One of the most controversial aspects of Neuroendocrine Tumours (NETs) is the ‘benign vs malignant’ question. It’s been widely debated and it frequently patrols the various patient forums and other social media platforms. It raises emotions and it triggers many responses ….. at least from those willing to engage in the conversation. At best, this issue can cause confusion, at worst, it might contradict what new patients have been told by their physicians (….or not been told). This post will not cover Neuroendocrine Carcinoma which by definition is malignant.
Any definition of the word ‘tumour’ will confirm it can either be benign or malignant. However, and while I’m sure there are benign NETs, the key statement to explain any slow growing or indolent NET is that they all have malignant potential – thus why surveillance and follow up is really important. This is the key factor in the changes found in the 2010 Digestive System World Health Organisation (WHO) classification system from the previous ‘flaky’ version. This reinforcement of the malignant potential of all NETs was duplicated in the recent 2017 Endocrine System equivalent, which is now proposed as a classification scheme for all NETs (see below).
Of course we are not helped by the continued use of the term Carcinoid which decodes to ‘Cancer Like’ – that is potentially regressing the work of those specialists who are trying to undo the last 100 years of complacency in the medical world (and not really the type of awareness we need). The word is gradually being erased from NET nomenclature and the recent 2018 proposal by the International Agency for Research on Cancer (IARC) and WHO NET expert consensus panel to ditch it from the remaining versions of out of date WHO classifications (e.g. Pulmonary/Lung, Pituitary, Head & Neck, Genito-urinary, Adrenal and Paraganglia, Skin), is the final nail in the coffin for Carcinoid. RIP Carcinoid. This also supports our awareness issues with the media reporting the wrong cancer types based on anatomy of the primary tumour. Dear Doctors, Patient Advocates and Patients ….. please stop using the word!
I have lost count of the stories from Neuroendocrine Cancer patients who have been told their tumour was benign but then returned with incurable and metastatic cancer sometime downstream. Clearly there are doctors who do not understand NETs and/or are not aware of the changes in WHO classification schemes since 2010. Sure, some will prove to be ‘benign’ in nature and may not cause many issues but any Ki-67 below 3% is a formal grade of Neuroendocrine Neoplasm. I accept that it’s currently difficult to work out which cases will turn more aggressive and when, thus why surveillance and follow up are really important and also why patients should be seeing doctors who understand NETs. Worth also noting that many slow growing and indolent tumors can still often produce troublesome NET syndromes.
I’ve even heard one patient story where it was claimed a doctor called a metastatic NET case benign! Any definition of ‘benign’ on any respectable cancer site, will include the statement that they do not spread to other parts of the body. The NET Patient world is full of slow growing Grade 1 Stage 4 patients – by definition, they’re all malignant.
Read more detail in these articles as these issues are inextricably linked.
I’m sure there are scenarios in all cancers where tumours can be benign and will never harm the person but if a Doctor says you have a Neuroendocrine Tumour and not to worry because it’s benign, ask questions. Start with “how do you know it will never turn malignant” and “what will be done going forward to check”.
Thanks for listening
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One of the most controversial aspects of Neuroendocrine Tumours (NETs) is the ‘benign vs malignant’ question. It’s been widely debated and it frequently patrols the various patient forums and other social media platforms. It raises emotions and it triggers many responses ….. at least from those willing to engage in the conversation. At best, this issue can cause confusion, at worst, it might contradict what new patients have been told by their physicians (….or not been told). I don’t believe it’s an exact science and can be challenging for a NET specialist let alone a doctor who is not familiar with the disease.
NANETS Guidance talks about the ‘…heterogeneous clinical presentations and varying degrees of aggressiveness‘ and ‘…there are many aspects to the treatment of neuroendocrine tumours that remain unclear and controversial‘. I’m sure the ‘benign vs malignant’ issue plays a part in these statements.
In another example, ENETS Guidance discusses (e.g.) Small Intestine Tumours (Si-NETs) stating that they ‘derive from serotonin-producing enterochromaffin cells. The biology of these tumors is different from other NENs of the digestive tract, characterized by a low proliferation rate [the vast majority are grade 1 (G1) and G2], they are often indolent’. However, they then go on to say that ‘Si-NETs are often discovered at an advanced disease stage – regional disease (36%) and distant metastasis (48%) are present‘. It follows that the term ‘indolent‘ does not mean they are not dangerous and can be ignored and written off as ‘benign’. This presents a huge challenge to physicians when deciding whether to cut or not to cut.
To fully understand this issue, I studied some basic (but very widely accepted) definitions of cancer. I also need to bring the ‘C’ word into the equation (Carcinoid), because the history of these tumours is frequently where a lot of the confusion lies. The use of the out of date term ‘Carcinoid’ exacerbates the issue given that it decodes to ‘carcinoma like‘ which infers it is not a proper cancer. See more below.
Let’s look at these definitions provided by the National Cancer Institute. Please note I could have selected a number of organisations but in general, they all tend to agree with these definitions give or take a few words. These definitions help with understanding as there can be an associated ‘tumour’ vs ‘cancer’ debate too.
Cancer – Cancer is the name given to a collection of related diseases. In all types of cancer, some of the body’s cells begin to divide without stopping and spread into surrounding tissues. There are more than 100 types of cancer which are usually named for the organs or tissues where the cancers form. However, they also may be described by the type of cell that formed them.
Author’s note: The last sentence is important for Neuroendocrine Tumour awareness (i.e. Neuroendocrine Tumour of the Pancreas rather than Pancreatic Cancer).
Carcinoma – Carcinomas are the most common grouping of cancer types. They are formed by epithelial cells, which are the cells that cover the inside and outside surfaces of the body. There are many types of epithelial cells, which often have a column-like shape when viewed under a microscope.
Author’s note: By definition, Carcinomas are malignant, i.e. they are cancers. High Grade (Grade 3) poorly differentiated “NETs” are deemed to be a ‘Carcinoma’ according to the most recent World Health Organisation (WHO) classification of Neuroendocrine Tumours (2017) and ENETS 2016 Guidance. You will have heard of some of the types of Carcinoma such as ‘Adenocarcinoma’ (incidentally, the term ‘Adeno’ simply means ‘gland’). It follows that Grade 3 Neuroendocrine Carcinomas are beyond the scope of this discussion.
Malignant – Cancerous. Malignant cells can invade and destroy nearby tissue and spread to other parts of the body.
Benign – Not cancerous. Benign tumors may grow larger but do not spread to other parts of the body.
Author’s Note: This is a key definition because there are people out there who think that low grade NETs are not cancer.
Tumour (Tumor) – An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called Neoplasm.
Author’s Note: Neoplasm is an interesting term as this is what is frequently used by ENETS and NANETS in their technical documentation, sometimes to cover all Neuroendocrine types of cancer (Tumor and Carcinoma). It follows that a malignant tumour is Cancer. The term “Malignant Neuroendocrine Tumour” is the same as saying “Neuroendocrine Cancer”
Neuroendocrine Tumours – Benign or Malignant?
Definitions out of the way, I have studied the ENETS, UKINETS and NANETS guidance both of which are based on internationally recognised classification schemes (i.e. the World Health Organisation (WHO)).
In older versions of the WHO classification schemes (1980 and 2000), the words ‘benign’ and ‘uncertain behaviour’ were used for Grades 1 and 2. However, the 2010 edition, the classification is fundamentally different (as is the recent 2017 publication). Firstly, it separated out grade and stage for the first time (stage would now be covered by internationally accepted staging systems such as TNM – Tumour, (Lymph) Nodes, Metastasis). Additionally, and this is key to the benign vs malignant discussion, the WHO 2010 classification is based on the concept that all NETs have malignant potential. Here’s a quote from the UKINETS 2011 Guidelines (Ramage, Caplin, Meyer, Grossman, et al).
Tumours should be classified according to the WHO 2010 classification (Bosman FT, Carneiro F, Hruban RH, et al. WHO Classification of Tumours of the Digestive System. Lyon: IARC, 2010). This classification is fundamentally different from the WHO 2000 classification scheme, as it no longer combines stage related information with the two-tiered system of well and poorly differentiated NETs. The WHO 2010 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.
The guidance in 2017 WHO reinforces this statement to include endocrine organs, including the pancreas and adrenal glands.
History lesson – Carcinoid tumours were first identified as a specific, distinct type of growth in the mid-1800’s, and the name “karzinoide” was first applied in 1907 by German pathlogist Siegfried Oberndorfer in Europe in an attempt to designate these tumors as midway between carcinomas (cancers) and adenomas (benign tumors).
The word ‘Carcinoid’ originates from the term ‘Carcinoma-like’. ‘CARCIN’ is a truncation of Carcinoma. ‘OID’ is a suffix used in medical parlance meaning ‘resembling’ or ‘like’. This is why many people think that Carcinoid is not a proper cancer.
The situation is made even more confusing by those who use the term “Carcinoid and Neuroendocrine Tumors” inferring that it is a separate disease from the widely accepted and correct term ‘Neuroendocrine Tumor’ or Neuroendocrine Neoplasm. A separate discussion on this subject can be found in this post here. I encourage you to stop using the term ‘Carcinoid’ which is just perpetuating the problem.
How are NETs Classified?
If you read any NET support website it will normally begin by stating that Neuroendocrine Tumours constitute a heterogeneous group of tumours. This means they are a wide-ranging group of different types of tumours. However, the latest WHO classification scheme uses the terms ‘Neuroendocrine Tumour’ for well differentiated Grade 1 (low-grade), Grade 2 (Intermediate Grade) and Grade 3 (High Grade) NET; and ‘Neuroendocrine Carcinoma’ for Grade 3 (High Grade) poorly differentiated tumours. They also use the term ‘Neoplasm’ to encompass all types of NET and NEC. So Grade 1 is a low-grade malignancy and so on (i.e any grade of NET is a malignant tumour). You may benefit from reading my blog article on Staging and Grading of NETs as this is also a poorly understood area.
Can some Tumours be Benign?
By any accepted definition of cancer terms, a tumour can be non-cancerous (benign) or cancerous (malignant). This is correct for any cancer type. For example, the word is used in the 2016 version of Inter Science Institute publication on Neuroendocrine Tumors, a document I frequently reference in my blog. For example, I’ve seen statements such as “These tumors are most commonly benign (90%)” in relation to Insulinoma (a type of Pancreatic NET or pNET). Ditto for Pheochromocytoma (an adrenal gland NET). Adrenal and Pituitary ‘adenomas’ are by definition benign (adenoma is the benign version of Adenocarcinoma). And I note that there is a ‘benign’ code option for every single NET listed in the WHO International Classification of Diseases (ICD) system.
The ‘BUT’ is this – all WHO classification systems are based on the concept that all NETs have malignant potential. The WHO 2017 classification update confirmed this thinking by adding endocrine organs including the pancreas and adrenal glands.
Can Tumours be Malignant or become Malignant?
Using the definition above, if a tumour invades and destroy nearby tissue and spread to other parts of the body, then it’s malignant (i.e Cancer). However, there’s a reason why the WHO declared in 2010 that all NETs have malignant potential (as amplified in WHO 2017). It may not happen or it may happen slowly over time but as Dr Richard Warner says, “they don’t all fulfill their malignant potential, but they all have that possible outcome”. Thus why ongoing surveillance is important after any diagnosis of Neuroendocrine Tumour of any grade or at any stage. Dr Lowell Anthony, a NET Specialist from the University of Kentucky explains this much better than I can – CLICK HEREto hear his two-minute video clip.
This was a difficult piece of research. I do believe there are scenarios where NETs will be benign and probably never cause the person any real harm (e.g. many are found on autopsies). I suspect this is the same for many cancers. However, based on the above text and the stories of people who have presented for a second time but with metastatic disease, use of the word ‘benign’ is probably best used with great care.
I would certainly (at least) raise an eyebrow if someone said to anyone with any NET tumour, “you don’t need any treatment or surveillance for a NET”; or “it has been cured and no further treatment or surveillance is required”. Particularly if they are not a NET specialist or a recognised NET Centre.
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:
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.
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.
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.
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 videohere.
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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