Neuroendocrine Cancer – not as rare as you think


Although initially considered rare tumours up until 10 years ago, the most recent data indicates the incidence of NETs has increased exponentially over the last 4 decades and they are as common as Myeloma, Testicular Cancer, and Hodgkin’s Lymphoma. In terms of prevalence, NETs represent the second most common gastrointestinal malignancy after colorectal cancer. Consequently, many experts are now claiming NETs are not rare (see below).  A recent study published on 5 Dec 2018 reports that even if you isolate Small Intestine NETs in the USA population, the incident rate is 9/100,000. Contrast this against the US incident rate as at 2012 of 7/100,000 for all NETs.  The rare threshold in Europe is 5/100,000 and below.

And on 7th January 2019, an internationally known NET Specialist described NETs as very common.

strosberg not rare
In fact, the graph of the SEER database figures for NETs in both 2004 and 2012 indicates the rate of incidence increase is faster than any other cancer on the planet, particularly attributed to lung, small intestine, and rectal NETs.  The World Health Organisation’s revised classification of Neuroendocrine Neoplasms in 2010, abandoned the division between benign and malignant NET as all NETs have malignant potential and should be graded accordingly.  The 2004 SEER data compiled did not take into account what might have been considered to be benign NETs.

However, the most recent USA study up to 2012 has confirmed the incidence beyond 2004 has continued to rise (and rise, and rise, and rise) and this is covered below in the section entitled “Meanwhile in USA”. One of the principal authors of both database studies has now gone public and said NETs are no longer rare. 

Incidence and Prevalence

Before I continue, it’s important to understand the difference between incidence and prevalence.  In the crudest of terms, incidence is the number of new cases of a disease being diagnosed (normally aligned to a specific quota of the population per year, generally 100,000). Prevalence normally indicates an amount of people living at any one time with a disease. It’s also important to note that different nations or groups of nations classify ‘rare’ in different ways – not really helpful when looking at worldwide statistics.

So why the increase?  I suspect the reasons include (but are not limited to), more awareness (population and medical staff), better detection techniques and probably more accurate reporting systems, at least in USA, Norway, Canada and now in the UK i.e. a mixture of underdiagnoses and misreporting.  The Canadian study is important as it also noted the proportion of metastases at presentation decreased from 29% to 13%. This is the first study that suggests an increased incidence of NETs may be due to an increased (and earlier?) detection. This has the knock on effect of increasing prevalence as most NET Cancer patients will normally live for longer periods.  Add to this the plethora of better treatments available today, you have a highly prevalent cancer. Most of that is good news.

However, their true incidence may be higher owing to the lack of diagnosis until after death.  For example, in USA, a respected NET specialist stated that the autopsy find for (excuse the outdated terminology) ‘carcinoid‘ is 4 times the recorded diagnosis rate. In Australia, one study claimed that 0.05% of all autopsies found a Pheochromocytoma or Paraganglioma.  A very interesting slideshow from a well respected NET expert claimed there are 200,000 undiagnosed NET patients in USA. Slide below:  You may also wish to check out my article “The Invisible NET Patient Population” where this is explored further.


US SEER 2004 – The Trigger and Turning Point

In the largest study of its kind up to that point, well-known Neuroendocrine Cancer expert James C. Yao researched the Surveillance, Epidemiology and End Results (SEER) database. His team studied 35,825 cases of Neuroendocrine Cancers in the United States covering data between 1973 and 2004. The report concluded that in 2004 there were 5.25 new cases of NETs per 100,000 people, compared with 1.09 per 100,000 in 1973 [1]. This is in contrast to the overall incidence of malignancies, which has remained relatively constant since 1992 (see the yellow line on the graph). The study also pointed out that due to increased survival durations over time, NETs are more prevalent than previously reported. If you analyse the NET data for 1994 (10 years before the end of the study period), you will see an incidence rate of approx 3.25/100,000. In 2004, the incidence rate had risen to 5.25/100,000. Although not an exact science, it does suggest the potential incidence rate at 2014 (10 years after the study period) might possibly have climbed well beyond 6/100,000 and even further if the same rate of increase displayed by the study had continued (spoiler alert – it actually came out as 7/100,000 see below under ‘Meanwhile in USA’). This study also confirmed a prevalence of 103,000 NET patients as at 2004. As this is regarded as the most accurate NET statistic ever produced, it is interesting to note that was at a time when the prognostics for NET were not as good as they are today indicating there must be a very significant increase if extrapolated to the current time. Moreover, this was prior to the WHO 2010 reclassification of NETs so more diagnoses will be counted today that were not counted in 2004. See below to see the significance of this figure (see section ‘Do the math’).

The 2004 data was an astonishing set of statistics – particularly as they were based on 12 year old data. However, there is now new data up to 2012 that overtakes the above-mentioned groundbreaking study and confirmed the incidence is now even higher.  See section entitled “Meanwhile in USA …….” 

SEER study 2004 – NETs

Meanwhile in Norway ……

Data from the Norwegian Registry of Cancer showed a similar incidence of Neuroendocrine Cancers with a 72% increase between 2000 and 2004 compared with 1993–1997 [2]. Also in Norway, an article published in 2015 entitled “Epidemiology and classification of gastroenteropancreatic neuroendocrine neoplasms using current coding criteria” indicated a high crude incidence of GEP-NEN, at 5·83 per 100 000 inhabitants over the period 2003-2013 (adjusting to 7.64 for Europe in 2013 – see diagram below extracted from cited article 2a).  It was also noted together with the statement “….a significant increasing trend over time”. [2a] Citation [2b]
extrapolation europe

Meanwhile in Canada …….

CNETs have highlighted an article published in the magazine ‘Cancer’, February 15, 2015, showing that the incidence of Neuroendocrine Tumours has markedly increased in Canada over the course of 15 years (1994-2009). The results showed that the incidence of Neuroendocrine Tumours has increased from 2.48 to 5.86 per 100,000 per year. [3] [4]

simron singh nets not rare

Meanwhile in UK …….

The latest figures from Public Health England (PHE) indicate the incidence of NETs has risen to almost 9/100,000 (i.e. not rare) using the latest International Classification of Diseases for Oncology (ICD-O) methodology version 3 – ICD-O-3. Even that figure is understated because it does not include Lung Neuroendocrine Carcinomas (i.e. SCLC and LCNEC). As at 31 Mar 2016, the age-standardised incidence rate for NETs in England (excluding small and large cell neuroendocrine carcinomas, SCLC and LCNEC respectively) was 8.84, 8.37 in males and 9.30 in females – rising from 3.9 in 2001.  These figures are from the NET Patient Foundation and were issued as a result of a NPF and PHE (NCRAS) partnership project which has been compiling statistics on the incidence, prevalence and survival of NET Patients in England using English cancer registry data. They also have an aim to also access the rest of UK cancer registry data to get UK wide figures.

That means a new NET diagnosis every 2 hours. You can see a summary of the report   NEW:  Public Health England release new incidence data for Neuroendocrine Cancer

A slide from the recent UKINETS 2017 conference indicating an agreement from UK and Ireland NET Specialists.

as presented at UKINETS 2017

Meanwhile in New Zealand …….

as presented by Unicorn Foundation NZ on 11 Mar 2017

Meanwhile in USA …….

The latest evidence of its rise is contained in the largest ever study ever conducted. It is based on data up to 2012 so it’s worth noting that this data is now 5 years old (3 years for the project prevalence figure), so even these figures may still be conservative.  The document, which was published in 2017 can be found here: Click here.  A short summary follows:

In this population-based study that included 64 971 patients with neuroendocrine tumors, age-adjusted incidence rates increased 6.4-fold between 1973 and 2012, mostly for early stage tumors.  Survival for all neuroendocrine tumors has improved, especially for distant stage gastrointestinal and pancreatic neuroendocrine tumors.

Of the 64 971 cases of NETs, 34 233 (52.7%) were women. The age-adjusted incidence rate increased 6.4-fold from 1973 (1.09 per 100 000) to 2012 (6.98 per 100 000). This increase occurred across all sites, stages, and grades. In the SEER 18 registry grouping (2000-2012), the highest incidence rates were 1.49 per 100 000 in the lung, 3.56 per 100 000 in gastroenteropancreatic sites, and 0.84 per 100 000 in NETs with an unknown primary site. The estimated 20-year limited-duration prevalence of NETs in the United States on January 1, 2014, was 171 321

Conclusion: The incidence and prevalence of NETs have continued to rise in the United States, owing to the increased diagnosis of early-stage disease and possibly stage migration. The survival of patients with NETs has improved, and this improvement has been greater for those with distant gastrointestinal NETs and, in particular, distant pancreatic NETs.

Combine that with a revised annual incidence rate of 23,000 and the very well known fact that NETs is a highly prevalent disease, it must be mathematically impossible for the figure not to be above the USA rare threshold of 200,000 in 2017.  As you can see from the graph below, the incidence rate for NETs continues to outstrip the incidence rate for all malignant neoplasms (another word for tumour).  Amazingly, the report authors even state “…….. it is likely that we have underestimated their true incidence and prevalence”.

not rare yao netrf

incidence 2012 jama
NET Cancer diagnoses continues to outstrip all other cancer diagnoses

The NET Research Foundation published an amazing infographic which summarises the output of the SEER 2012 study (although it does omit the prevalence figure ‘as at’ date).  See it below and you can read the accompanying text here.

Graphic from the NET Research Foundation –

Let’s do the Math

Neuroendocrine Cancer is not only the fastest growing cancer in incidence terms but as a group of cancers, given the mounting epidemiological evidence, it can no longer be rare as a grouping of cancers.  Neuroendocrine disease IS NOT RARE.

For example, if you roughly extrapolate the US SEER data graph above to 2017 and recalculate the prevalence rate based on 23 000 per year from the 2014 figure of 171 321.  Unfortunately, some people will have passed, but it’s well documented as a highly prevalent cancer and therefore more people live. The prevalence of neuroendocrine tumors in USA was higher than the combined estimated prevalence of esophageal cancer (n = 36,857), gastric adenocarcinoma (n = 79,843) and pancreatic adenocarcinoma (n = 49,620) in 2013. In fact, one of the conclusions of the 2012 SEER report is that we are living longer with NETs. This is in line with many other cancers due to improved diagnostic and treatment regimes.  Cleary more work still needs doing.

Dr Kunz has done the math
hendifar not rare
Dr Hendifar has done the math
not rare yao netrf
Dr Yao has done the math

simron singh nets not rare
Dr Singh has done the math

strosberg not rare
Dr Strosberg has done the math

The Invisible NET Patient Population

The heading of this section is my name for those who have not yet been diagnosed with NETs but are walking around having been either misdiagnosed, diagnosed with another cancer in the same part of the anatomy, living and putting up with the symptoms whilst the tumours grow.  To add to this part of the underdiagnoses of NETs is this most amazing piece of research published in 2018 – Pan-cancer molecular classes transcending tumor lineage across 32 cancer types, multiple data platforms, and over 10,000 cases.  It was published in the American Association of Cancer Research (AACR) journal ‘Clinical Cancer Research and authored by Chad Creighton et al. D.  This was a pan cancer piece of research which indicated that Neuroendocrine disease may be more prevalent than anyone had ever thought.  There’s a summary article here which I suggest you read fully.  The rather explosive extract is as follows:

We expected that about 1 percent of

Go figure

Whilst reporting has been improved, it is most likely still not 100% accurate. Therefore, even the figures above may be understated due to an incorrect cause of death reporting and incorrect diagnosis/recording of the wrong cancers (e.g. pNETs recorded as Pancreatic Cancer, Lung NETs recorded as Lung Cancer, etc).  This is certainly still happening in UK and I suspect in most other countries. Add to that the regular reports of Neuroendocrine Tumours being found during autopsies and you have the potential for an even further unrecorded increase had these been found prior to death. In fact, according to SEER 2012, the true incidence and prevalence is most likely underestimated. In fact here is a statement straight from the horse’s mouth:

SEER 2012 Underestimated
more math

The issue is also complicated by the method used in USA for naming a disease ‘rare’. Rather than use incidence rates, the USA uses the number of people living with the disease at any one time (i.e. essentially the prevalence). This is currently 200,000 as a threshold – anything below that is considered rare.  It seems mathematically impossible for NETs to be less than 200,000 given the data provided above.

Eric Liu Not Rare

When I first started researching NETs back in 2010, the US figure (which varies from source to source) was around 125-150,000.  Why are people quoting figures less than this in 2017 when the 2014 figure has now been confirmed above? There also seems to be a selective omission of the new US incidence rate of 7/100,000.

You will also see that Dana Farber is estimating more than 200,000 people are as yet undiagnosed.  Even if that were 50% accurate, it would put the current prevalence figure in US over 300,000.

Let’s cut to the chase – NETs are not rare, they are just less common

Are we shouting loud enough about this?  I don’t think so.  ‘Rare’ is very frequently used within the NET community almost to the point of being a status symbol. Based on these figures, this looks like an outdated approach along with its associated icons.  The evidence above is so compelling that saying the group of cancers officially called Neuroendocrine Neoplasms is rare is starting to sound like fake news.

“A neoplasm on the rise.  More prevalent than you may think.  Incidence increased dramatically during past 3 decades” (Novartis)

“it’s less rare than we used to think. It’s more malignant than we previously thought” (Dr Richard Warner)

“… is one of the most rapidly increasing cancers in the U.S. There has been a 500-percent increase in the last 30 years” (Dr Edward Wolin)

“Estimated more than 200,000 undiagnosed cases in the US” (Dana Farber)

“I actually think NETs are not a rare cancer” (Dr James Yao)

“NETS will no longer be rare” (UKINETS 2017 one of the opening slides)

“NETs are no longer rare” (Dr Andrew Hendifar)

“…..when you think of prevalence, NETs are actually quite common” (Dr Jonathan Strosberg)

“One study showed that the number of people diagnosed has risen 50% over the last decade and unfortunately, I worry that is an underestimate” (Dr Eric Liu)

“Neuroendocrine Cancer – NETs are not rare, just less common.  We need a new paradigm” (Ronny Allan since 2015)

You may also wish to check out my article “The Invisible NET Patient Population” where this is explored further.

Carcinoid vs Neuroendocrine


CARCINOID misnomer etc

There’s a constant debate regarding the validity of the term ‘Carcinoid‘.  I’ve posted about this a few times and as far as I know, the debate has been raging for some years.

You may have noticed that ‘Carcinoid’ is often used as a standalone word and tends not to be suffixed with the word ‘Cancer’ or ‘Tumour’ – unlike Bowel Cancer, Breast Cancer, Prostrate Cancer, Lung Cancer, Brain Tumour, etc.  Nobody goes around saying “Breast” or “Bowel” do they?  But they happily say “Carcinoid”.  Unfortunately, the term ‘Carcinoid’ has become entrenched in both pathology and clinical literature over the past 100 years. The main problem with the word Carcinoid is that it means different things to different people. Some use the term almost exclusively to designate serotonin-producing tumours that arise from the enterochromaffin cells that can result in carcinoid syndrome i.e. most commonly in the appendix, small intestine, stomach, lung, rectum and uncommonly in other places. Some use it to (incorrectly) refer to all Neuroendocrine Tumours. The most worrying connotation of the use of the word ‘Carcinoid’ is the belief that they all have benign clinical and biological behaviour.  That is dangerous thinking and has the potential to kill people.  Fortunately, NET specialists are starting to move away from using the word – check out the quote below:
carcinoid falling out of favor

Siegfried Oberndorfer
Siegfried Oberndorfer

The Origins

The following history of ‘Carcinoid’ is well documented: Siegfried Oberndorfer (1876-1944) became the first to adequately characterise the nature of Carcinoid tumours and refer to them as “benign carcinomas.” During his tenure at the Pathological Institute of the University of Munich, Oberndorfer noted in 1907 that the lesions were distinct clinical entities and named them “karzinoide” (“carcinoma-like“), emphasizing in particular their benign features. However, In 1929 he amended his classification to include the possibility that these small tumours could be malignant and also metastasise. (Author’s note – a name change would have been handy at this point).

100 years later

NANETS, UKINETS and ENETS seem to defer to the WHO classification nomenclature and it is here another term is introduced – Neuroendocrine Neoplasms (NENs).  NANETs state that “all of the entities under discussion are neoplastic, and neoplasm is therefore a more accurate term than tumor, which means only a mass“.  These organisations tend to use the term Neoplasm as a catch-all for all Neuroendocrine disease and then the term ‘tumor’ and ‘carcinoma’ applies to well and poorly differentiated respectively.  It’s worth noting that since 2010, the WHO classification is based on the concept that all NETs have malignant potential, and has therefore abandoned the division into benign and malignant NETs and tumours of uncertain malignant potential. Neuroendocrine Carcinoma is malignant by defintion. All of this has been reinforced in the 2017 publication. The term ‘Carcinoid’ is conspicuously missing from these texts.

To put it simply – the term ‘carcinoid’ is no longer credible

Due to its historical meaning, Carcinoid does not adequately convey the potential for malignant behaviour that accompanies many of these neoplasms as described above.  The term Carcinoid decodes to ‘Carcinoma like’.  Contextually “Carcinoid Cancer” decodes to “carcinoma like cancer” which is, of course, totally misleading and its use simply perpetuates the claim by some that it is ‘not a proper cancer’.  If we only needed one reason to ditch the word ‘Carcinoid’, this would be it.

carcinoid is inadequate oberg quote 2016

I mentioned confusion above and this has led to a hybrid effect of naming the condition.  For example, there is a tendency by some (including medical establishments and patient organisations) to use the term ‘Carcinoid’ and ‘Neuroendocrine Tumors’ interchangeably which is patently incorrect. Neither is it helpful that many patients and organisations continue to refer to this disease as “Carcinoid Neuroendocrine Tumor”, “Neuroendocrine Carcinoid Tumor”, “Neuroendocrine Carcinoid Cancer”, “Carcinoid/Neuroendocrine”, “CNET”; and many other variations along these lines. Many seemingly credible organisations will say “Carcinoid and Neuroendocrine Tumors” not realising it’s a contradiction in terms. Continued use of the term in any phrase or standalone context is not doing our case for recognition any good – it’s bad enough that some seem to cling to outdated and invalid diagnostic clichés and icons from the 1980s.  All of it needs to go.

carcinoid npf quote

I know I’m not alone in this thinking given the decrease of its use in the NET world, including NET Specialists (see lead graphic) and NET Specialist organisations (some have changed their names).  There’s an interesting article written by a NET specialist where the term ‘carcinoid’ is described as “unfortunate”, “misleading”, “outmoded”, “archaic”, “confusing” and “misnomer”. Exactly!  In the recent SEER NET study, a NET specialist reaffirmed this thinking by stating that “the belief these tumors did not metastasize, did not reach any great size, and appeared harmless, has since been proven false”.  Continued use of the term ‘Carcinoid’ has the potential to regress this thinking.  We must not let this happen.

referring to carcinoid

So what terms should we be using?

People and organisations will be out of date with modern Neuroendocrine Neoplasms nomenclature and some will still want to continue with their own nomenclature (….. and because of the confusion, some will fall into both categories not realising they’re out of date).  Here’s a classic example of the problem we face – the American Cancer Society(ACS) does not even list Neuroendocrine Tumor as a cancer type.  Instead you can find “Gastrointestinal Carcinoid Tumors” and “Lung Carcinoid Tumor”. You’ll find Pancreatic NETs inside Pancreatic Cancer.  Americans should harangue the ACS to get this right. I could go on with many similar observations on seemingly respectable sites. I intentionally used a US example as this country appears to be way behind in the changes to NET nomenclature, pretty surprising as they tend to be at the forefront of many other aspects in the world of NETs.

Personally, I think the acceptance of a common worldwide nomenclature should come from the World Health Organisation (WHO) classification for Neuroendocrine Neoplasms.  They are divided into a number of chapters including ‘Endocrine Organs’, Digestive System, Lung Tumours….. and no doubt some others.  Frustrating, but medical people tend to look at things in anatomical terms. Nonetheless, the agreed classification nomenclature for the whole group of Neuroendocrine Neoplasms can be found with some research and access to clinical publications.  The correct nomenclature should then be flowed down in regional groupings, e.g. ENETS representing Europe, NANETS representing North America, etc.  As I understand it, ENETS and UKINETS are already essentially aligned with WHO and NANETS appears to be. From these organisations, the use of the correct terminology should then rub off on patients, patient advocate organisations and general cancer sites.  However, the biggest challenge will be with hospitals/medical centres, cancer registries and insurance companies whose medical record processing is run using reference data (think drop down selections and database structures).  Easier said than done but ‘change’ always has to start somewhere.  Technically it has started (albeit late) as the big NET medical organisations are already starting to reduce the use of outmoded words such as ‘carcinoid’.

I once argued that the term ‘carcinoid’ needed to be retained as it represented a histopathological grouping of a particular type of NET comprising mostly appendiceal, stomach (gastric), rectal, small intestine and lung NETs.  However, reading through the ENETS 2016 guidance in conjunction with the most up to date WHO classification publications, I’ve changed my mind after noticing they no longer use the word ‘Carcinoid’ in relation to a tumor type.  Rather, they use the latest WHO terms above and then use the anatomy to distinguish the different types of NET (like we already do for Pancreatic NET or pNET).

Perhaps patients can lead the way here ………

Rather than say:

‘Carcinoid’ or ‘Carcinoid Tumor’….. why not say Neuroendocrine Tumor or NET (adding your primary location if required – see below);

‘Carcinoid Cancer; ….. why not say Neuroendocrine Cancer;

‘Lung Carcinoid’ ….. why not say Lung NET (adding typical or atypical if required);

‘Small intestine Carcinoid’, why not say Small Intestine NET (or ‘SiNET which is becoming popular); p.s. I’m not a fan of ‘small bowel’ due to the potential for confusion with the widely used term ‘bowel cancer’);

‘Gastric Carcinoid’, why not say Gastric NET (adding your type if required);

‘Rectal Carcinoid’, why not say Rectal NET;

‘Appendiceal Carcinoid’, why not say Appendiceal NET;

…. and so on.  And you can add your stage and grade/differentiation for a richer picture.

You can listen to a very well known NET Specialist say something similar in this video here.

Worth noting that even ENETS and NANETS cannot agree on tumor type terminology – the latter uses Small Bowel NETs (SBNETs) whereas ENETS uses Small Intestine NENs (SiNENs). I did say it’s easier said than done.

As I said above, the term ‘Carcinoid’ has become entrenched in both pathology and clinical literature over the past 100 years so it will still appear in many texts and need to be searchable online to support medical and advocacy business.  However, these are technical issues and I don’t therefore believe people need to use the terms to make them searchable online.  I tag all my posts with ‘Carcinoid’ even if I don’t mention the word in my text.  I have started only using the term for context when it is required and am currently reviewing all of my posts to ensure that is still the case.

Hang on…what about Carcinoid Syndrome

When someone wants to know which syndrome you have, you can’t just state (say) “small intestine syndrome” or “midgut syndrome”.  ‘NET Syndrome’ doesn’t work either as there are several NET syndromes.  This has led to the situation where people try to drop the word ‘carcinoid’ and just say “the syndrome” which is even more confusing! I accept this one is a difficult challenge but I don’t believe it’s insurmountable, just needs some willpower and agreement.

What about Carcinoid Heart Disease

Personally I don’t see why this cannot be renamed to ‘Neuroendocrine Heart Disease’ or its technical name – ‘Hedinger syndrome’.

What about Carcinoid Crisis

World renowned NET specialists already make statements that these issues can apply to all types of NET; and it’s well-known that a similar crisis situation already applies to other types e.g. Pheochromocytomas.  I cannot see why something along the lines of ‘Neuroendocrine Crisis’ or ‘NET Crisis’ would not be acceptable.


We as patients are unlikely to be able to force changes on the medical and insurance communities but we can be a ‘force for change’ by setting the example of using a correct and more apt terminology to describe our disease.


Thanks for listening


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