Recent Progress in NET Management – Positive presentation from Jonathan R Strosberg MD

jonathan-strosbergI recently wrote a blog called Neuroendocrine Cancer – Exciting Times Ahead! I wrote that on a day I was feeling particularly positive and at the time, I wanted to share that positivity with you. I genuinely believe there’s a lot of great things happening. Don’t get me wrong, there’s a lot still to be done, particularly in the area of diagnosis and quality of life after being diagnosed. However, this is a really great message from a well-known NET expert.

In an interview with OncLive, Jonathan R. Strosberg, MD, associate professor at the H. Lee Moffitt Cancer Center in Florida, discussed his presentation on NETs at a recent 2016 Symposium, and shed light on the progress that has been made in this treatment landscape.

OncLive: Please highlight some of the main points from your presentation.

Strosberg: The question I was asked to address is whether we’re making progress in the management of NETs, and I think the answer is unequivocally yes. Prior to 2009, there were no positive published phase III trials.

Since then, there have been 8 trials, 7 of which have reached their primary endpoints. So it’s been a decade of significant improvement. And even though none of these studies were powered to look at overall survival as an endpoint, we’re certainly seeing evidence of improvement in outcomes.

OncLive: What are some of the pivotal agents that you feel have impacted the paradigm in the past several years?

Strosberg: The first group is the somatostatin analogs. We use them to control hormonal symptoms like carcinoid syndrome, but with the CLARINET study, we now know that they substantially inhibit tumor growth.

The next significant drug we use in this disease is everolimus (Afinitor), an oral mTOR inhibitor, which is now approved in several indications based on positive phase III studies. The first was in pancreatic NETs and subsequently, based on the RADIANT-4 trial, it was also approved in lung and gastrointestinal NETs. So that was an important advance.

The next important category of treatment is radiolabeled somatostatin analogs, otherwise known as peptide receptor radiotherapy. The one that’s been tested in a phase III trial is lutetium dotatate, also known as Lutathera. It was tested in patients with progressive midgut NETs and showed a very substantial 79% improvement in progression-free survival, and a very strong trend toward improvement in overall survival, which we hope will be confirmed upon final analysis.

OncLive: Are we getting better at diagnosing and managing the treatment of NETs?

Strosberg: Certainly. I think pathologists are better at making the diagnosis of a NET, rather than just calling a cancer pancreatic cancer or colorectal cancer. They’re recognizing the neuroendocrine aspects of the disease, and doing the appropriate immunohistochemical staining.

We also have better diagnostic tools. We used to rely primarily on octreoscan, and in many cases we still do, but there is a new diagnostic scan called Gallium-68 dotatate scan, also known as Netspot, which has substantially improved sensitivity and specificity. It’s not yet widely available, but it is FDA approved and hopefully will enable better diagnosis as well as staging in the coming years.

And, with the increase in number of phase III studies, we’re developing evidence-based guidelines, which will hopefully lead to more standardization, although knowing how to sequence these new drugs is still quite challenging.

OncLive: With sequencing, what are the main questions that we’re still trying to answer?

Strosberg: If we take, for example, NETs of the midgut, beyond first-line somatostatin analogs, physicians and patients often face decisions regarding where to proceed next, and for some patients with liver-dominant disease, liver-directed therapies are still an option.

For others, everolimus is a systemic option, and then hopefully lutetium dotatate will be an option based on approval of the drug, which is currently pending. Knowing how to choose among those 3 options is going to be a challenge, and I think there will be debates. Hopefully, clinical trials that compare one agent to another can help doctors make that choice. It’s even more complicated for pancreatic NETs. Beyond somatostatin analogs, we have about 5 choices—we have everolimus, sunitinib (Sutent), cytotoxic chemotherapy, liver-directed therapy, and peptide receptor radiotherapy. It’s even more challenging in that area.

OncLive: Are there any other ongoing clinical trials with some of these agents that you’re particularly excited about?

Strosberg: There’s a trial that is slated to take place in Europe which will compare lutetium dotatate with everolimus in advanced pancreatic NETs, and I think that’s going to be a very important trial that will help us get some information on both sequencing of these drugs, as well as the efficacy of Lutathera in the pancreatic NET population, based on well-run prospective clinical trials. I’m particularly looking forward to that trial.

OncLive: Looking to the future, what are some of the immediate challenges you hope to tackle with NETs?

Strosberg: One area of particular need is poorly differentiated neuroendocrine carcinomas. That’s a field that’s traditionally been understudied. There have been very few prospective clinical trials looking at this particular population, and we’re hoping that will change in the near future. There are a number of trials taking place looking at immunotherapy drugs. If these agents work anywhere in the neuroendocrine sphere, they are more likely to work in poorly differentiated or high-grade tumors, in my opinion, given the mutational profile of these cancers. So that’s something I’m particularly looking forward to being able to offer these patients something other than the cisplatin/etoposide combination that goes back decades, and is of short-lasting duration.

See more at: http://www.onclive.com/publications/oncology-live/2016/vol-17-no-24/expert-discusses-recent-progress-in-net-management#sthash.ypkilX2A.dpuf

Thanks for reading

Ronny

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Neuroendocrine Cancer – tumour markers and hormone levels


blood tests

I think most people have had a form of medical testing at some point in their life, i.e. the sampling and testing of blood, urine, saliva, stool or body tissue. In a nutshell, the medical staff are just measuring the content of a ‘substance’ and then taking a view whether this is normal or not based on pre-determined ranges. These tests are normally done as a physician’s reaction to symptom presentation or maintenance/surveillance of an existing diagnosed condition. Sometimes, abnormal results will lead to more specialist tests.

In cancer, these tests are frequently called ‘markers’. Most tumour markers are made by normal cells as well as by cancer cells; however, they are produced at much higher levels in cancerous conditions. These substances can be found in the blood, urine, stool, tumour tissue, or other tissues or bodily fluids of some patients with cancer. Most tumour markers are proteins. However, more recently, patterns of gene expression and changes to DNA have also begun to be used as tumour markers.  Many different tumour markers have been characterized and are in clinical use. Some are associated with only one type of cancer, whereas others are associated with two or more cancer types. No “universal” tumour marker that can detect any type of cancer has been found.

markers

There are some limitations to the use of tumor markers. Sometimes, noncancerous conditions can cause the levels of certain tumor markers to increase. In addition, not everyone with a particular type of cancer will have a higher level of a tumour marker associated with that cancer. Moreover, tumour markers have not been identified for every type of cancer. Tumour markers are not foolproof and other tests and checks are usually needed to learn more about a possible cancer or recurrence.

I’d also like to talk about a group of associated tests, in particular, hormone levels as these tests are really important to help determine the type of Neuroendocrine Tumour.  NETs will sometimes oversecrete hormones and this can give clues to the type.  The constraints mentioned above apply to hormone levels and other tests to a certain extent.

What this article will not cover

Routine Testing – the post will not cover routine blood tests (i.e. complete blood count etc).  Although they may point to a problem, these tests do not necessarily indicate a particular type of NET without other supporting evidence.

Biopsy Testing – Technically, the Immunohistochemical ‘stains’ used in biopsy testing are tumour markers but I’ll not be discussing that today. I did cover the output of biopsies in my blog on NETs – Stages and Grades.

Genetic Testing.  This is very specialised but you may find my Genetics and NETs article is of interest.

Sequencing of marker testing – diagnosis

The sequencing of marker testing may have been different for many patients.  In my own experience, I had a biopsy and then the biochemical checks were carried out. So regardless of the results of my marker tests, I was to be diagnosed with NETs. Those with lengthy and difficult diagnostic phases will perhaps have had a different sequence with the biochemical markers providing evidence for further tests to formally diagnose.  Markers alone will normally not be enough for a diagnosis but they do, however, feed into the treatment plan and provide a baseline at diagnosis and for tracking going forward.

Interpreting test results – International/National/Regional differences

The use of markers tends to be different on an international basis, e.g. specific marker tests can be developed in-country by independent labs. Testing can also vary in the same country as in-country labs use different commercially available ‘testing kits’. Not all tests are available in all countries.

Reference ranges can be dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the tests to obtain the reference range if you do not have the lab report. Moreover, the ‘normal’ test range can vary from hospital to hospital, even within the same tests. I suspect clinical staff have their own versions of risk thresholds when dealing with test results. Even when results are just above or below, individual physicians can take their own view in a subjective manner. Testing is best done at the same lab each time if possible.

There’s a great website called LabTestsOnline which can describe each test. It’s peer-reviewed, non-commercial and patient-focused but just please note you should always refer to your own lab ‘normal ranges’ which will be printed on your test results.  For these reasons, you will not find reference ranges for the majority of tests described on this web site.  The link above will take you to the list of ‘country’ affiliated versions with specific information on a country basis.

Here’s some tips I always give people:

1 – Always try to get your own copy of results (preferably on paper) and track them yourself (I use a spreadsheet).

2 – When comparing results inside patient forums, always add the range and if possible, the unit of measurement (i.e. g/L, mmol/L, umol/L etc etc).  Failure to do this can at best confuse, and at worst frighten patients.  Compare apples with apples not with pears! (this is why it’s important to know the unit of measure and the reference range in addition to the figure).

3 – Don’t get too excited about rises if the test is still inside the normal range – normal is normal!

4 – Don’t get too excited about rises taking you just outside of normal range – your doctors are looking for bigger spikes.

5. Don’t get too excited about a single test result, your doctors are looking for trends, a single test result is not much to go on.

NET Markers

Although some routine blood markers (complete blood count etc) are useful in NETs, it’s pretty much impossible to cover these in any general detail.  I’m going to focus on tumor and hormone associated markers

There are many markers involved with NETs. Some do different jobs and some are just variants measuring the same thing (more or less efficiently). You may also see something called ‘gold standard’ in reference to NET Tumour markers. Although thinking is changing (more on this below) and can vary from country to country, it is generally accepted that Chromogranin A and 5HIAA are the gold standard markers for tumour bulk and tumour functionality respectively.  These gold standard tests may not be applicable to every type of NET, particularly 5HIAA. I’m also aware that US doctors are reducing the dependency on CgA and using Pancreastatin instead (although many are measuring both).

NETs are known to be heterogeneous in nature (i.e. consisting of or composed of dissimilar elements; not having a uniform quality throughout).  Whilst some markers can be used widely, it follows that there are many very specialist marker tests for individual types of NET.  I think this applies to 3 broad categories of NETs: Tumours known to potentially oversecrete Serotonin and and perhaps others (mainly midgut), Pancreatic NETs (or pNETs) secreting various hormones by type; and other less common types and/or syndromes which might be considered by some to be even more complex than the former two and in some cases there are big overlaps.

Another interesting thing about NET markers is that an undiagnosed patient may undergo several specialist tests to eliminate the many possibilities that are being presented as vague and common symptoms.  Sometimes this is necessary to eliminate or ‘home in’ on a tumour type or syndrome/hormone involved (it’s that jigsaw thing again!).

Markers too can be divided into broad categories, those measuring how much tumour is in your body and its growth potential and those measuring how functional (or not) those tumours are.  The latter can probably be expanded to measure/assess excess hormone secretion and syndromes.

The Anatomy

Certain tests can be anatomy related so to add context and to prevent big repetitive lists when using the terms ‘foregut’, ‘midgut’ and ‘hindgut’, you may find this graphic useful.

foregut midgut hindgut

Markers for measuring Tumour bulk or load/growth prediction

Chromogranin (plasma/blood test)

cgaChromogranin is an acidic protein released along with catecholamines from chromaffin cells and nerve terminals. This statement alone might explain why it is a good marker to use with NETs.  Depending on the test kit being used, you may see test results for Chromogranin A (CgA) and Chromogranin B (CgB) – the inclusion of CgB tends to be confined to Europe. There is also mention of Chromogranin C (CgC) in places but I’ve never heard of this being used in conjunction with NETs.

One of the disadvantages of CgA is that the results can be skewed by those taking Proton Pump Inhibitors (PPIs).  Many NET patients are taking PPIs to treat GERD (….and Zollinger-Ellison Syndrome). In the long-term, this has the result of increasing gastrin levels which can lead to an increase of CgA in the blood including for some months after discontinuing.  Opinions differ but many texts I found did suggest stopping PPIs for 2 weeks before the CgA blood test.  CgB is said not be as influenced by the use of PPI as CgA. In addition to the issue with PPIs, CgA levels may also be elevated in other illnesses including severe hypertension and renal insufficiency. CgB is also said to be more sensitive to Pheochromocytoma.

Elevated CgA is a constant and somewhat excitable discussion point on patient forums and not just because of the lack of unit of measurement use I discussed above. Some people get quite excited about a single test result.  I refer to Dr Woltering et al (ISI Book) where it clearly states that changes in CgA levels of more than 25% over baseline are considered significant and a trend in serial CgA levels over time has been proven to be a useful predictor of tumour growth (i.e. a single test result with an insignificant rise may not be important on its own).  Dr Woltering also gives good advice on marker tests when he says “normal is normal” (i.e. an increased result which is still in range is normal).

Here is a nice graphic explaining what else could be the cause of elevated CgA:

causes-of-cga-elevated

CgA appears to be a widely used tumour marker and is effective in most NETs (foregut, midgut and hindgut). It is also sensitive to Pheochromocytoma, particularly when correlated with a 131I-MIBG scan. Interestingly Chromogranin can also be used in the immunohistochemical staining of NET biopsy samples (along with other methods).

As for my own experience, my CgA was only elevated at diagnosis, remained elevated after intestinal surgery but returned to normal after liver surgery (indicating the effect of liver tumour bulk on results).  It also spiked out of range when some growth in a distant left axillary node was reported in Jan 2012.  Following a lymphadenectomy, it returned to normal again and has remained in range to this day.  It has been a good predictor of tumour bulk for me and I’m currently tested every 6 months.

Pancreastatin

In effect, this marker does the same job as CgA.  Interestingly, Pancreastatin is actually a fragment of the CgA molecule. There have been many studies (mainly in the US) indicating this is a more efficient marker than CgA, and not only because it is not influenced by the use of PPI.  It has also been suggested that it’s more sensitive than CgA and therefore capable of detecting early increases in tumour burden. It has also been suggested it can be an indication of tumour ‘activity’ (whatever that means). It is widely used in the US and some physicians will use it in preference to CgA (…..although from what I read, CgA also seems to be tested alongside).  I’m starting to see this mentioned in the UK.

Neurokinin A (NKA)

This is not a well publicised test. However, it is something used in USA but I’d like to hear from others to validate its use elsewhere.  In a nutshell, this test, which only applies to well differentiated midgut NETs, appears to have some prognostic indication.  I discovered this test in the ISI NET Guidance and it’s backed up by a study authored by names such as Woltering, O’Dorisio, Vinik, et al.  This is not a one-off test but one designed to be taken serially, i.e. a number of consecutive tests.  These authors believe that NKA can also aid in the early identification of patients with more aggressive tumors, allowing for better clinical management of these patients.  NKA is sometimes called Substance K.

Neuron-Specific Enolase (NSE)

In patients with suspected NET who have no clear elevations in the primary tumor markers used to diagnose these conditions, an elevated serum NSE level supports the clinical suspicion.

Markers for measuring Tumour functionality/hormone/peptide levels

So far, I’ve covered basic tumor markers which have a tumor bulk and/or prognostic indication.  This section is a slightly more complex area and many more tests are involved. There’s often a correlation between CgA/Pancreastatin and these type of markers in many patients i.e. a serial high level of CgA might indicate a high level of tumour bulk and therefore increased production of a hormone in patients with a syndrome or oversecreting tumor. However, it frequently does not work out like that, particularly when dealing with non-functioning tumours.

The type of marker for this element of NET diagnosis and surveillance will vary depending on the type of NET and its location (to a certain extent).  Like tumour bulk/growth, there might be different options or test variants on an international basis. There are too many to list here, so I’ll only cover the most common.

Serotonin Secreting Tumors

There are a few markers in use for measuring the functionality of this grouping of tumours. This tumour group has a tendency to secrete excess amounts of the hormone Serotonin although it differs depending on the area of the primary. For example, hindgut tumours tend to secret lower levels than foregut and midgut and therefore this test may present within range.  Please also note there may be other hormones of note involved. The antiquated and misleading term ‘Carcinoid’ is sometimes used as a descriptor for these tumours and more and more NET scientific organisations and specialists are now avoiding use of this term.

lug-the-jug
Lug the Jug

5HIAA.  5HIAA is a metabolite of Serotonin thus why it’s a useful thing to measure to assess functionality in this grouping of tumours. 5HIAA is actually the ‘gold standard’ test for functioning serotonin secreting tumours. It’s a key measure of the effects of carcinoid syndrome and the risk of succumbing to carcinoid heart disease.  However, there are two methods of testing:  Urine and Plasma.  The rather obvious key difference between the two is practicality. With the 24 hour urine, there are two key issues: 1.  The logistics (i.e. lug the jug).  2. Fasting for up to 3 days prior to the test (4 if you count the day of the test). There are numerous variations on the fasting theme but most labs tend to say not to eat at least the following foods that contain high levels of serotonin producing amines: avocados, bananas, chocolate, kiwi fruit, pineapple, plums, tomatoes, and walnuts.  Some lists contain additional items. With the plasma version, the fasting period is reduced to 8 hours (although I’ve seen some labs increase that to 10 or 12). There are also medicinal limitations including drugs that can also alter 5-HIAA urine values, such as acetanilide, phenacetin, glyceryl guaiacolate (found in many cough syrups), methocarbamol, and reserpine. Drugs that can decrease urinary 5-HIAA levels include heparin, isoniazid, levodopa, monoamine oxidase inhibitors, methenamine, methyldopa, phenothiazines, and tricyclic antidepressants. Patients should talk to their doctor before decreasing or discontinuing any medications. Taking 5HTP supplements are possibly not advised either prior to the test either.

As for my own experience, my 5HIAA (urine) was elevated at diagnosis only returning to normal after removal of my primary and commencement of Lanreotide. It has been a good measure of tumour functionality for me and I’m currently tested every 6 months.

Other tests for the tumour subgroup include but not limited to:

Serum Serotonin (5-HydroxyTryptamine; 5-HT).  Firstly let’s deconflict between 5HIAA above and the serotonin (5-HT) blood test.  5HIAA is a metabolite of serotonin but the serotonin test is a measure of pure serotonin in the blood.  Morning specimens are preferred and this is a fasting test (10-12 hours).  There is always debate on forums about Serum Serotonin results.  I have Dr Liu on record as saying “a high serotonin level measured in the blood in isolation really isn’t that dangerous. It’s the 5HIAA (a breakdown product of serotonin, which is easily measured in the blood and urine) that is considered to be more indicative of persistent elevated hormone. It’s this test that is most closely related to the carcinoid heart disease”.

Substance P.   A substance associated with foregut and midgut tumours.  It is a vasoactive protein that can cause wheezing, diarrhea, tachycardia, flushing

Histamines – Usually associated with foregut tumors. Appears to be involved in patchy rashes and flushing.  The advice in the ISI NET book is no anti-histamine medication to be taken for 48 hours prior to blood draw.

Gastric NETs (Stomach)

Testing will be different depending on the Type:

  • Type 1 – Typical Low Grade, tends to be caused by atrophic gastritis.
  • Type 2 – Atypical Intermediate Grade and tends to be caused by gastrin secreting tumours.  Type 2 normally needs a check for MEN1/Zollinger-Ellison Syndrome.
  • Type 3 – Tend to be larger and more aggressive tumours.

The key makers are CgA and Gastrin although Gastrin may not be elevated in Type 3. Gastrin ph is useful to differentiate between Type 1 and Type 2.  5HIAA can be considered but Carcinoid Syndrome is rare in Gastric NETs.

NETs of the Pancreas (pNETs)

pancreatic-cells
There are many different types of cells in the pancreas

pNETs can be very difficult to diagnose and not only because they share some presentational similarities to their exocrine counterparts.  Some pNETs actually comprise tumours arising in the upper part of the duodenum (small intestine) close to the Pancreas. Moreover, more than half of pNETs are non-functional which increases the difficulty in suspecting and then finding the tumours.  However, where there is clinical presentation or suspicion, these symptoms can lead to the appropriate testing to support the output of scans. The fasting gut profile mentioned above can be useful in identifying the offending hormones when the type of NET is not yet known.

Gut Hormones (Glucagon, Gastrin, VIP, Somatostatin, Pancreatic Polypeptide)

A gut hormone screen is used for the diagnosis of a variety of endocrine tumours of the pancreas area. Analysis includes gastrin, VIP, somatostatin, pancreatic polypeptide, and glucagon, but there may be others depending on processes used by your ordering specialist or hospital.

Notes:

1. You may see this referred to as a ‘Fasting Gut Profile’ or a ‘Fasting Gut Hormone Profile’.

2.  The individual hormones measured seem to differ between hospital labs.

3.  The fasting conditions also vary between hospitals and labs but all agree the conditions are critical to the most accurate results. Always ask for instructions if you’re offered this test.

The gastrin test is usually requested to help detect high levels of gastrin and stomach acid. It is used to help diagnose gastrin-producing tumours called gastrinomas, Zollinger-Ellison (ZE) syndrome, and hyperplasia of G-cells, specialised cells in the stomach that produce gastrin. It may be measured to screen for the presence of multiple endocrine neoplasia type I (MEN) It may be used if a person has abdominal pain, diarrhoea, and recurrent peptic ulcers. A gastrin test may also be requested to look for recurrence of disease following surgical removal of a gastrinoma.

Vasoactive intestinal peptide (VIP) measurement is required for diagnosis of pancreatic tumour or a ganglioneuroma which secretes VIP. Administration of VIP to animals causes hyperglycaemia, inhibition of gastric acid, secretion of pancreatic bicarbonate and of small intestinal juice, and a lowering of systemic blood pressure with skin flush. These features are seen in patients with a tumour of this type which is secreting VIP.

Glucagon is measured for preoperative diagnosis of a glucagon-producing tumour of the pancreas in patients with diabetes and a characteristic skin rash (necrolytic migratory erythema).

Pancreatic polypeptide (PP) production is most commonly associated with tumours producing vasoactive intestinal polypeptide and with carcinoid syndrome and, less commonly, with insulinomas and gastrinomas.

When secreted by endocrine tumours, somatostatin appears to produce symptoms similar to those seen on pharmacological administration, i.e. steatorrhoea, diabetes mellitus and gall stones.

There are several types of pNETs, each with their own syndrome or hormone issue.  When they are suspected due to the presentational symptoms, the markers that could be used are listed below.  These types of tumours are complex and can be related to one or more syndromes.  A patient may be tested using multiple markers to include or exclude these.  Depending on other factors, some physicians may recommend additional marker testing in addition to the most common types below.

Insulinoma – Insulin, Proinsulin, C-peptide

Gastrinoma– Gastrin, Gastrin pH

Glucagonoma – Glucagon, Insulin, Pancreatic Polypeptide (PP), Adrenocorticotropic hormone (ACTH)

VIPoma – Vasoactive Intestinal Polypeptide (VIP), Electrolytes (due to profuse diarrhea)

Somatostatinoma – Somatostatin (plasma somatostatin like immunoreactivity)

PPoma – Pancreatic Polypeptide (PP)

Other NETs/Syndromes

Pheochromocytoma/Paraganglioma – Adrenaline-producing tumours. Plasma and urine catecholamines, plasma free total metanephrines, urine total metanephrines, vanillylmandelic acid (VMA)

Medullary Thyroid Cancer. Medullary thyroid cancer (MTC) starts as a growth of abnormal cancer cells within the thyroid – the parafollicular C cells. In the hereditary form of medullary thyroid cancer (~20% of cases, often called Familial MTC or FMTC), the growth of these cells is due to a mutation in the RET gene which was inherited. This mutated gene may first produce a premalignant condition called C cell hyperplasia. The parafollicular C cells of the thyroid begin to have unregulated growth. In the inherited forms of medullary thyroid cancer, the growing C cells may form a bump or nodule in any portion of the thyroid gland.  Unlike papillary and follicular thyroid cancers, which arise from thyroid hormone-producing cells, medullary thyroid cancer originates in the parafollicular cells (also called C cells) of the thyroid. These cancer cells make a different hormone called calcitonin, which has nothing to do with the control of metabolism in the way  thyroid hormone does.  The other test often seen in MTC is Carcinoembryonic Antigen (CEA). CEA is a protein that is usually found in the blood at a very low level but might rise in certain cancers, such as medullary thyroid cancer. There is no direct relationship between serum calcitonin levels and extent of medullary thyroid cancer.  However, trending serum calcitonin and CEA levels can be a useful tool for doctors to consider in determining the pace of change of a patient’s medullary cancer.

[please note there are extremely rare occurrences of elevated calcitonin from places outside the thyroid – read more here.

Parathyroid– Parathyroid hormone (PTH), Serum Calcium.  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 – see MEN below.

Pituitary/Cushings – Adrenocorticotropic hormone (ACTH), Cortisol.

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.

Adrenocorticotropic hormone (ACTH) 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. ACTH is secreted in several intermittent pulses during the day into the bloodstream and transported around the body. Like cortisol (see below), levels of ACTH 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 ACTH are mainly due to the increase in cortisol levels which result. Higher than normal levels of ACTH may be due to:

Cushing’s disease – this is the most common cause of increased ACTH. It is caused by a tumor in the pituitary gland (PitNET), which produces excess amounts of ACTH. (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.

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.

A tumour outside the pituitary gland, producing ACTH (also called ectopic ACTH). With NETs, this is normally a pNET, Lung/Bronchial NET or Pheochromocytoma.

Multiple Endocrine Neoplasia (MEN).  Please note MEN is a group of distinct syndrome not a tumor.  Complex area and tends to be multiple instances of some of the tumours above.  For a breakdown of MEN types and locations, check out my MEN blog ‘Running in the Family’

Carcinoid Heart Disease(CHD) (Hedinger syndrome)  I’m not really talking directly about a tumour here but thought it would be useful to include a blood test called NT-proBNP.  I’ve left a link to my CHD article in the paragraph heading for those who wish to learn more about CHD in general.  For those not offered an annual Echocardiogram or are ‘non-syndromic’ there is a screening test that can give an indication of any heart issue which might then need further checks.

The Future – Molecular Markers?

This is testing using DNA and genes.  Exciting but complex – check out this article which involved some NETs.

Tumour Markers and Hormone levels – complex subject!

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Serotonin – the NET effect

A team of researchers from Case Western Reserve University School of Medicine have used high-powered microscopes for the first time to view serotonin activating its receptor

Background

I’d never heard of Serotonin until I was diagnosed with Neuroendocrine Cancer in 2010.  It is frequently discussed, often with contrasting views from the respondents. One common assumption/question is that it is responsible for many things that can go wrong with Neuroendocrine Cancer patients who have serotonin-producing tumours. “It’s the hormones” is an easy assumption to make or an easy answer to give in response to a complex set of circumstances.  It’s difficult to get a definitive answer and the science behind the behaviour of our hormones isn’t really 100% tied down.

You may see serotonin referred to as a ‘neurotransmitter’, a ‘chemical’ and a ‘hormone’ – this is complex but it is my understanding that it can add context in respect the role/location of the serotonin, e.g. chemical and hormone are essentially synonymous and are endocrine related whereas neurotransmitter is concerned with the nervous system (the neuro in neuroendocrine) and the brain (more on this below). Consequently, I’ll keep this as basic as I can (author’s note on completion – it was not easy!).

Serotonin and NETs

One thing which is widely accepted and agreed…… Serotonin is definitely involved in Neuroendocrine Tumours, in particular, those resulting in carcinoid syndrome which can manifest as a number of symptoms including but not limited to flushing and diarrhea.  Although serotonin is one of the main ‘hormones’ released in excess by certain NETs (mainly midgut), it is not thought to be the main culprit behind some of the symptoms produced by Carcinoid Syndrome.  For example, flushing, the most common symptom (and a cardinal one) is thought to be caused by a number of hormones/peptides – too many to list but the main ones are histamine (particularly foregut), tachykinins (Substance P), bradykinins, prostaglandins …….. and I’m sure serotonin’s in there too!  It does, however, appear to be massively guilty in causing carcinoid syndrome diarrhoea, desmoplasia, and carcinoid heart issues.

Where does Serotonin come from?

Serotonin’s technical name is 5-hydroxyltryptamine (5-HT).  It is converted from 5-Hydrotryptophan (5-HTP) which is also known as oxitriptan. 5-HTP is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of serotonin (…..and melatonin) from tryptophan. Tryptophan is interesting as that brings in one of the missing pieces of the jigsaw – food!  Tryptophan cannot be manufactured in the body, it must be brought in via diet. There is no serotonin in food, it is only manufactured in the body.

Tryptophan in food enters the body and serotonin is created by a biochemical conversion process which combines tryptophan (essentially a protein) with tryptophan hydroxylase (TPH), a chemical reactor. I suspect other substances might be involved in that process.  There are two forms of tryptophan hydroxylase – TPH1 and TPH2, which are encoded on two independent genes. TPH1 is linked to peripheral serotonin while TPH2 is related to brain serotonin.

While serotonin cannot cross the blood-brain barrier, tryptophan can, and once there, almost all of it is converted to serotonin. Unlike, peripheral setotonin where only a small percentage is used to generate serotonin. Just to emphasise that NET dietitians do not say to avoid foods containing tryptophan other than at the time of marker testing (see below and nutrition Blog 4). When you look at the role in brain serotonin, this might have an adverse effect. 

Are you happy with your serotonin?

Serotonin Inhibitors

The introduction of Somatostatin analogues (SSAs) such as Octreotide and Lanreotide, help reduce the secretion of “tumour-derived serotonin”  by binding to its receptors on the outside of the cell.  If you ever wondered why receptors are important, please check out my blog on this subject (click here).

I mentioned tryptophan hydroxylase (TPH) above and that is actually very interesting as this is how Telotristat Ethyl (XERMELO) is able to help with the symptoms of Carcinoid Syndrome diarrhea (not adequately controlled by SSAs) or where patients are unable to be treated by somatostatin analogues for whatever reason. It’s a potent inhibitor of TPH which will disrupt the manufacturing of tumour-derived serotonin. There is also evidence that it can help reduce the effects or halt the growth of the fibrosis leading to carcinoid heart disease.  Slight digression but useful to aid/enhance understanding at this point.  Read about Telotristat Ethyl here.

Serotonin and the Brain

There is constant discussion and assumption that serotonin-producing tumours are somehow causing depression, anxiety and rage.  Not as simple as that, it’s way more complicated.  Certain NETs can overproduce serotonin in the gut but the issues concerning depression and anxiety are normally associated with low levels of serotonin in the brain.

“Cancer anger” is a normal response to fear, despair and grief – a range of feelings which cancer brings into our lives. It can show as frustration, irritability, emotional withdrawal or aggression. You can feel it whether you have been diagnosed or you are a relative or friend. Cancer anger can happen at any stage of the illness, even years after treatment. I know that many people with cancer suffer from depression, anxiety and anger but they do not all have serotonin-producing tumours.  What they do have is a life threatening and/or life changing condition which is bound to have an effect on mind as well as body.  Hormones including Serotonin are natural substances found in the body and not just there to service NETs.

Serotonin is separately manufactured in the brain (~10%) and in the gastrointestinal tract (~90%).  The serotonin in the brain must be manufactured in the brain, it cannot be directly increased or reduced external to the brain, i.e. it cannot be directly reinforced by gut serotonin (peripheral serotonin). It follows that ‘brain serotonin’ and ‘gut serotonin’ are held in separate stores, they are manufactured in those stores and remain in those stores – there is no cross-pollination. This is managed by something called the blood-brain-barrier (BBB). Therefore, excess serotonin from NETs does not infiltrate the brain. As low-level of ‘brain serotonin’ is often linked to depression, it also follows that it’s possible to have high levels of serotonin in the gut but low levels in the brain.

My simple way of thinking about such things as outlined above, is that low levels of tryptophan in the brain might be contributing to low levels of serotonin in the brain.  To clarify that, I researched the reasons why there could be low serotonin in the brain. First, let’s dismiss any connection that the type of anti-depressant called Selective serotonin reuptake inhibitors (SSRIs) is involved. It’s thought that SSRIs work by increasing serotonin levels in the brain. Serotonin is a neurotransmitter (a messenger chemical that carries signals between nerve cells in the brain). We already discussed that it’s thought to have a good influence on mood, emotion and sleep. After carrying a message, serotonin is usually reabsorbed by the nerve cells (known as “reuptake”). SSRIs work by blocking (“inhibiting”) reuptake, meaning more serotonin is available to pass further messages between nearby nerve cells. So tryptophan or peripheral serotonin are not really involved.

It would be too simplistic to say that depression and related mental health conditions are caused by low serotonin levels (in the brain), but a rise in serotonin levels (in the brain) can improve symptoms and make people more responsive to other types of treatment, such as Cognitive Behaviour Therapy (CBT).  It’s also too simple to suggest that NET patients get depression and anxiety due to all the “hormones” these tumours produce.  Of course hormones can be involved in depression and anxiety but hormones aren’t their just for NET patients.  Cancer patients without hormone secreting tumours also get anxiety and depression so it’s possible that NET patients can get depression and anxiety in the same way.

It should also be noted that the precursor to serotonin, tryptophan, does pass through the BBB and it is therefore possible that tryptophan depletion can lead to less availability in the brain for the manufacture of brain serotonin.  Tryptophan depletion can be caused by dietary restrictions (i.e. lack of tryptophan foods) and also by the effects of certain types of tumours as excess serotonin is made leading to less availability of tryptophan.  Both could lead to low serotonin in the brain as less tryptophan gets there. It follows that foods containing tryptophan remain important in order to help maintain normal brain serotonin levels.

Measuring Serotonin levels

Measuring levels of serotonin is important in both diagnosis and management of certain NETs – although it’s probably sensible to test all potential NET patients during diagnosis when the type of tumour is not yet known.  Testing for tumour markers will differ between countries and within countries but the most common standard for testing Serotonin appears to be 5-HIAA (5-hydroxyindoleacetic acid) either via a 24-hour urine test or via a plasma version (mainly used in USA but now creeping into UK).  5-HIAA is the output (metabolite) of 5-HT (Serotonin). Not to be confused with the less reliable ‘serum serotonin’ which is a different test.

Another frequently asked question about serotonin tests is whether they are testing the amount in the brain or the gut. The answer is …… they are testing the levels in the blood. Furthermore, if you are measuring serotonin as an indicator for Carcinoid Syndrome, it has to be remembered that the majority of serotonin is in the gut, so even if serotonin levels in the brain were being measured alongside the gut levels, I don’t believe it would  influence the result in any significant way (but I have no science to back that up). It also has to be remembered that serum serotonin and 5HIAA are not absolute tests, they are not 100% sensitive, they are simply indicators of a potential problem. There are methods of measuring brain serotonin but it is very complex and beyond the purposes of this article.  However, I would just add that it is the reuptake of Serotonin in the brain (plus some other stuff) that can cause depression, not the actual level or amount in the brain.

I intentionally did not mention the other common test (Chromogranin A) or other markers as they are measuring different things but you can read about in my Testing for Markers blog.

Serotonin Video with myself and Dr Mike Morse

I made a video in 2019 with Dr Mike Morse sponsored by Lexicon Pharmaceuticals, Inc.  It’s all about Carcinoid Syndrome with a slant towards hormones, in particular Serotonin. Entitled “Likely Suspects: How Hormones May Lead to Carcinoid Syndrome – What People Living With Carcinoid Syndrome Need to Know”

You need to register to watch although some of you will already be registered and just need an email to login to see the this webcast. The one I’m featured in is the latest in a series on the subject and I’d like to break the record for views please! Please help me achieve this 💙 I would also love to get your feedback and sincerely hope you will find the time to listen in.  Please also find the time to complete the survey at the end.  Thanks

Click on the link here: www.CarcinoidWebcast.com

Don’t forget to press the play button and ensure your sound is turned up, particularly on mobile devices.

webcast morse allan

Summary

I did say it was a difficult jigsaw!

Thanks for reading

Ronny

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Neuroendocrine Cancer Nutrition Series Article 3 – Gut Health

OPINION.  Nutritional issues are one of the biggest challenges affecting most Neuroendocrine Cancer patients.  It is also a key factor in maintaining a decent quality of life and for most countries without adequate NET Specialist Dietitian support, it remains an unmet need. In this article, I’m discussing the use of probiotics to combat the potential issue of small intestine bacterial overgrowth (SIBO) in Neuroendocrine Tumours.  

When I first indicated this nutrition series was under construction, a few people got quite excited anticipating me to produce advice on what to eat.  However, that was never my intention. What people should or should not eat is such a varied problem (or solution?) that anything I said would only really be of help to those for whom it worked – this area is not an exact science. I’ve seen several ‘what to or not to eat’ publications/articles out there aimed at NET patients; some more up to date than others – all I would say is to interpret them carefully.

What my nutrition series actually covers is what causes the nutritional related issues and to a certain extent, try to work out how to tell if these issues are caused by either treatment or an associated syndrome, leaving fellow patients to make up their own minds about what to eat; or arm themselves with the necessary knowledge whether this applies to them or not.

The first two articles in the series were Article 1 – Vitamin and Mineral Challenges and Article 2 – Malabsorption. These remain popular and have a constants stream of views – no surprises as these are well known side effects of many types of NETs…… or at least they should be well known.

This particular article “Gut Health” is not as ‘clear cut’ or simple as the first two and I suggest you read Articles 1 and 2 first if you are not familiar with the issues.  Again I’m grateful to Tara Whyand (NET Specialist Dietician and researcher from Royal Free London) for some of the input below. Although I marked this with ‘Opinion’, some of it has references but I still decided to use ‘Opinion’ as the science is not yet 100%.

What is the “Gut” ?

When I first met my surgeon, I found one of his favourite words was ‘Gut‘.  Like me before diagnosis, many of you will have heard or used the word but in an intentionally non-medical context, e.g.  guts (bravery), ‘gut feeling’ or ‘gut instinct’ (intuition). I’ll return to that theme later but when you look at these contextual uses of the word, it’s no surprise why some scientists refer to our gut as a ‘second brain’.

I always thought the gut referred to just the ‘belly’ area but in medical parlance, the gut has a much bigger geography.  It is sometimes used interchangeably with the term Gastrointestinal (GI) Tract and stretches from the throat to the anus and is responsible (in the most general terms) for food intake, digestion/absorption,  waste processing and finally waste ejection.  NET patients should be familiar with the terms ‘foregut’, ‘midgut’ and ‘hindgut’ which are sometimes used to define the embryological origin and grouping of Neuroendocrine primary tumours, although the boundaries and constituent parts can vary from site to site.  The inclusion of certain anatomical locations as a sub-section of the gut is clearly for convenience rather than anatomical accuracy (e.g. Lung).

This is a massive subject but I wanted to ‘cut to the chase’ in this article and focus on the use of probiotics to combat the potential issue of small intestine bacterial overgrowth (SIBO) in Neuroendocrine Tumours.  The symptoms and signs of SIBO can be similar to they symptoms and side effects of treatment that many patients report anecdotally on patient forums.  I also found the science is complex and not really 100% tied down.

Probiotics

One of the first pieces of advice I was given after my initial surgery was to take probiotics – to keep up my stocks of ‘good’ bacteria.  I didn’t really understand why, I just complied. I started with the liquid drinks you can buy in most supermarkets and supplemented this by eating bioactive yoghurt.  I didn’t really notice any difference from either but the yoghurt was nice to eat!

Tara Whyand then confirmed this advice when I first met her in 2012 at a NET Patient conference.  In 2013 when I started looking for a new normal, I realised that the supermarket drinks and yoghurts were simply not enough good bacteria for my ‘new plumbing’, and decided to take a high-grade daily capsule containing 5 billion friendly bacteria multiple strains (Tara does recommend at least 2 billion and multiple strain).  Within weeks I was noticing a difference in bowel motility although I confess to changing other elements of my lifestyle at the same time given that I was embarking on finding my new normal.  Nonetheless, I sense probiotics are helping and I won’t be reducing or stopping them any time soon.  If you look at several NET specific dietician/nutrition presentations, most appear to promote the use of probiotics for NET patients.

Bacteria

One of the terms you find in this complex area is the ‘human gut microbiota‘, sometimes known as ‘gut flora‘. Our ‘gut’ harbours a complex community of over 100 trillion microbial cells, approx 3% of our body mass! The human gut microbiota is known to have an influence on every part of our body (including the brain…..) and disruption of this ‘community’ has been linked with several gastrointestinal conditions such as Inflammatory Bowel Disease (IBD) and obesity.

Probiotics are said to help keep the balance and mix of bacteria stable within the gut which can be affected by many different factors, including the use of antibiotics, aging, illnesses (such as IBD), following infective gastroenteritis and (of interest to NET patients) after cancer treatment or gastrointestinal surgery. {1}  Incidentally, the reference here is authored by Tara Whyand and Professor Martyn Caplin (a Neuroendocrine Tumour expert who also happens to be a Gastroenterologist). Useful reading if you have any of the conditions in the report or have had gut surgery (or like me you are a total geek!).  They are also frequently used in Irritable Bowel Syndrome (IBS).

Small Intestine Bacterial Overgrowth (SIBO)

Another interesting area of research into something called Small Intestinal Bacterial Overgrowth (SIBO), a condition where the small intestine is populated by an abnormal amount and/or types of bad bacteria. It follows that probiotics (good bacteria) may be useful in combatting this by helping to maintain balance.

So how does SIBO potentially and specifically affect NET patients?

  • It can be caused or exacerbated by abdominal surgery to stomach, duodenum, pancreas or via whipples, small & large intestine,
  • poorly controlled diabetes,
  • the long-term use of Proton Pump Inhibitors (PPI) (e.g. omeprazole and lansoprazole, etc). Several studies link to these drugs including this one,
  • possibly long term use of antibiotics which can kill good bacteria.Some evidence of surgical involvement can be found here – this link – particularly the bit about the prevalence of patients who have had an “abdominal surgery” or an “Ileocaecal valve resection”.  I guess that would include many NET patients?  (this is a big article so just focus on table 1 near the beginning).

Symptoms vary for everyone from watery diarrhoea suddenly starting 20 times a day to just bloating and wind in both directions, to nothing at all.  These symptoms are regularly reported by patients so working out the root cause might need some professional help.

Is there any testing for SIBO?

There is a test to check for SIBO is called the Hydrogen breath test. This test uses lactulose ingestion to measure the hydrogen in the breath. If SIBO is diagnosed, treatment is normally via antibiotics. However, advice is to leave a 2 hour gap between taking probiotics and antibiotics and a high dose multi-strain probiotic should be applied.  Our friend Tara has done some work on this alongside Professor Martyn Caplin which was featured at ENETS 2017.

ENETS Research – Assessment of Small Intestinal Bacterial Overgrowth (SIBO) in NET Patients Abstract #1698

Introduction: SIBO is not uncommon in NETs. Hydrogen Breath testing (HBT) using glucose may be more sensitive to proximal SIBO as glucose rarely reaches the colon. Many NET patients are likely to have distal SIBO however, as factors such as ileocecal valve removal apparently increase distal SIBO risk. Thus glucose BT alone may limit sensitivity for detecting SIBO in some NET diagnoses.

Aim(s): Assess likely risk factors for SIBO. Assess sensitivity of additional lactulose HBT and CH4 BT.

Materials and methods: Retrospective data (n=55) of NET patients undergoing HBT was examined. Twelve patients (12/55) who tested negative for glucose HBT but continued to have diarrhoea +/- wind had repeat BT using lactulose. These patients had both H2 & CH4 BT.

Results:
Midgut NET diagnoses were most frequently referred for BT (n=43, 78%). Twenty four (24/55, 44 %) had prior right hemicolectomy. Ten (10/24 ,42%) of those were SIBO positive. Ten patients were positive for HBT prior to being given the glucose substrate, they all had abdominal surgery in the past. Twelve patients who tested negative for glucose HBT had repeat testing using lactulose and measured both H2 and CH4 production. This led to an additional 3 (25%) positive results.

Conclusion:
Abdominal surgery, especially right hemicolectomy increases the likelihood of a positive glucose HBT. Glucose may still be sensitive in those with risk factors for distal SIBO. Additional lactulose use with H2 and CH4 measurement increases the sensitivity in diagnosing SIBO.

Conference:
14th Annual ENETS conference (2017)
Presenting Author: Tara Whyand

Keywords: nets, sibo, dysbiosis

My own Experience

I personally take a 5 billion dosage and am happy to recommend the source offline. However, in addition to obtaining from a reputable provider (i.e. in UK, MHRA approved supplier), there is evidence to suggest as long as it has some or all of the following strains that are widely available, they should provide benefit: Lactobaccilus plantarum, Lactobaccilus acidophilus, Lactobaccilus brevis, Bifidobacterium lactis and Bifidobacterium longum.

This article could have been 10 x longer!  I didn’t even get to the bit about the relationship between the gut and the brain – perhaps another day?

None of this should be considered medical advice.

Article 1 – Vitamin and Mineral Challenges.   This was co-authored by Tara Whyand, UK’s most experienced NET Specialist Dietician.  This blog provides a list of vitamins and minerals which NET Cancer patients are at risk for deficiencies, together with some of the symptoms which might be displayed in a deficiency scenario.

Article 2 – Malabsorption.  Overlapping slightly into Part 1, this covers the main side effects of certain NET surgical procedures and other mainstream treatments. Input from Tara Whyand.

Article 3 – ‘Gut Health’.  This followed on from the first two blogs looking specifically at the issues caused by small intestine bacterial overgrowth (SIBO) as a consequence of cancer treatment. Also discusses probiotics.  Input from Tara Whyand.

Article 4 – Food for Thought.  This is a blog about why certain types of foods or particular foodstuffs can cause issues.

Article 5 – ‘Pancreatic Enzyme Replacement Therapy’. The role of PERT (Creon etc) in helping NET Patients. Input from Tara Whyand.

Read a Gut Surgery Diet Booklet authored by Tara – CLICK HERE

You may also appreciate these articles where there is overlap:

The Diarrhea Jigsaw – different things can cause diarrhea, it’s not all about syndromes.

The Constipated NET Patient – yes they exist!

Very grateful to Tara for the input.

Other useful links which have an association to this blog:

{a} Read a Gut Surgery Diet Booklet authored by Tara – CLICK HERE

{b} Follow Tara on Twitter – CLICK HERE

{c} Watch a video of Tara presenting to a group of NET Patients – CLICK HERE

{d} Now Watch Tara answering the Q&A from patients – I enjoyed this – NET patients are very inquisitive! CLICK HERE

Thanks for listening