Since I started blogging, I’ve had to become quite savvy at forming headlines for my posts as the wording can be a factor in whether someone reads it or not. A post picture can also influence. There’s a third factor and that is credibility – I’d like to think I’ve worked hard to earn that level of trust in my ‘product’. I use the NET to talk about NETs! I’m a genuine guy with a genuine purpose and I don’t want to sell you anything – my ‘product’ is free.
However, the ‘NET’ can also provide ‘misinformation’. Unfortunately ‘misinformation’ also includes ‘alleged’ cures for various ailments including cancer. I think we’ve all been there, we check twitter, Facebook, Pinterest etc and we find the ubiquitous miracle cures for every illness under the sun, annoying shared by our friends. Easy to find, easy to read and worryingly, easy to share. Surely these cures must be true, after all…..it’s on the ‘NET’.
I was, therefore, delighted to see that the U.S. Food and Drug Administration (FDA) recently posted warning letters addressed to 14 U.S.-based companies illegally selling more than 65 products that fraudulently claim to prevent, diagnose, treat or cure cancer. The products are marketed and sold without FDA approval, most commonly on websites and social media platforms. Clearly, this is not just a USA problem, I suspect you all could tell me similar stories from your own countries? I just read a story from my own local area only last week. This is only the tip of the iceberg though!
Most of these claims are from obscure unheard of websites (clue 1) and yet they claim to have the cure for all sorts of illness including cancer (clue 2). They normally have a product to sell (clue 3). Clue 4 and onwards can be found by digging into their claims to see if there is any scientific evidence – normally there’s none; or it looks believable but the authors are also the owners of the company selling the product.
Here are some of the tactics they use plus a commentary from the US FDA:
One product does it all. Be suspicious of products that claim to cure a wide range of diseases. A New York firm claimed its products marketed as dietary supplements could treat or cure senile dementia, brain atrophy, atherosclerosis, kidney dysfunction, gangrene, depression, osteoarthritis, dysuria, and lung, cervical and prostate cancer. In October 2012, at FDA’s request, U.S. marshals seized these products.
Personal testimonials. Success stories, such as, “It cured my diabetes” or “My tumors are gone,” are easy to make up and are not a substitute for scientific evidence.
Quick fixes. Few diseases or conditions can be treated quickly, even with legitimate products. Beware of language such as, “Lose 30 pounds in 30 days” or “eliminates skin cancer in days.”
“All natural.” Some plants found in nature (such as poisonous mushrooms) can kill when consumed. Moreover, FDA has found numerous products promoted as “all natural” but that contain hidden and dangerously high doses of prescription drug ingredients or even untested active artificial ingredients.
“Miracle cure.” Alarms should go off when you see this claim or others like it such as, “new discovery,” “scientific breakthrough” or “secret ingredient.” If a real cure for a serious disease were discovered, it would be widely reported through the media and prescribed by health professionals—not buried in print ads, TV infomercials or on Internet sites.
Conspiracy theories. Claims like “The pharmaceutical industry and the government are working together to hide information about a miracle cure” are always untrue and unfounded. These statements are used to distract consumers from the obvious, common-sense questions about the so-called miracle cure.
The rise of the internet means that we need to be very careful what we believe, particularly when the term ‘fake news’ is abundant. The people who work in this ‘dark’ industry are very clever, playing on the mind and fears of those who suffer from cancer and other illnesses which they claim they can cure. Many of them are easy to spot or at least attract your suspicion as you can see above. I’m concerned that some of them make their way onto patient forums unchallenged by the administrators (leave those groups, they are a danger to your health). Here’s something you’re probably not aware of….. I am targeted weekly by people and organisations who want me to advertise their ‘product’ to you guys, some of them are very dubious indeed. I have a “no selling” rule on my site so it’s easy for me to reject anyone approaching me in this way – the very dubious are blocked immediately.
See an article where this post was featured …… Click Here
I will never share this sort of thing on my site and I even check official looking mainstream media articles for the background scientific data before I would share here. For me, regardless of the headline or post picture, this is where credibility comes in. Often (whilst everyone else is sharing), I wait on informed comment from credible organisations such as Cancer Research UK who very frequently have to dampen down the excitement caused by mainstream media ‘headlines’ by providing a more balanced and evidence based view. I’ve blogged before about Cancer Research UK in the post The trouble with the NET (Part 1), The trouble with the NET (Part 2) (with mention of Steve Jobs and Neuroendocrine Cancer). I particularly like their blog 10 persistent cancer myths debunked.
Sharon said …… “This is SO important. As an RN and a NET patient, I am appalled by some of the things I see on Facebook. People facing chronic or terminal illnesses are so vulnerable. Thank you, Ronny Allan”
One of the most discussed and sometimes confusing subjects on forums is the staging and grading of Neuroendocrine Neoplasms (NENs). Mixing them up is a common error and so it’s important to understand the difference despite the apparent complexity. If I was to make a list of questions for my specialist/Oncologist at diagnosis, it would include “What is the stage, grade and differentiation of my cancer”. To enable me to synchronise with the documented guidance, I’m going to use the following WHO 2017 approved terms in this post:
Neuroendocrine Neoplasm (NEN) – all types of Neuroendocrine tumour of whatever grade (please note Neoplasm is another word for tumour)
Neuroendocrine Tumour (NET) – all well-differentiated tumours (an explanation of differentiation will be provided below)
Neuroendocrine Carcinoma (NEC) – all poorly differentiated tumours
Stage vs Grade
In the most basic of terms, stage is the spread or extent of cancer and grade is the aggressiveness of cancer. They are totally different things and an understanding of both is important as they are critical to predict outcome (to a certain extent) and guide therapy. There is no correlation between the two, you can have the lowest grade with the highest stage (actually very common with NETs).
As patients, we deal with many medical specialists during diagnosis and subsequent treatment. However, we rarely meet the pathologist who plays a critical role in the outcome. Precise diagnosis is what drives patient decisions and treatment. If the pathology is wrong, everything that follows could be incorrect as well. It’s a very important area.
Grading and Ki67
Antigen KI-67 is a nuclear protein that is associated with and may be necessary for cellular proliferation. Ki-67 is therefore an excellent marker to determine the growth fraction of a given cell population. The fraction of Ki-67-positive tumour cells (the Ki-67 labeling index) is often correlated with the clinical course of cancer.
Pathologists normally need to count about a thousand cells in order to determine the percentage of cells that are Ki67 positive – thus why you see Ki67 expressed as a percentage. 0% is the lowest, 100% is the highest. Often, they add greater or less than signs depending on the sample involved, i.e. >5% or <5%. There are other measurement systems in place, mainly Mitotic Count.
The ranges for Neuroendocrine Neoplasms (NENs) are divided in to 3 Grades depending what range the Ki67 number lands in. With NENs, the differentiation (well or poorly) is almost as important at grade 3 (high grade). Grades 1 and 2 are by default well differentiated NETs).
Why is differentiation important?
To fully understand grading, you also need to understand the concept of ‘differentiation’. In the most basic of terms, ‘differentiation’ refers to the extent to which the cancerous cells resemble their non-cancerous counterparts. This is an important point for NETs because many low-grade tumour cells can look very similar to normal cells. The differentiation of a NET has an impact on both prognostics and treatment regimes.
NENs fall into one of three grades based on their differentiation and their proliferative rate. The proliferative rate is measured mainly using two methods known as Miotic Count and Ki-67 index, the latter seems to be more frequently used (but see below for Lung NETs). The Ki-67 index can usually be determined, even in cases of small biopsies but Mitotic rate counting requires a moderate amount of tumour tissue (at least 50 HPFs or 10 mm) and may not be feasible for small biopsies. The Miotic Count method may be preferred or used in addition to Ki-67 for certain Lung NET scenarios as it is said to be more helpful in distinguishing atypical from typical NET (what some might ‘old fashionably’ and incorrectly refer to as Lung Carcinoid tumours), and for small and large cell lung Neuroendocrine Carcinomas (NEC).
Some of you may have heard the term ‘moderately differentiated’ which tended to align with an intermediate grade or Grade 2. However, please note that the term moderately differentiated as a classification was phased out in 2010 by WHO reducing from 3 differentiation levels to 2. Grade 2 is also defined as well differentiated but based on different proliferative rate (see table). High grade was normally referred to as Neuroendocrine Carcinoma indicating it is a faster growing and more aggressive cancer. However, see below for an important change to high grade classification.
Grading – Key WHO 2017 Changes
WHO Classifications of Cancer are published in something known in medical world as “The Blue Book”. For NETs, the 2017 version comprises only the “WHO Classification of Tumours of Endocrine Organs”. Technically this would preclude the digestive system and lung NETs but the leading NET pathologists have submitted a recommendation to normalise all NET Blue Books along the same classification scheme. Worth also noting that the latest ENETS Guidelines are already using the new grading terms. Many sites remain out of date so be careful where you look.
Misc Grading Issues
The proliferative rate can be diverse in NENs, so sampling issues can limit the accuracy of grading. More substantial samples of tumour are therefore preferable for grading thus why the Ki-67 index is preferred for biopsies where large amounts of tissue may not be available. The distinction of low-grade from intermediate grade can be challenging when using small samples. A couple of interesting observations about NET grading which I spotted during my research and ‘forum watching’. You can have multiple primary tumours and these might have different Ki-67 scores. Additionally, on larger tumours, Ki-67 scores can be different on different parts of the tumour. And something I know from my own experience, secondary tumours can have different Ki-67 scores than primary – even a different grade. In my own case, my liver secondary tumours were graded higher than my primary which according to my surgeon is in keeping with a clone of the disease having become more aggressive over time. Royal Free Hospital NET Centre indicates a person’s grade should be taken from the highest biopsy grade taken. This is a fairly complex area but a recent study published by the US National Institute of Health and many anecdotal comments made by NET specialists indicates that is a fairly common scenario.
Summary of Key Changes
The 2017 World Health Organisation (WHO) classification sub-divided Grade 3 into two new entities: a well differentiated high-grade NET and a poorly differentiated high-grade NEC. There may also be a cut-off point in proliferative rate (i.e. Ki-67) between NET and NEC in relation to potential treatment strategies (55% is mentioned for pNETs but I’m currently investigating). Physicians don’t really have much data to support specific guidelines for treatment so all cases will be personalised.
The Grade 1 to 2 Ki-67 cut-off is changed from 2 to < 3 for clarification purposes. There was some discussion as to whether it should be <5 but this was not accepted.
Well differentiated High Grade NETs are now recognised. These are known as a NET rather than a NEC. Both Grade 3 (NET) and Grade 3 (NEC) have the same biopsy marker cut-offs as per the leading slide but it is thought that a threshold reading of 55% could have some influence on the treatment regime. For example, a well differentiated tumour with a Ki67 of less than 55% might benefit from the same treatment given to Grade 1 or 2 patients, whereas a well differentiated tumour with a Ki67 of more than 55% might benefit from the same treatment given to poorly differentiated NEC. Only a guideline and I suspect this is like many things in NENs, very individual, relies on many factors, so your specialist will drive this accordingly. You may see these 2 grades listed as Grade 3a for NET and Grade 3b for NEC.
Previously, Pheochromocytoma did not have an official grading regime, i.e. they were just benign or malignant. Now they are using the same grading system as above. I’m assuming this is the same for Paraganglioma and I will confirm in due course. This is an excellent change and a continuation from the WHO 2010 classification where there was great emphasis away from a benign/malignant classification to formal grade levels on the basis that all NETs have malignant potential.
It also introduced a change to the naming of mixed cell tumours from Mixed AdenoNeuroendocrine Carcinoma (MANEC) to Mixed Neuroendocrine Non-Neuroendocrine Neoplasms (MiNEN). A full explanation of MiNEN will follow but I would suggest the use of the term ‘Neoplasm’ has been chosen rather than ‘Carcinoma’ is because these neoplasms can be well or poorly differentiated.
It’s not possible at this time to acquire copies of the official output but I will keep this blog live.
The source material for the 2017 version of this article.
From leading Pathologist Dr Anthony Gill – Remember this is based on Endocrine Organs only but it will eventually apply to all. I am awaiting access to free documentation to update this article further – only ones I can currently find are not free!
Staging is the extent or spread of disease. Most types of cancer have 4 stages, numbered from 1 to 4 indicating a rising spread as the number is bigger. Often doctors write the stage down in Roman numerals, perhaps this is to stop any confusion between standard numbers used for Grades? So you may see stages written as I, II, III and IV. In addition to this standard method, there is also an agreed model known as TNM (Primary Tumour, Regional Node, Distant Metastasis) which is essentially a more detailed staging definition when combined with the Stage 1-4 model. Please note with TNM models, there could be different stage descriptions depending on the location of the primary tumour and similarly different TNM models for different tumour locations.
WHO 2017 changes
WHO 2017 has recommended enhancements to the TNM system mainly the use of additional suffixes indicating the extent of lymph node involvement. Details to follow when I can free access.
The following example shows the stage descriptions for a NET of the small intestine (the others are similar but worded accordingly for that part of the anatomy):
Stage I tumour is less than 1 cm in size and has not spread to the lymph nodes or other parts of the body.
Stage II tumour is greater than 1 cm in size and has started to spread beyond the original location, but has not spread to the lymph nodes or other parts of the body.
Stage III is any size tumour that has spread to nearby areas of the body and also to at least one lymph node.
Stage IV is any size tumour that has spread to one or more lymph nodes and has also spread to other, more distant areas of the body (such as the liver).
It’s also worth pointing out that Stage IV does not necessarily mean a cancer is more dangerous than other cancers of lesser stages. This is an important point for NETs where Stage 4 can be matched up with a low-grade tumour i.e. Stage 4 for lower grade NETs is very often not the ‘red flag’ it is for other more aggressive cancers. For example, doctors may surgically remove a Stage IV NET, while surgery might not help a patient with a cancer of a higher grade at such a late stage.
Sometimes doctors use the letters to further divide the number categories – for example, stage 2A or stage 3B. This is normally to clarify or provide more detail of the primary tumour size/invasion in conjunction with the TNM model.
You may also see something called Stage 0 which is for ‘Carcinoma in situ’. It means that there is a group of abnormal cells in an area of the body. However, the number of abnormal cells is too small to form a tumour and may, therefore, be currently classed as benign. The World Health Organisation (WHO) system does not appear to recognise Stage 0 for NETs.
The most generic model for TNM staging is below but please note this could be adjusted for particular types of NET.
Primary Tumor (T) TX: Primary tumor cannot be evaluated T0: No evidence of primary tumour Tis: in situ (abnormal cells are present but have not spread to neighbouring tissue; although not cancer, in situ may become cancer and is sometimes called preinvasive cancer)
T1, T2, T3 and T4 is a measure of the size of, and/or invasion/penetration by, the primary tumour and the wording varies between different NET sites. e.g. for a small intestinal NET:
T1 tumour invades mucosa or submucosa and size <=1 cm
T2 tumour invades muscularis propria or size >1 cm
T3 tumour invades subserosa
T4 tumour invades the visceral peritoneum (serosa)/other organs
Distant Metastasis (M) MX: Distant metastasis cannot be evaluated M0: No distant metastasis M1: Distant metastasis is present
You may occasionally see TNM staging be prefixed by lower case letters. The most commonly used prefix is ‘p’ simply meaning the grading has been confirmed by pathology. e.g. pT4 N1 M1
Specialists can combine the Stage to create a TNM – for example:
This slide will be updated when I get access to WHO 2017 or updated AJCC pubication.
A complex area and I hope I have condensed it sufficiently for you to understand enough for your purposes. Despite looking very scientific, it is not an exact science. There are many variables as there always are with Neuroendocrine disease. NENs can be very challenging for a pathologist even an experienced one who may not have encountered NENs before. However, it is an extremely important part of initial diagnosis and also when needed during surveillance. It is a vital tool used by Multidisciplinary Teams (MDT) in treatment plans and for prognostic purposes. If you need to learn further, I recommend this document:
If you are interested in this subject and have one hour to spare, there is a great video here from LACNETS worth watching.
I once met some fellow cancer advocates and the conversation turned to what inspired us to ‘do what we do’. When it came to my turn as the only Neuroendocrine Cancer patient, I was already prepared to regurgitate my usual ‘spiel’. As sometimes happens, a listener queried me with the words “Neuroendocrine – what’s that?“. Another focused on ‘Neuro‘ enquiring whether my nervous system or my brain had somehow become cancerous. Deja vu – here we go again!
Two days later, I was speaking to one of my online friends who was having similar problems explaining this cancer to family and friends. Again ‘Neuro‘ was proving difficult with the assumption that it’s somehow related to the brain. Technically not far from the truth but context is really important given that most people look at cancer in anatomical terms. As we know this can often lead to incorrect headlines for famous cancer patients.
I’ve struggled since 2010 to explain this disease in layperson terms. It’s actually one of the reasons for my ‘study’ and my blog. It’s getting easier, particularly when answering questions. However, if Neuroendocrine Cancer knowledge was an iceberg, I’d still be at the tip! I did write a post entitled Horrible Hormones which supports an explanation. You might like to read it– perhaps helpful to aid your overall understanding of this post.
The other difficult aspect of explaining Neuroendocrine Cancer is the extent of the Anatomy and Physiology of the Neuroendocrine system which appears in numerous parts of the body. I’ve written about this before at a time when I was fed up with newspaper reports and on-line articles implying that Neuroendocrine Cancer didn’t exist – e.g. by frequently describing Neuroendocrine Tumours of the Pancreas as Pancreatic Cancer and Neuroendocrine Tumours of the Lung as Lung Cancer. During some of my own verbal discussions, mention of the small intestine was frequently met with “so you have Bowel Cancer“. NO I DON’T! Good time to refresh yourself with my article The Human Anatomy of NET Cancer. This thinking needs to be challenged at every opportunity including while explaining to family and friends.
I’ve therefore decided to attempt a short, generic but still sufficiently detailed explanation of the word ‘Neuroendocrine‘ in relation to my Cancer. I suspect by the end of this article, it will not be as short as I had wished. I do like a challenge 🙂 Here goes:
The neuroendocrine system is made up of a network of cells that are distributed throughout the body. The word neuroendocrine refers to 2 qualities of these cells: they have a similar structure to nerve cells (neurons) and produce hormones like endocrine cells. Neuroendocrine cells release hormones into the bloodstream in response to chemical signals from other cells or messages from the nervous system. Basically hormones travel in the bloodstream and makes things happen in another part of the body.
These neuroendocrine cells are scattered throughout the body performing different roles based on location, e.g. Neuroendocrine cells in the digestive system regulate intestinal movements and the release of digestive enzymes
When Neuroendocrine tumours develop in these cells, they can not only then spread to other locations but they can also secrete excess amounts of hormones and substances which can cause an adverse effect on the body’s natural rhythm. A collection of these symptoms is known as a syndrome. There are several different syndromes depending on the location and type of Neuroendocrine Tumour.
The presence of the syndrome nearly always indicates the tumours are functional. Sometimes tumours are non-functional (i.e. they do not overly secrete excess hormones or cause symptoms), these non-functional types can be even more difficult to diagnose.
Most Neuroendocrine Tumours are slow-growing and therefore offer good outlook if identified as early as possible and treated. Even for metastatic patients, the outlook is relatively good with the right treatment and surveillance. Some are more aggressive behaving like adenocarcinomas and need a different approach to treatment.
I found it very difficult to write a short and generic explanation of the word ‘Neuroendocrine‘ in relation to cancer – no wonder I seem to spend 10 minutes verbally explaining to people and…… no wonder they sometimes look at me with glazed eyes 🙂 However, this is my offer. This is as brief as I can make it to provide understanding. I’ve cut out more than I’ve left behind and feel like I’m short-changing you! However, it needs to be basic and it needs to be short.
Explanations which comprise lists of complex and unpronounceable words each with their own constraints and variable meanings leads to chaos and people switching off. I could have just referred to one of the excellent publications on the web but this isn’t really practical when in an impromptu conversation with wide-eyed listeners. That said, I believe the combination of this post and (if you see light-bulbs) the other 2 linked posts within, is a good way to answer the question if someone is willing to listen (and read a short reference). You may therefore need to follow-up the ‘verbal’ with the ‘written’.
To summarise, I intentionally made this explanation as generic as possible. Trying to explain every single type of Neuroendocrine Cancer will confuse and tire the best listener. If I was using this today, I would add my own additional comment about where my tumours were found and what treatment I’ve had – this I can do without a script! However, if you think this explanation is of use when verbally explaining Neuroendocrine in relation to your cancer, please feel free to share my blog post to aid understanding.
Neuroendocrine – what’s that? I didn’t have a clue …… until I was diagnosed with it!
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 (currently) 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.