Can NETs be cured?

cure quote

OPINION:

“Cured” – In cancer, this word can evoke a number of emotions. Interestingly, not all these emotions will be as positive as you might think. If you want to spark a heated debate on a Neuroendocrine Cancer patient forum, just mention that you’ve been cured.

I’ve been living with Neuroendocrine Cancer for 8 years so I must be cured, right? Unfortunately not as straightforward as this, and I’m guessing this is the case for many cancers. Doctors clearly need to be careful when saying the word “cured‘ even if there is a small likelihood that a cancer will recur.  There’s plenty of ‘conservative’ and alternative terms that can be used, such as ‘stable’, ‘no evidence of disease (NED)’, ‘in remission’ or ‘complete response’.  However, I don’t see the latter two much in Neuroendocrine disease circles.

So with all these ‘ifs’ and ‘buts’, what exactly is a cure?

Answering this question isn’t a simple case of ‘yes’ or ‘no’, because it depends on the way that the term ‘cancer’ is defined. It should actually be viewed as an umbrella term for a collection of hundreds of different diseases. They all share the fundamental characteristic of rogue cells growing out of control, but each type of cancer, and each person’s individual cancer, is unique and comes with its own set of challenges.

That’s why it’s very unlikely that there will be one single cure that can wipe out all cancers. That doesn’t mean individual cases of cancer can’t be cured. Many cancers in fact already can be. Scientists aren’t actually on the hunt for a ‘silver bullet’ against all cancers, Quite the opposite. The more scientists get to know each type of cancer inside and out, the greater the chance of finding new ways to tackle these diseases so that more people can survive. Thanks to a much deeper understanding of cell biology and genetics, there exist today a growing number of targeted therapies that have been designed at a molecular level to recognise particular features specific of cancer cells. Along with chemotherapy, surgery and radiotherapy, these treatments—used singly and in combination—have led to a slow, but steady, increase in survival rates. You can definitely count Neuroendocrine Cancer in that category.

Cancer is seen today less as a disease of specific organs, and more as one of molecular mechanisms caused by the mutation of specific genes. The implication of this shift in thinking is that the best treatment for, say, colorectal cancer may turn out to be designed and approved for use against tumors in an entirely different part of the body, such as the breast. We’re certainly seeing that with certain targeted therapies and more recently with Immunotherapy.

Surely a cure is more possible if cancer is diagnosed earlier?

To a certain extent this is true for many types of cancer, not just for NETs.  In fact the same scientists did say ….”We detect those attacks when they’re still early, before the cancers have widely spread, at a time when they can still be cured simply by surgery or perhaps surgery and adjuvant therapy, which always works better on smaller tumors.”.  

What about Neuroendocrine Tumors (NETs)?  Clearly I’m not qualified to make such statements except to say that I am of the opinion that earlier diagnosis is better for any curative scenario.  When you read NET guidelines (ENETS/NANETS etc), the word ‘cure’ and ‘curative’ is mentioned in relation to surgery.  Bearing in mind that our most expert NET specialists are involved in the drafting of these guidelines, perhaps we should pause and think before dismissing these claims.  Having checked ENETS publications, I can see it’s related to certain conditions and factors such as localisation within the organ, tumour size, good resection margins, and a suitable follow-up surveillance.

Clearly with advanced disease, the cancer becomes incurable but treatment for many being palliative to reduce tumor bulk and reduce any symptoms and/or syndrome effects. Despite this, the outlook for metastatic NETs at the lower grades is good. While we’re talking about palliative care, do not confuse this with end of life, that is only one end of the palliative spectrum.  It can and is used at the earliest stage of cancer.

Immunotherapy will eventually cure cancer, right?

Immunotherapy will play a huge part in cancer treatment in the future, that we know.  But to suggest that it’s a cure is probably overstating its current success.  Neuroendocrine Cancer has not been forgotten – you can read more about Neuroendocrine Cancer and Immunotherapy here.

I heard the Oncolytic Virus at Uppsala is a cure for NETs?

There is currently no scientific evidence that the Oncolytic Virus (AdVince) can cure humans with Neuroendocrine Cancer.  So far it has only been proven in destroying neuroendocrine tumours in mice. The Oncolytic Viruses developed in Uppsala are now being evaluated in phase I clinical trials for neuroendocrine cancer.  If you’re not up to speed with this trial, read more here – Oncolytic Virus Uppsala

Isn’t prevention better than a cure?

This old adage is still relevant BUT latest thinking would indicate it is not applicable to all cancers.  Scientists claim that 66% of cancer is  simply a form of ‘bad luck’ and if the claim is accurate, it follows that many cancers are simply inevitable. The thinking suggests that random errors occurring during DNA replication in normal stem cells are a major contributing factor in cancer development confirming that “bad luck” explains a far greater number of cancers than do hereditary and environmental factors. This scientific thinking is a tad controversial so it’s worth remembering that even if, as this study suggests, most individual cancer mutations are due to random chance, the researchers also admit that the cancers they cause may still be preventable. It’s complex!

The newspapers are always talking about breakthroughs and cures for cancer?

Newspapers looking for a good headline will use words such as ‘cure’. Sadly, headlines are generally written by sub-editors who scan the article and look to find a ‘reader-oriented angle’ for the heading. They either can’t or don’t have time to understand what’s actually being said. Unfortunately this then leads to people sharing what is now a misleading article without a thought for the impact on those who are worried about the fact they have cancer and whether it can be cured or not.  There’s also a lot of fake health news out there – check out my article series about the problems with the internet and ‘Miracle Cures’.

To cure, they must know the cause?  

To a certain extent, that’s very accurate.  Have you ever wondered what caused your NETs?  I did ponder this question in an article here.  The only known cause of NETs is currently the proportion of patients with heredity syndromes – see my article of Genetics and Neuroendocrine Cancer.  Interestingly, the NET Research Foundation recently awarded funding to look at the causes of Small Intestine (SI) NETs (one of the most common types).  A scientific collaboration between UCL, Dana-Farber Cancer Institute, UCSF Medical Centre and the UCL Cancer Institute / Royal Free Hospital London. The team’s approach has the potential to identify inherited, somatic (non-inherited) genetic, epigenetic and infectious causes of SI-NETs.  The research is questioning whether SI-NETs are caused by DNA changes in later life or by aberrant genes inherited at birth; environmental influences or infectious agents – or is it a combination of all these factors?  Very exciting. Read more here.

What would a cure mean to those living with NETs?

This is something that has crossed my mind, even though I don’t believe it will happen in my lifetime.  I guess it would be good to get rid of the known remnant tumors left behind from my treatment (and any micrometastases currently not detectable).  However, many NET patients are living with the consequences of cancer and its treatment, including surgery, chemotherapy, biological therapy, somatostatin analogues, radionuclide therapy, liver directed therapy, and others.  Many of these effects would remain – let’s face it, a cure is not going to give me back bits of my small and large intestine, liver and an army of lymph nodes. So support for those living with NETs would need to remain despite a cure.

Summary

The emotional aspect of the word ‘cured’ seems to be an issue across many cancers and it’s certainly very controversial in NET circles.  The world has still not cured the many cancers that exist. But over the next five to ten years the era of personalised medicine could see enormous progress in making cancer survivable.  I think both doctors and patients need to take a pragmatic view on the ‘cured’ word and to end this article I wanted to share an interesting quote I found whilst researching.

cure quote

It’s been 5 years since I saw a scalpel (….but my surgeon is still on speed dial)

im-still-here

5 years ago today, I had a bunch of lymph nodes removed. Two separate areas were resected, only one was showing growth but both were showing up as hotspots on an Octreoscan.  I had known since shortly after diagnosis in 2010 that ‘hotspots’ were showing in my left ‘axillary’ lymph nodes (armpit) and my left ‘supraclavicular fossa’ (SCF) lymph nodes (clavicle area). Some 10 months previously, I had a major liver resection and 5 months prior to the liver resection, I had a small intestinal primary removed including work on some associated complications.  There had always been a plan to optimise cytoreduction of my distant metastases, it was just a matter of timing. I still can’t get my head round why metastases from a small intestinal NET managed to get to this area but not others!

Distant nodal metastasis treatment

A total of 9 nodes were removed from my left armpit (a very common operation for breast cancer patients). The surgeon had inspected the area and found some were palpable and my normally stable Chromogranin A marker was showing a small spike out of range.  During the same operation under general anaesthetic, an ultrasound directed SCF nodal ‘exploration’ was carried out.  When biopsied, 5 of the 9 resected axillary nodes were tested positive (Ki-67 <5) but the 5 SCF nodes removed were tested negative. The subsequent Octreoscan still lit up in the left SCF area but the lights on the left axillary area were ‘extinguished’. There is no pathological enlargement or pain in the left SCF area – so this is just monitored.

Side effects

Apart from a very faint scar in the left SCF area, there does not appear to be any side effects from this exploratory surgery.  The left axillary area cut is well hidden by hair growth but I do sense a lack of feeling in the area.  Additionally, I have a very mild case of lymphedema in my left hand which occasionally looks slightly swollen – the consequences of cancer and its treatment.  Fluid build-up, or post-operative seroma, can be a side effect of a lymphadenectomy.  In fact, within a month of the operation, I had to have circa 160mls of fluid removed on 4 occasions from my armpit.  It was uncomfortable and painful, resulting in additional time off work.  The surgeon used a fine needle aspiration to draw out the fluid, a painless procedure. It eventually cleared up and everything was back to normal.  The specialist said my left arm would be slightly more susceptible to infections and suggested to avoid using my left arm for blood draws and other invasive procedures and injuries.

Other close calls (“to cut or not to cut”)

I have a 19mm thyroid lesion which was pointed out to me in 2013. This has been biopsied with inconclusive results.  Although the thyroid is an endocrine gland, it looks like a non-NET problem so far. Thyroid nodules are in fact very common and statistically, 50-70% of all 50-70 year olds will have at least one nodule present (i.e. if you are in your 50s, there is a 50% chance you will have one nodule and so on). The vast majority will never bother a person while they live.  I attend an annual Endocrine MDT where this is monitored in close coordination with the NET MDT. It’s actually managed by the same surgeon who carried out the nodal work above.

I have a 3mm lung nodule, discovered in 2011. Apparently, lung nodules are a pretty common incidental finding with 1 per 500 X-rays and 1 per 100 CT scans finding them.  This is monitored and hasn’t changed since noted.

You may also be interested in my post “Neuroendocrine Cancer – to cut or not to cut”

I watch and wait but I also watch and learn.  Make sure you are under some form of surveillance.

Thanks for reading

Ronny Allan

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Surgery for NETs – Chop Chop

Carcinoid liver tumour debulking
Liver tumour debulking

At the end of 2014, I was feeling pretty good celebrating 4 years since my first ‘big’ surgery in 2010. It prompted me to write an article Surgery – the gift that keeps on giving. In that particlar article, I really just wanted to say I was grateful for the early surgical treatment and as I was just about to spend another Christmas with my family, I was reminiscing what a wonderful gift it was at the time. Other than some detail of the surgery, I didn’t get too technical, I just wanted to generate a thankful and festive mood. However, a recent private message from a subscriber prompted me to study the current benefits of surgery for Neuroendocrine Tumours (NETs) in more detail just to ensure my understanding was still in line with best practice.

It’s very well known that NETs can present a major challenge to physicians in their recognition and treatment requirements.  For example, NETs can cause various syndromes, not only for requiring treatment for primary and loco-regional tumours to minimise the risk of abdominal complications and future growth; but also for removal of tumour including liver and other metastases to palliate hormonal symptoms. Some tumours can be quite large and require extensive surgery to remove.

I searched reputable websites and European and North American NET treatment guidelines to find that surgical treatment of these tumours still appears to remain an important intervention, not just for curative treatment (where this is possible) but also for symptom palliation and survival. Although more treatment modalities are available than ever before (e.g. radiotherapy including PRRT, liver embolisation, liver ablation, somatostatin analogues and other new drugs, some with chemo combinations), surgery still appears to be the mainstay treatment to be offered when it is appropriate.  For some it isn’t appropriate or will be held in reserve for watch and wait scenarios or as ‘adjuvant’ treatment downstream. On paper, it appears to be the only current option for a curative scenario if the cancer is caught early enough.

I had an amazing surgeon with an impressive CV in Neuroendocrine disease.  He believes in early and aggressive surgery (within normal guidelines) and always in conjunction with other treatment modalities and only when required.  I found a video of one of his lectures which you may find useful.  Another surgeon who talks with knowledge and passion is Dr Pommier and one of his videos can be viewed here. I’m sure there are many others.   They are different characters but they both seem to believe in getting as much tumour out as early as possible and also emphasise that sometimes it can be too risky so the focus moves to other treatment.  Both presentations provide statistical evidence that debulking/cytoreductive surgery can often offer a better outlook even for those with advanced neuroendocrine disease.

I think I have a soft spot for surgeons – they also seem to love their job despite it being particularly ‘gory’.  On the subject of ‘gory’, I recently came across another surgical video which I found totally fascinating.  This one contains amazing footage of real surgery and if you are like me, you will find this very educational. It’s also fairly recent (2014) so perhaps offers more up to date techniques. It’s also a very well structured presentation. Some of you may have seen it before and some of you could even have even been at the presentation! If you don’t have time, skip forward to approximately ’19 minutes’ and watch them take out large and small tumours of the liver using a technique called enucleation!   (Click here to watch).

Hope you enjoyed this session as much as I enjoyed writing it!

Thanks for listening

Thanks for reading

Ronny

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Remember ….. in the war on Neuroendocrine Cancer, let’s not forget to win the battle for better quality of life!



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Neuroendocrine Cancer – Hormones

HormonesNET 2018

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

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

Serotonin

I used the example of Serotonin above 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.

Tachykinins

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

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

Kallikrein is a potent vasodilator and may account for the flushing and increased intestinal mobility.

Prostaglandins

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

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

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).

Endocrine Organs

Thyroid Gland

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.

Pituitary Gland

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.

Adrenal Glands

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).

Cortisol

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

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.

The pancreas is one of the ‘3 p’ locations often connected to Multiple Endocrine Neoplasia – MEN 1

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:

  • Diarrhea.
  • Indigestion.
  • 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).
  • Diarrhea.

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.
  • Fast heartbeat.

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.
  • Diarrhea.
  • 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.
  • Facial flushing.
  • 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.
  • Diarrhea.
  • Steatorrhea (very foul-smelling stool that floats).
  • Gallstones.
  • Yellowing of the skin and whites of the eyes.
  • Weight loss for no known reason.

Too much pancreatic polypeptide may cause:

  • belly pain.
  • an enlarged liver.

Testing hormones

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 a read 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.

Thanks for reading

Ronny

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