OPINION
– 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. This post was originally generated in April 2015 (and hasn’t changed that much!).
EDIT MARCH 2024. There is now a consolidated Endocrine/Neuroendoceine Tumour classification system (Blue Book). Still in print but you can see a summary of changes by clicking here. This change should provide some leverage to Neuroendocrine committees particularly about what things should be called.
EDIT MARCH 2022. The latest classification system for Lung Neuroendocrine Neoplasms (NEN) confirms the word “carcinoid” is now a choice when you look at the document index. However, the WHO Lung Committee bottled it by leaving it in, and we now need to wait until the next edition due 2026 or so to see if they fall in line with every other ‘blue book’. I made my choice some years ago, I hope others follow suit. Read more about changes to Lung NEN by clicking here.
EDIT APRIL 2020. The latest classification system for Neuroendocrine Neoplasms confirms the word “carcinoid” no longer forms part of the terminology used in Digestive System tumours (effectively removing the term from GEP NETs) – read more – click here
“Carcinoid” – what’s in a name?
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 several of the quotes below:
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).
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 definition. All of this has been reinforced in the 2017 publication. The term ‘Carcinoid‘ is conspicuously missing from these texts and not before time. Ditto on the 2019 output.
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.
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 using quite bizarre terms 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.
As you can see from the quotes above, I’m not alone in this thinking. Many big organisations and NET specialists are phasing out use of the word and NET Specialist organisations have changed their brand names to keep up to date.
Here’s a a recent quote by well known NET expert Dr Eric Liu, who hits the nail right on the head:
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.
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 notoriously out of date 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 until they sort out this mess. Tell them to update as per WHO Classification of Endocrine and Neuroendocrine Tumors 2022.
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. Come on US, reject this legacy misnomer.
One of the issues is that people are not applying the lastest nomenclature published by the World Health Organisation (WHO) classification for Neuroendocrine Neoplasms since 2016. 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) and they move at the speed of a slug in terms of website updates. Easier said than done but ‘change’ always has to start somewhere. Technically it has started (albeit late) as most of 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. I’m happy to fall in line.
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.
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. I could come up with other terms in about 5 minutes. e..g. Lembeck Syndrome (the guy who discovered that carcinoid tumours secreted serotonin)
Personally I don’t see why this cannot be renamed to ‘Neuroendocrine Heart Disease’ or its technical name – ‘Hedinger syndrome‘.
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. Catecholamine crisis associated with Pheochromocytomas and Paragangliomas. The manufacturers of Lutathera have an interesting term documented as “Hormonal Crisis” which also has potential.
Recent developments from US specialists appear to indicate that the treatment for carcinoid crisis (long believed to be octreoide) is wrong and it should be treated as a form of distributive shock. Perhaps the naming will be addressed as this new thinking progresses. Read more aboutr this by clicking here.
However, the naming should be tidied up because ‘carcinoid crisis‘ cannot be applied to ALL types of NET. And as people coninue to remind me, Lung NETs srtill have the ‘carcinoid’ label (see above). My response is then it should only be applied to Lung Carcinoids. I’m intentionally being facetious to make my point!
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