. This is similar in some ways to Carcinoid Crisis but needs careful consideration by those involved in any invasive procedure.
Newly Approved Drug – AZEDRA
On 30th July 2018, Progenics Pharmaceuticals Announces FDA Approval for AZEDRA® (iobenguane I 131) to Treat Unresectable, Locally Advanced or Metastatic Pheochromocytoma or Paraganglioma – read more by clicking here.
Pheochromocytomas are very complex involving many of the challenges found in the more abundant and common types of NETs. To underscore this statement, please see this case studywhere one patient was misdiagnosed with psychiatric problems for 13 years before being correctly diagnosed with a metastatic Pheochromocytoma.
This is an extremely basic overview offered as an awareness message about the lesser known types of NETs. I refer you to my disclaimer. If you wish to learn more about Pheochromocytomas and Paragangliomas, check out the links below.
We’ve all heard the age-old question about the chicken and the egg? Scientists claimed to have ‘cracked’ the riddle of whether the chicken or the egg came first. The answer, they say, is the chicken. Researchers found that the formation of egg shells relies on a protein found only in a chicken’s ovaries. Therefore, an egg can exist only if it has been inside a chicken. There you have it!
On a similar subject, I’m often confused when someone says they have been diagnosed with ‘Carcinoid Syndrome’and not one of associated ‘Neuroendocrine Tumours’. So which comes first? I guess it’s the way you look at it. In terms of presentation, the syndrome might look like it comes first, particularly in cases of metastatic/advanced disease or other complex scenarios. Alternatively, a tumour may be found in an asymptomatic patient, quite often incidentally. However, on the basis that the widely accepted definition of Neuroendocrine Tumours would indicate that a syndrome is secondary to tumour growth, then the tumour must be the chicken.
I sometimes wonder what patients are told by their physicians….. or perhaps by their insurance companies (more on the latter below). That said, I did see some anecdotal evidence about one person who was diagnosed with Carcinoid Syndrome despite the lack of any evidence of tumours or their markers. This might just be a case of providing a clinical diagnosis in order to justify somatostatin analogue treatment but it does seem unusual given that scientifically speaking, Carcinoid Syndrome can only be caused by a particular type of NET.
I have a little bit of experience with this confusion and it still annoys me today. Shortly after my diagnosis, I had to fill out an online form for my health insurance. The drop down menu did not have an entry for Neuroendocrine ‘anything’ but I spotted Carcinoid only to find it was actually Carcinoid Syndrome. By this stage I had passed the first level of NET knowledge and was therefore suspicious of the insurance company list. I called them and they said it was a recognised condition and I should not worry. Whilst that statement might be correct, I did tell them it was not a cancer per se but an accompanying syndrome caused by the cancer. I added that I was concerned about my eligibility for cancer cover treatment and didn’t want to put an incorrect statement on the online form. However, they persisted and assured me it would be fine on that selection. On the basis it was really the only option I could select, I selected and submitted. I did get my cover sorted. However, it’s now clear to me that their database was totally out of date. A similar thing happened when I was prescribed Octreotide and then Lanreotide, the only ‘treatment type’ they could find on their database was ‘chemotherapy‘ – again their system was out of date. I’m told by someone in the know, that individual insurance companies are not responsible for this list, they all get it from a central place – I’d love to pay that central place a visit!
I quickly thought about all the other NET Syndromes for their ‘chicken and egg’ status! Pancreatic NET (pNET) Syndromes must all be ‘chicken’ given the tumour definition and the secretion of the offending hormones that cause these other syndromes e.g. Insulin, Gastrin, Glucagon, Pancreatic Polypeptide (PP), Vasoactive Intestinal Peptide (VIP) and Somatostatin, etc.
All of that said, the exception might be hereditary syndromes e.g. MEN (yes it is a syndrome, not a tumor type). MEN syndromes are genetic conditions. This means that the cancer risk and other features of MEN can be passed from generation to generation in a family. A mutation (alteration) in the various MEN genes gives a person an increased risk of developing endocrine/neuroendocrine tumors and other symptoms of MEN. It’s also possible that the tumors will be discovered first. It’s complex as you will see in my article entitled “Genetics and Neuroendocrine Tumors”.
In 2013, just when I thought everything seemed to be under control, I was told I had a ‘lesion’ on the left upper lobe of my thyroid. At the time, it was a bit of a shock as I had already been subjected to some radical surgery and wondered if this was just part of the relentless march of metastatic NET disease. The thyroid gland does in fact get mentioned frequently in NET patient discussions but many of the conversations I monitored didn’t seem to fit my scenario – cue relentless study! I’ve been meaning to write this blog for some time but here is a synopsis of my research translated into ‘patient speak’. This is intentionally brief, it’s a big subject. I’ll finish off with an update on where I am with my thyroid issue.
Where is the thyroid and what does it do?
Before I found out about my thyroid problem, I had absolutely no idea what its function was. I can tell you know, it’s a small organ but it has a massive job!
It lies in the front of your neck in a position just below your ‘Adam’s apple’. It is made up of two lobes – the right lobe and the left lobe, each about the size of a plum cut in half – and these two lobes are joined by a small bridge of thyroid tissue called the isthmus. It is sometimes described as butterfly shape. The two lobes lie on either side of your wind-pipe. The fact that it comes up a lot in NET patient discussions is hardly surprising as it’s an endocrine organ responsible for making two hormones that are secreted into the blood: Thyroxine (T4) and Triiodothyronine (T3). These hormones are necessary for all the cells in your body to work normally.
Do I have Thyroid Cancer?
I’ve had a number of biopsies on the thyroid lesion, several fine needle aspiration (FNA) and one ‘core’. The FNAs were generally inconclusive and the core confirmed fibrous tissue only. However, the general diagnosis is inconclusive and I have been labelled “THY3F”. Curiously this decodes to “an abnormality is present but it could either be a benign (non cancerous) growth or a malignant cancerous growth of the follicular cells. A quick primer on Thyroid Cancer is below if you’re interested.
It’s easy to worry about irregularities showing up on scans if you have NETs. Take the thyroid for example, the Ga68 PET has a habit of ‘lighting up’ thyroids – this is a worry because it’s an endocrine organ; and there is a type of thyroid NET (not forgetting the parathyroid), and NETs have a habit of metastasizing to strange places. Sure, you should get it checked out when this happens, but while you will only hear about the outliers on social media, statistically, the vast majority of thyroid nodules are benign. We know about ours because we get so many scans but many people will probably never know and will probably never be bothered by them either. When you look at the figures below, it becomes clear that many NET patients are going to have a thyroid nodule regardless of their diagnosis.
The following is a list of facts regarding thyroid nodules:
Thyroid nodules are three times more common in women than in men
30% of 30-year-old women will have a thyroid nodule.
One in 40 young men has a thyroid nodule.
More than 95% of all thyroid nodules are benign (non-cancerous growths).
Some thyroid nodules are actually cysts, which are filled with fluid rather than thyroid tissue.
Purely cystic thyroid nodules (thyroid cysts) are almost always benign.
Most women will develop a thyroid nodule by the time they are 50 years old.
The incidence of thyroid nodules increases with age.
50% of 50-year-old women will have at least one thyroid nodule.
60% of 60-year-old women will have at least one thyroid nodule.
70% of 70-year-old women will have at least one thyroid nodule.
Fear of spread
It’s easy to be concerned about irregularities showing up on scans if you have NETs. However, the Ga68 PET has a habit of ‘lighting up’ thyroids and this is a double worry because it’s an endocrine organ, and there is a type of thyroid NET (not forgetting the parathyroid). But it eventually became clear through research that most are unconnected. Sure, you should get it checked out, but while you will only hear about the outliers on social media, the vast majority of cases are benign. If you constantly fear cancer spread with every single issue you undergo as a human being, you probably need some help. You may therefore find my ‘fear’ articles a useful read plus there are two videos presented by professionals who help caner patients cope with these issues:
Thyroid overdiagnosis and overtreatment. You can find many medical papers confirming that incidence of thyroid tumour diagnosis has increased dramatically in many countries in the developed world over the past three decades. Papillary thyroid cancer, which has been responsible for virtually the entire increase, is rarely lethal. The 20 year survival rate is greater than 90%, and approaches 100% for the smallest cancers. The increasing incidence is most likely due to overdiagnosis—the detection of subclinical cancers never destined to cause harm. This conclusion has been reached because the incidence has been primarily due to the detection of small papillary cancers, mortality due to thyroid cancer has not changed significantly, and small foci of papillary thyroid cancer are commonly found at autopsy in people who died of other causes. Overdiagnosis is a problem because it exposes people to the potential side effects of treatment, but without an equal expectation of benefit, because the cancer is unlikely to advance. We know about ours because we get so many scans.
Issues above the diaphragm
There can be other issues with Thyroids including cancer and clearly this was my concern when the word ‘lesion’ was mentioned. At this point, it’s worth mentioning something from my cancer history which I initially assumed was related but it would appear to be a coincidence (for the time being …..). When I say “above the diagphragm”, I mean above the abdoment in the general neck and chest area. I also have a hotspot in my left supraclavicularfossa (SCF) lymph nodes (near the clavicle), geographically close to the thyroid (and my lesion is left-sided). 5 nodes were removed from this area in Feb 2012 for an exploratory biopsy which subsequently tested negative and CT and Ultrasound both show nothing vascular or pathologically enlarged. BUT …. there is still a hotspot showing on a subsequent Octreoscan and Ga68 PET since the nodes were removed in 2012. For the record, I also had positively tested nodes removed from my left axillary (armpit) during the same procedure (my distant disease has always been left-sided).
The surgeon who operated on my left axillary and SCF nodes also specialises in Thyroids and so it was an easy decision to ask to be referred to him. He explained that whilst he could just take the left lobe or the whole thyroid, it would mean lifelong treatment to add to my current burden and perhaps for something which will never trouble me. As nothing is palpable and I have no symptoms, I agreed to a ‘watch and wait’ approach. I now have regular tests and I saw him Endocrine MDT annually for a blood test review and ultrasound check (but see update below).
See EndocrineWeb for more detail about thyroid issues unrelated to NET.
Latest update as at 15 Jan 2019
After monitoring for the first two years, my specialist was not happy with TSH/T4 blood results (elevated for the second time and also on a retest). On 20 March 2018, following an Endocrine appointment, I was put on a trial dose of 50mcg of Levothyroxine to counter the thyroid panel results indicating mild hypothyroidism. Levothyroxine is a thyroid hormone replacement. My subsequent two x thyroid panel results are back in the middle of the range so all is good. Am detecting a slight increase in available energy.
The results of my first Ga68 PET scan in June 2018 indicated some “uptake” but the report inferred it was physiological uptake (false positive). In fact, at my 2019 appointment, the thyroid lesion is slightly smaller on the latest ultrasound. I’m personally fairly certain this is not connected to NETs and my Endocrine MDT have now referred me back to be survellanced by the NET MDT, they remain on call for any issues.
What else can go wrong with a thyroid?
Apart from cancer, the main issues appear to be an underactive Thyroid or an overactive Thyroid – known respectively as Hypothyroidism (not enough thyroxine is produced for the body’s needs) and Hyperthyroidism (too much thyroxine is produced for the body’s needs). Of course, these issues can be caused or made worse by cancer.
Hypothyroidism – If too little of the thyroid hormones are produced, the cells and organs of your body slow down. If you become hypothyroid, your heart rate, for example, may be slower than normal and your intestines work sluggishly, so you become constipated. Key symptoms: tiredness, feeling cold, weight gain, poor concentration, depression. Some of these symptoms look familiar? The word ‘hashimoto’s’ also comes up on patient forums frequently – this is related to hypothyroidism (underactive).
Hyperthyroidism – If too much of the thyroid hormones are secreted, the body cells work faster than normal, and you have Hyperthyroidism. If you become hyperthyroid because of too much secretion of the hormones from the thyroid gland, the increased activity of your body cells or body organs may lead, for example, to a quickening of your heart rate or increased activity of your intestine so that you have frequent bowel motions or even diarrhoea. Key symptoms – weight loss, heat intolerance, anxiety, and, sometimes, sore and gritty eyes. Hmm, again, some of these look familiar?
Check out this excellent short video fromWebMD – click here. It’s based on USA but most of it is relevant globally.
It’s also worth noting thatsomatostatin analoguesmight cause a “slight decrease in Thyroid function” (it actually states words to this effect in the Lanreotide and Octreotide patient leaflets). Thus why I advise you not to be underactive with your Thyroid surveillance – read more click here
Routine ‘Thyroid blood tests’ from your doctor will confirm whether or not you have a thyroid disorder. I now test for TSH (thyroid-stimulating hormone), T3 and T4 every 6 months. My levels are back to normal ranges since being prescribed thyroid hormone replacement therapy.
Remember: Hypo is ‘underactive’, Hyper is ‘overactive’. Sometimes there are very few symptoms.
Also worth mentioning something called the ‘Parathyroid’ as these glands can frequently be related to NET Cancer (see my blog on Multiple Endocrine Neoplasia(MEN)). It’s another subject in its own right but I just wanted to emphasise that this is a totally different organ with a totally different function (it regulates Calcium). They are located adjacent to the Thyroid, thus the term ‘para’.
Quick primer on Thyroid Cancer
There are a number of different types of Thyroid Cancer
Papillary thyroid cancer is the most common type of thyroid cancer, accounting for about 80% of thyroid cancers. While papillary thyroid cancer typically occurs in only one lobe of the thyroid gland, it may arise in both lobes in up to 10% to 20% of cases. Papillary thyroid cancer is most common in women of childbearing age. It sometimes is caused by exposure to radiation. Even though papillary thyroid cancer is usually not an aggressive type of cancer, it often metastasizes (spreads) to the lymph nodes in the neck. Papillary thyroid cancer treatment usually is successful.
Follicular thyroid cancer accounts for about 10% of thyroid cancers. Like papillary thyroid cancer, follicular thyroid cancer usually grows slowly. Its outlook is similar to papillary cancer, and its treatment is the same. Follicular thyroid cancer usually stays in the thyroid gland but sometimes spreads to other parts of the body, such as the lungs or bone. However, it usually does not spread to lymph nodes. It is more common in countries where diets do not contain enough iodine.
There is a type of thyroid tumour which has recently been removed as a type of cancer. “Encapsulated follicular variant of papillary thyroid carcinoma” is now known as “noninvasive follicular thyroid neoplasm with papillary thyroid-like nuclear features” or NIFTP. The word ‘carcinoma’ has gone. Read about this here.
Hurthle cell carcinoma, also called oxyphil cell carcinoma, is a type of follicular thyroid cancer. Most patients diagnosed with Hurthle cell cancer do well, but the outlook may change based on the extent of disease at the time of diagnosis.
Medullary thyroid cancer (MTC) is the only type of thyroid cancer that develops in the parafollicular cells of the thyroid gland. It accounts for 3% to 10% of thyroid cancers. Medullary cancer cells usually make and release into the blood proteins called calcitonin and/or carcinoembryonic antigen, which can be measured and used to follow the response to treatment for the disease. Sometimes medullary cancer spreads to the lymph nodes, lungs or liver before a nodule is found or the patient has symptoms. MTC can be treated more successfully if it is diagnosed before it has spread. There are two types of MTC:
Sporadic MTC is more common, accounting for 85% of medullary thyroid cancers. It is found mostly in older adults and is not inherited.
Familial MTC is inherited, and it often develops in childhood or early adulthood. If familial MTC occurs with tumours of certain other endocrine organs (parathyroid and adrenal glands), it is called multiple endocrine neoplasia type 2 (see my blog on MEN 2).
Anaplastic thyroid cancer is the most dangerous form of thyroid cancer. It is makes up only 1% of thyroid cancers. It is believed that anaplastic thyroid cancer grows from a papillary or follicular tumour that mutates further to this aggressive form. Anaplastic thyroid cancer spreads rapidly into areas such as the trachea, often causing breathing difficulties. Anaplastic thyroid cancer sometimes is called undifferentiated thyroid cancer because the cells are so different from normal thyroid tissue.
Thyroid cancer is not very common but diagnoses are ‘skyrocketing’ most likely due to advanced detection techniques. Most are very slow-growing with 5 year survival of 97% according to MD Anderson. There is a very interesting article about the overdiagnosis of Thyroid cancer which I found useful given my situation. You can read it here.
Thyroid ‘nodules’ would appear to be very common with 50-70% of all 50-70 year olds having at least one nodule present and statistically, 95% of these are benign (see EndocrineWeb)
In a previous life, I used the term ‘smoke and mirrors’ quite a bit. I was used to dealing with many different types of people, some who wanted something, some who wanted to buy or sell something. Most of the time it was overt but the devil was usually in the detail. Sometimes there was an element of ‘covertness’ or a ‘hidden agenda’. It was always tricky working out the details of the hidden agenda and sometimes it was only known when it was too late. Some of you will already be seeing where I’m going with this line of thinking – if so, you worked out my hidden agenda!
‘Smoke and Mirrors’ is basically a term connected to the art of deception, a con trick, a way in through confusion and trickery (think magicians on TV!).
Whilst certain cancers can appear with precise symptoms and leave you under no illusion what you’re facing, others can be a bit more circumspect – Neuroendocrine Cancer can be one of those. It will fool you into thinking you’re not even ill and even when it puts its head above the parapet, this can come over as a routine illness and/or vague symptoms which will deceive both you and your physicians. Thus why awareness is really important. I won’t repeat my key messages but you can find them here in my blog entitled “Neuroendocrine Cancer can be silent – but it doesn’t mean we should be”– the more these posts and ones like it are shared, the quicker we can discover the hidden agenda.
I have another hidden agenda! I was inspired to write this post by my friend and blogger Shannon – she writes a blog called ‘A tale of two tumours’. I really like this blog because there are no hidden agendas, what you see is what you get and she has catchy titles. I also like Shannon because she has a great attitude despite the fact that she is probably still looking for the ‘hidden agenda’ or at least bits of it (then again perhaps we all are?).
Shannon has one of the uncommon variants of our disease, one of those tricky cases it would seem. Her issues started some time ago and she was eventually diagnosed with Cushing’s Disease (see my Syndrome blog). She has previous issues with pituitary, parathyroid and recently diagnosed with a Thymic NET. She believes there is a potential connection with MEN1 (see my blog Running in the Family) but this is currently dismissed by her physicians.
There is potentially a new problem outlined in her latest blog which inspired me to write this post. She has a very strange symptom in that she can smell smoke despite there not being any smoke and this happens in different locations. Her latest blog is her story about this symptom and what happened next. Excuse the language but I would be frustrated too! Read the blog ‘Where there is smoke …..’ by ‘clicking here’.
I wish Shannon well and hope she gets some answers – no more tumours please. You are a survivor!
Thanks for listening
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We all know that Neuroendocrine Tumours (NETs) and their syndromes are complex but there is even more complexity to be found in a group of related disorders known as Multiple Endocrine Neoplasia (MEN). I recommend all NET patients should try to understand the basics of MEN and vice versa, particularly as both conditions seem to come with a plethora of endocrine related effects.
MEN patients will normally have a tumour in at least two endocrine glands – thus the terms ‘Multiple’ and ‘Endocrine’ (tumours can also develop in other organs and tissues). Neoplasia is just another name for tumour and these can be non-cancerous (benign) or cancerous (malignant) with the potential to metastasize.
MEN syndromes can comprise varying combinations of tumours and many will be aware of the tumour risks from family knowledge. So putting the heredity aspects to one side, it’s potentially an extremely challenging surveillance and subsequent diagnostic scenario if (and when) these risks are realised. To add to the complexity, some of the associated tumours can be sporadic (non hereditary) classic Neuroendocrine Tumours in various locations.
MEN is actually an umbrella term for a number of types (syndromes) of the disease – MEN1, MEN2a and 2b (2b was formerly MEN3). There’s a new kid on the block called MEN4 which is extremely rare.
In the most basic of terms regarding the relationship with tumours:
MEN1 seems to be centred on tumours of the parathyroid glands, the pituitary gland, and the pancreas (the 3 P’s).
MEN2a mainly focuses on medullary thyroid carcinoma, pheochromocytoma, parathyroid hyperplasia or adenomas (causing hyperparathyroidism), and occasionally cutaneous lichen amyloidosis.
MEN2b medullary thyroid carcinoma, pheochromocytoma, multiple mucosal neuromas and intestinal ganglioneuromas, and often a marfanoid habitus and other skeletal abnormalities.
MEN4 – A relatively new MEN variant and related to the CDKN1B gene, similar to MEN1 but normally only 2 of the 3 Ps, parathyroid and pituitary. Also referred to as MENX Possible association with tumors of the adrenals, kidneys, and reproductive organs.
What is particularly distinctive with MEN is that they are inherited disorders (familial). That means that they can be passed down in families, with each child of an affected parent having a 1 in 2 or 50% risk of inheritance. Consequently genetic screening/testing is normally undertaken in established MEN families and those at risk of MEN.
You may also have heard of other rare NETs with a familial aspect, in particular Pheochromocytomas (adrenal gland tumours) and Paragangliomas (outside the adrenal gland), Not all are inherited and I mention them because of the connection with MEN2a and 2b.
I’m grateful to my friend and MEN patient Linda Hageman for supporting my blog activities and also for allowing me to join the AMEN support group to learn more. This is one of the friendliest and well run support groups I’ve seen. On this site, you will find Dr Mark Lewis, an Oncologist and MEN patient who supports Linda (who is a Nurse) with a ‘Ask the Doctor’ section on their website.
Until I was diagnosed with metastatic Neuroendocrine Cancer, I didn’t have a clue about hormones – it’s one of those things you just take for granted. However, hormones are vital to human health (male and female) and it’s only when things go wrong you suddenly appreciate how important they are ……..like a lot of other things in life I suppose! The presence of over-secreting hormones (often called peptides throughout) is useful to aid diagnosis albeit it often means the tumours have metastasized. It’s also a frequent indication that the person has an associated NET syndrome.
This is a really complex area and to understand the hormone problems associated with Neuroendocrine Cancer, you need to have a basic knowledge of the endocrine and neuroendocrine systems. I’ve no intention of explaining that (!) – other than the following high level summary:
Glands in the endocrine system use the bloodstream to monitor the body’s internal environment and to communicate with each other through substances called hormones, which are released into the bloodstream. Endocrine glands include; Pituitary, Hypothalmus, Thymus, Pineal, Testes, Ovaries Thyroid, Adrenal, Parathyroid, Pancreas.
A Hormone is a chemical that is made by specialist cells, usually within an endocrine gland, and it is released into the bloodstream to send a message to another part of the body. It is often referred to as a ‘chemical messenger’. In the human body, hormones are used for two types of communication. The first is for communication between two endocrine glands, where one gland releases a hormone which stimulates another target gland to change the levels of hormones that it is releasing. The second is between an endocrine gland and a target organ, for example when the pancreas releases insulin which causes muscle and fat cells to take up glucose from the bloodstream. Hormones affect many physiological activities including growth, metabolism, appetite, puberty and fertility.
The Endocrine system. The complex interplay between the glands, hormones and other target organs is referred to as the endocrine system.
The Neuroendocrine System. The diffuse neuroendocrine system is made up of neuroendocrine cells scattered throughout the body. These cells receive neuronal input and, as a consequence of this input, release hormones to the blood. In this way they bring about an integration between the nervous system and the endocrine system (i.e. Neuroendocrine). A complex area but one example of what this means is the adrenal gland releasing adrenaline to the blood when the body prepares for the ‘fight or flight’ response in times of stress, ie, for vigorous and/or sudden action.
Hormones – the NET Effect
At least one or more hormones will be involved at various sites and even within certain syndromes, the dominant and offending hormone may differ between anatomical tumour sites. For example, NETs of the small intestine may overproduce serotonin and other hormones which can cause a characteristic collection of symptoms currently called carcinoid syndrome. The key symptoms are flushing,diarrhea and general abdominal pain, loss of appetite, fast heart rate and shortness of breath and wheezing. The main symptom for me was facial flushing and this was instrumental in my eventual diagnosis. The fact that I was syndromic at the point of diagnosis made it easier to discover, albeit the trigger for the investigation was a fairly innocuous event. Other types of NETs are also affected by the overproduction of hormones including Insulinomas, Gastrinomas, Glucagonomas, VIPomas, Somatostatinomas, and others. These can cause their own syndromes and are not part of carcinoid syndrome as some organisations incorrectly state. For more on NET syndromes – Read Here.
So are hormones horrible?
Absolutely not, they are essential to the normal function of the human body. For example if you didn’t have any of the hormone Serotonin in your system, you would become extremely ill. On the other hand, if your glands start secreting too much of certain hormones, your body could become dysfunctional and in some scenarios, this situation could become life threatening. So hormones are good as long as the balance is correct. NET patients with an oversecreting tumor may be classed as “functional”.
Functional tumors make extra amounts of hormones, such as gastrin, insulin, and glucagon, that cause signs and symptoms.
Nonfunctional tumors do not make extra amounts of hormones. Signs and symptoms are caused by the tumor as it spreads and grows. Many NET patients are deemed to be “non-functioning” with normal hormone levels. It’s also accurate to say that many can move from one stage to the other.
Location Location Location
It’s accurate to say that the type and amount of hormone secretion differs between locations or sites of the functional tumor and this can also create different effects. The division of NETs into larger anatomical regions appears to differ depending on where you look but they all look something likes this:
Foregut NETs: In the respiratory tract, thymus, stomach, duodenum, and pancreas. This group mostly lack the enzyme aromatic amino decarboxylase that converts 5-HTP (5-Hydroxytryptophan – a precursor to serotonin) to serotonin (5-HT); such tumours tend to produce 5-HTP and histamine instead of serotonin.
The Pancreas is a particularly prominent endocrine organ and can produce a number of different syndromes each with their associated hormone oversecretion – although many can be non-functional (at least to begin with), (see below for more detail). It’s also possible to see predominantly serotonin secreting tumors in places such as the pancreas (although what you would call that type of NET is open for debate).
Lung NETs rarely produce serotonin, but may instead secrete histamine causing an ‘atypical’ carcinoid syndrome with generalized flushing, diarrhea, periorbital oedema, lacrimation and asthma. They may also produce adrenocorticotropic hormone (ATCH) or corticotropin-releasing factor (CRP), resulting in an ectopic Cushing’s syndrome. Please note the respiratory tract and thymus are not really anatomically pure ‘Foregut’ – but in NETs, grouped there for convenience.
Gastric (Stomach) NETs. Gastrin is the main hormone but there can also be histamine producing an atypical carcinoid syndrome effect.
Midgut NETs: In the small intestine, appendix, and ascending colon. For example, serotonin secreting tumors tend to be associated with carcinoid syndrome which tends to be associated with midgut NETs and this is normally the case. Many texts will also tell you that a syndrome only occurs at a metastatic stage. Both are a good rule of thumb but both are technically incorrect. For example, ovarian NETs can have a form of carcinoid syndrome without liver metastasis (tends to be described as atypical carcinoid syndrome).
Hindgut NETs (transverse, descending colon and rectum) cannot convert tryptophan to serotonin and other metabolites and therefore rarely cause carcinoid syndrome even if they metastasise to the liver.
Less Common Locations – there are quite a few less common NET locations which may involve less common hormones – some are covered below including the key glands contributing to NETs.
Unknown Primary? – One clue to finding the primary might be by isolating an offending hormone causing symptoms.
The key NET hormones
I used the example of Serotoninabove because it is the most cited problem with NET Cancer although it does tend to be most prevalent in midgut tumors. Serotonin is a monoamine neurotransmitter synthesized from Tryptophan, one of the eight essential amino acids (defined as those that cannot be made in the body and therefore must be obtained from food or supplements). About 90% of serotonin produced in the body is found in the enterochromaffin cells of the gastrointestinal (GI) tract where it is used mainly to regulate intestinal movements amongst other functions. The remainder is synthesized in the central nervous system where it mainly regulates mood, appetite, and sleep. Please note there is no transfer of serotonin across the blood-brain barrier.
Alterations in tryptophan metabolism may account for many symptoms that accompany carcinoid syndrome. Serotonin in particular is the most likely cause of many features of carcinoid syndrome as it stimulates intestinal motility and secretion and inhibits intestinal absorption. Serotonin may also stimulate fibroblast growth and fibrogenesis and may thus account for peritoneal and valvular fibrosis encountered in such tumours; serotonin, however, it is said not to be associated with flushing. The diversion of tryptophan to serotonin may lead to tryptophan deficiency as it becomes unavailable for nicotinic acid synthesis, and is associated with reduced protein synthesis and hypoalbuminaemia; this may lead to the development of pellagra (skin rash, glossitis, stomatitis, confusion/dementia).
Serotonin is also thought to be responsible for ‘right sided’ heart disease (Carcinoid Heart Disease). It is thought that high levels of serotonin in the blood stream damages the heart, leading to lesions which cause fibrosis, particularly of the heart valves. This generally affects the right side of the heart when liver metastases are present. The left side of the heart is usually not affected because the lungs can break down serotonin. Right sided heart failure symptoms include swelling (edema) in the extremities and enlargement of the heart.
Whilst serotonin can be measured directly in the blood, it’s said to be more accurate to measure 5HIAA (the output of serotonin) via blood or urine, the latter is said to be the most accurate.
Tackykinins include Substance P, Neurokinin A, Neuropeptide K and others. They are active in the enterochromaffin cells of the GI tract but can also be found in lung, appendiceal and ovarian NETs, and also in Medullary Thyroid Carcinoma and Pheochromocytomas. They are thought to be involved in flushing and diarrhea in midgut NETs. The most common tachykinin is Substance P, which is a potent vasodilator (substances which open up blood vessels). Telangiectasias are collections of tiny blood vessels which can develop superficially on the faces of people who have had NETs for several years. They are most commonly found on the nose or upper lip and are purplish in color. They are thought to be due to chronic vasodilatation.
Histamine is a hormone that is chemically similar to the hormones serotonin, epinephrine, and norepinephrine. After being made, the hormone is stored in a number of cells (e.g., mast cells, basophils, enterochromaffin cells). Normally, there is a low level of histamine circulating in the body. However (and as we all know!), the release of histamine can be triggered by an event such as an insect bite. Histamine causes the inconvenient redness, swelling and itching associated with the bite. For those with severe allergies, the sudden and more generalized release of histamine can be fatal (e.g., anaphylactic shock). Mast cell histamine has an important role in the reaction of the immune system to the presence of a compound to which the body has developed an allergy. When released from mast cells in a reaction to a material to which the immune system is allergic, the hormone causes blood vessels to increase in diameter (e.g., vasodilation) and to become more permeable to the passage of fluid across the vessel wall. These effects are apparent as a runny nose, sneezing, and watery eyes. Other symptoms can include itching, burning and swelling in the skin, headaches, plugged sinuses, stomach cramps, and diarrhea. Histamine can also be released into the lungs, where it causes the air passages to become constricted rather than dilated. This response occurs in an attempt to keep the offending allergenic particles from being inhaled. Unfortunately, this also makes breathing difficult. An example of such an effect of histamine occurs in asthma. Histamine has also been shown to function as a neurotransmitter (a chemical that facilitates the transmission of impulses from one neural cell to an adjacent neural cell).
In cases of an extreme allergic reaction, adrenaline is administered to eliminate histamine from the body. For minor allergic reactions, symptoms can sometimes be lessened by the use of antihistamines that block the binding of histamine to a receptor molecule. Histamine is thought to be involved with certain types and locations of NET, including Lung and foregut NETs where they can cause pulmonary obstruction, atypical flush and hormone syndromes.
Histamine, another amine produced by certain NETs (particularly foregut), may be associated with an atypical flushing and pruritus; increased histamine production may account for the increased frequency of duodenal ulcers observed in these tumours.
Kallikrein is a potent vasodilator and may account for the flushing and increased intestinal mobility.
Although prostaglandins are overproduced in midgut tumours, their role in the development of the symptoms of carcinoid syndrome is not well established but triggering peristalsis is mentioned in some texts.
Bradykinin acts as a blood vessel dilator. Dilation of blood vessels can lead to a rapid heartbeat (tachycardia) and a drop in blood pressure (hypotension). Dilation of blood vessels may also be partly responsible for the flushing associated with carcinoid syndrome.
Gastrin is a hormone that is produced by ‘G’ cells in the lining of the stomach and upper small intestine. During a meal, gastrin stimulates the stomach to release gastric acid. This allows the stomach to break down proteins swallowed as food and absorb certain vitamins. It also acts as a disinfectant and kills most of the bacteria that enter the stomach with food, minimising the risk of infection within the gut. Gastrin also stimulates growth of the stomach lining and increases the muscle contractions of the gut to aid digestion. Excess gastrin could indicate a NET known as a Gastric NET (stomach) or a pNET known as Gastrinoma (see pancreatic hormones below).
Calcitonin is a hormone that is produced in humans by the parafollicular cells (commonly known as C-cells) of the thyroid gland. Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone. This means that it acts to reduce calcium levels in the blood. This hormone tends to involve Medullary Thyroid Carcinoma and Hyperparathyroidism in connection to those with Multiple Endocrine Neoplasia. Worth also pointing out the existence of Calcitonin Gene-Related Peptide (CGRP) which is a member of the calcitonin family of peptides and a potent vasodilator. Please note that hypothyroidism is often a side effect of NETs or treatment for NETs – please click here to read about the connection.
HPA AXIS – It’s important to note something called the HPA axis when discussing pituitary hormones as there is a natural and important connection and rhythm between the Hypothalamus, Pituitary and the Adrenal glands. However, I’m only covering the pituitary and adrenal due to their strong connection with NETs.
Adrenocorticotropic hormone (ATCH) is made in the corticotroph cells of the anterior pituitary gland. It’s production is stimulated by receiving corticotrophin releasing hormone (CRH) from the Hypothalamus. ATCH is secreted in several intermittent pulses during the day into the bloodstream and transported around the body. Like cortisol (see below), levels of ATCH are generally high in the morning when we wake up and fall throughout the day. This is called a diurnal rhythm. Once ACTH reaches the adrenal glands, it binds on to receptors causing the adrenal glands to secrete more cortisol, resulting in higher levels of cortisol in the blood. It also increases production of the chemical compounds that trigger an increase in other hormones such as adrenaline and noradrenaline. If too much is released, The effects of too much ATCH are mainly due to the increase in cortisol levels which result. Higher than normal levels of ATCH may be due to:
Cushing’s disease – this is the most common cause of increased ATCH. It is caused by a tumor in the pituitary gland (PitNET), which produces excess amounts of ATCH. (Please note, Cushing’s disease is just one of the numerous causes of Cushing’s syndrome). It is likely that a Cortisol test will also be ordered if Cushing’s is suspected.
A tumour outside the pituitary gland, producing ATCH is known as an ectopic ATCH. With NETs, this is normally a pNET, Lung/Bronchial/Pulmonary NET or Pheochromocytoma.
Adrenaline and Noradrenline
These are two separate but related hormones and neurotransmitters, known as the ‘Catecholamines’. They are produced in the medulla of the adrenal glands and in some neurons of the central nervous system. They are released into the bloodstream and serve as chemical mediators, and also convey the nerve impulses to various organs. Adrenaline has many different actions depending on the type of cells it is acting upon. However, the overall effect of adrenaline is to prepare the body for the ‘fight or flight’ response in times of stress, i.e. for vigorous and/or sudden action. Key actions of adrenaline include increasing the heart rate, increasing blood pressure, expanding the air passages of the lungs, enlarging the pupil in the eye, redistributing blood to the muscles and altering the body’s metabolism, so as to maximise blood glucose levels (primarily for the brain). A closely related hormone, noradrenaline, is released mainly from the nerve endings of the sympathetic nervous system (as well as in relatively small amounts from the adrenal medulla). There is a continuous low-level of activity of the sympathetic nervous system resulting in release of noradrenaline into the circulation, but adrenaline release is only increased at times of acute stress. These hormones are normally related to adrenal and extra adrenal NETs such as Pheochromocytoma and Paraganglioma. Like serotonin secreting tumours, adrenal secreting tumours convert the offending hormone into something which comes out in urine. In fact, this is measured (amongst other tests) by 24 hour urine test very similar to 5HIAA (with its own diet and drug restrictions). It’s known as 24-hour urinary catacholamines and metanephrines. Worth noting that adrenaline is also known as Epinephrine (one of the 5 E’s of Carcinoid Syndrome).
This is a steroid hormone, one of the glucocorticoids, made in the cortex of the adrenal glands and then released into the blood, which transports it all round the body. Almost every cell contains receptors for cortisol and so cortisol can have lots of different actions depending on which sort of cells it is acting upon. These effects include controlling the body’s blood sugar levels and thus regulating metabolism acting as an anti-inflammatory, influencing memory formation, controlling salt and water balance, influencing blood pressure. Blood levels of cortisol vary dramatically, but generally are high in the morning when we wake up, and then fall throughout the day. This is called a diurnal rhythm. In people who work at night, this pattern is reversed, so the timing of cortisol release is clearly linked to daily activity patterns. In addition, in response to stress, extra cortisol is released to help the body to respond appropriately. Too much cortisol over a prolonged period of time can lead to Cushing’s syndrome. Cortisol oversecretion can be associated with Adrenal Cortical Carcinoma (ACC) which can sometimes be grouped within the NET family.
Other hormones related to ACC include:
Androgens (e.g. Testosterone) – increased facial and body hair, particularly females. Deepened voice in females.
Estrogen – early signs of puberty in children, enlarged breast tissue in males.
Aldosterone – weight gain, high blood pressure.
Adrenal Insufficiency (Addison’s Disease) occurs when the adrenal glands do not produce enough of the hormone cortisol and in some cases, the hormone aldosterone. For this reason, the disease is sometimes called chronic adrenal insufficiency, or hypocortisolism.
Parathyroid hormone (PTH) is secreted from four parathyroid glands, which are small glands in the neck, located behind the thyroid gland. Parathyroid hormone regulates calcium levels in the blood, largely by increasing the levels when they are too low. A primary problem in the parathyroid glands, producing too much parathyroid hormone causes raised calcium levels in the blood (hypercalcaemia – primary hyperparathyroidism). You may also be offered an additional test called Parathyroid Hormone-Related Peptide (PTHrP). They would probably also measure Serum Calcium in combination with these type of tests. The parathyroid is one of the ‘3 p’ locations often connected to Multiple Endocrine Neoplasia – MEN 1
Pancreatic Hormones (Syndromes)
Pancreatic neuroendocrine tumors form in hormone-making cells of the pancreas. You may see these described as ‘Islet Cells’ or ‘Islets of Langerhans’ after the scientist who discovered them. Pancreatic NETs may also be functional or non-functional:
Functional tumors make extra amounts of hormones, such as gastrin, insulin, and glucagon, that cause signs and symptoms.
Nonfunctional tumors do not make extra amounts of hormones. Signs and symptoms are caused by the tumor as it spreads and grows.
There are different kinds of functional pancreatic NETs. Pancreatic NETs make different kinds of hormones such as gastrin, insulin, and glucagon. Functional pancreatic NETs include the following:
Gastrinoma: A tumor that forms in cells that make gastrin. Gastrin is a hormone that causes the stomach to release an acid that helps digest food. Both gastrin and stomach acid are increased by gastrinomas. When increased stomach acid, stomach ulcers, and diarrhea are caused by a tumor that makes gastrin, it is called Zollinger-Ellison syndrome. A gastrinoma usually forms in the head of the pancreas and sometimes forms in the small intestine. Most gastrinomas are malignant (cancer).
Insulinoma: A tumor that forms in cells that make insulin. Insulin is a hormone that controls the amount of glucose (sugar) in the blood. It moves glucose into the cells, where it can be used by the body for energy. Insulinomas are usually slow-growing tumors that rarely spread. An insulinoma forms in the head, body, or tail of the pancreas. Insulinomas are usually benign (not cancer).
Glucagonoma: A tumor that forms in cells that make glucagon. Glucagon is a hormone that increases the amount of glucose in the blood. It causes the liver to break down glycogen. Too much glucagon causes hyperglycemia (high blood sugar). A glucagonoma usually forms in the tail of the pancreas. Most glucagonomas are malignant (cancer).
Pancreatic Polypeptide (PPoma). A pancreatic polypeptide is a polypeptide hormone secreted by the pancreatic polypeptide (PP) cells of the islets of Langerhans in the endocrine portion of the pancreas. Its release is triggered in humans by protein-rich meals, fasting, exercise, and acute hypoglycemia and is inhibited by somatostatin and intravenous glucose. The exact biological role of pancreatic polypeptide remains uncertain. Excess PP could indicate a pNET known as PPoma.
Other types of tumors: There are other rare types of functional pancreatic NETs that make hormones, including hormones that control the balance of sugar, salt, and water in the body. These tumors include:
VIPomas, which make vasoactive intestinal peptide. VIPoma may also be called Verner-Morrison syndrome, pancreatic cholera syndrome, or the WDHA syndrome (Watery Diarrhea, Hypokalemia (low potassium)and Achlorhydria).
Somatostatinomas, which make somatostatin. Somatostatin is a hormone produced by many tissues in the body, principally in the nervous and digestive systems. It regulates a wide variety of physiological functions and inhibits the secretion of other hormones, the activity of the gastrointestinal tract and the rapid reproduction of normal and tumour cells. Somatostatin may also act as a neurotransmitter in the nervous system.
Having certain syndromes can increase the risk of pancreatic NETs.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Multiple endocrine neoplasia type 1 (MEN1) syndrome is a risk factor for pancreatic NETs.
Signs and symptoms of pancreatic NETs
Signs or symptoms can be caused by the growth of the tumor and/or by hormones the tumor makes or by other conditions. Some tumors may not cause signs or symptoms. Check with your doctor if you have any of these problems.
Signs and symptoms of a non-functional pancreatic NET
A non-functional pancreatic NET may grow for a long time without causing signs or symptoms. It may grow large or spread to other parts of the body before it causes signs or symptoms, such as:
A lump in the abdomen.
Pain in the abdomen or back.
Yellowing of the skin and whites of the eyes.
Signs and symptoms of a functional pancreatic NET
The signs and symptoms of a functional pancreatic NET depend on the type of hormone being made.
Too much gastrin may cause:
Stomach ulcers that keep coming back.
Pain in the abdomen, which may spread to the back. The pain may come and go and it may go away after taking an antacid.
The flow of stomach contents back into the esophagus (gastroesophageal reflux).
Too much insulin may cause:
Low blood sugar. This can cause blurred vision, headache, and feeling lightheaded, tired, weak, shaky, nervous, irritable, sweaty, confused, or hungry.
Too much glucagon may cause:
Skin rash on the face, stomach, or legs.
High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
Blood clots. Blood clots in the lung can cause shortness of breath, cough, or pain in the chest. Blood clots in the arm or leg can cause pain, swelling, warmth, or redness of the arm or leg.
Weight loss for no known reason.
Sore tongue or sores at the corners of the mouth.
Too much vasoactive intestinal peptide (VIP) may cause:
Very large amounts of watery diarrhea.
Dehydration. This can cause feeling thirsty, making less urine, dry skin and mouth, headaches, dizziness, or feeling tired.
Low potassium level in the blood. This can cause muscle weakness, aching, or cramps, numbness and tingling, frequent urination, fast heartbeat, and feeling confused or thirsty.
Cramps or pain in the abdomen.
Weight loss for no known reason.
Too much somatostatin may cause:
High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
Steatorrhea (very foul-smelling stool that floats).
Yellowing of the skin and whites of the eyes.
Weight loss for no known reason.
Too much pancreatic polypeptide may cause:
an enlarged liver.
Clearly the presenting symptoms will give doctors a clue to the oversecreting hormone (see list above). Excessive secretions or high levels of hormones and other substances can be measured in a number of ways. For example:
Well known tests for the most common types of NET include 5-Hydroxyindoleacetic Acid (5-HIAA) 24 hour urine test which is also measured by a blood draw. Note: -tumor markers can be measured simultaneously e.g. Chromogranin A (CgA) blood test and/or Pancreastatin as there can very often be a correlation between tumour mass and tumour secreting activity. CgA / Pancreastatin is a blood test which measures a protein found in many NET tumour cells. These marker tests are normally associated with tumour mass rather than tumour functionality.
By measuring the level of 5-HIAA in the urine or blood, healthcare providers can calculate the amount of serotonin in the body (5-HIAA is a by-product of serotonin). 5-HIAA test is the most common biochemical test for carcinoid syndrome or the degree of how ‘functional’ tumours are. If you’ve understood the text above, you can now see why there are dietary and drug restrictions in place prior to the test.
Pancreatic Hormone testing. There are other tests for other hormones and there is a common test which measured the main hormones seen in NETs. It may be called different things in different countries, but in UK, it’s known as a ‘Fasting Gut Hormone Profile‘.
Scratching the surface here so for a comprehensive list of marker tests for NETs, have aread here.
Treatment for Over-secreting Hormones
Of course, reducing tumour bulk through surgery and other treatment modalities, should technically reduce over-secretion (I suspect that doesn’t work for all). Other treatments may have the dual effect of reducing tumour burden and the effects of hormone oversecretions.
One of the key treatment breakthroughs for many NET cancer patients, is the use of ‘Somatostatin Analogues’ mainly branded as Octreotide (Sandostatin) or Lanreotide (Somatuline). People tend to associate these drugs with serotonin related secretions and tumours but they are in actual fact useful for many others including the pancreatic NETs listed above. Patients will normally be prescribed these drugs if they are displaying these symptoms but some people may be more avid to the drug than others and this may influence future use and dosages. This is another complex area but I’ll try to describe the importance here in basic terms. Somatostatin is a naturally occurring protein in the human body. It is an inhibitor of various hormones secreted from the endocrine system (some of which were listed above) and it binds with high affinity to the five somatostatin receptors found on secretory endocrine cells. NETs have membranes covered with receptors for somatostatin. However, the naturally occurring Somatostatin has limited clinical use due to its short half-life (<3 min). Therefore, specific somatostatin analogues (synthetic versions) have been developed that bind to tumours and block hormone release. Thus why Octreotide and Lanreotide do a good job of slowing down hormone production, including many of the gut hormones controlling emptying of the stomach and bowel. It also slows down the release of hormones made by the pancreas, including insulin and digestive enzymes – so there can be side effects including fat malabsorption.
The recent introduction of Telotristat Ethyl(XERMELO) is interesting as that inhibits a precursor to serotonin and reduces diarrhea in those patients where it is not adequately controlled by somatostatin analogues.
Other than the effects of curative or cytoreductive surgery, some NETs may have very specialist drugs for inhibiting the less common hormone types. This is not an exhaustive list.
Worth also noting that oversecreting hormones can contribute to a phenomenon known as Carcinoid Crisis – read more here. For catacholamine secreting tumors (Pheochromocytoma/Paraganglioma), this may be known as Intraoperative Hypertensive Crisis
Sorry about the long article – it’s complex and you should always consult your specialist about issues involving hormones, testing for hormones and treating any low or high scores.