Dear Readers
Another week and another discussion about ‘benign vs malignant’ in my group. Let’s put that into context and dispel one big myth.
I write many blogs but one thing I always emphasise is the heterogenous nature of something called Neuroendocrine Neoplasms. That is a ‘catch-all’ term for both well differentiated Neuroendocrine Tumours (NET) and poorly differentiated Neuroendocrine Carcinomas (NEC). Notwithstanding the fact that there is a Grade 3 NET nowadays, the former is often described as ‘slow-growing or ‘indolent’ in behaviour and the latter is almost always faster growing and a more aggressive cancer. NEC is also frequently said to be less common than its less aggressive NET relative but the statistic is reversed if you (quite rightly) include Small Cell Lung Cancer (a Lung NEC) in the data.
I think ‘indolent‘ is a relative word and it’s a word used by my diagnosing Oncologist to describe the relative behaviour of my cancer cells. It is commonly used to describe certain cancers that progress slowly. The issue with NETs is that they very often progress slowly over time without much of a fanfare; and then only discovered when the cancer reaches an advanced stage. Along with many thousands of others, this was my experience and the cancer was clearly not behaving in a benign manner! But tumour indolence doesn’t mean they should not be treated, indolence can also cause morbidity and threaten mortality over time – many people die because of so called ‘indolent’ tumours.
I’ve seen the NET vs NEC statement above described as a ‘dichotomy’ and also highly relevant for prognosis and treatment choice. But the latter is too simple a statement as many well differentiated NETs can sometimes behave aggressively, in some cases like a carcinoma requiring systemic treatment with cytotoxic chemotherapy.
In the main, the indolent tumours tend to follow a prolonged clinical course with a low risk of distant metastases in most types, even in some cases in the absence of treatment. Conversely, the more aggressive carcinomas are associated with a more rapid progression in either small or large cell form.
Well differentiated NETs, particularly at the lower end of the scale tend have a good outlook, even at the higher stages including Stage IV. Some at the lower end of stage and grade can even be removed with curative intent and patients can then be discharged (words from NET specialists and their guidelines). Clearly there are always outliers in any scenario (at each end of the spectrum) but not many people would disagree with either of these statements.
But today I wanted to cover the seemingly endless debate on the term “Benign” in the context of Neuroendocrine Tumours. But before I launch into that, let’s be clear – a NET is a cancer! Read more via the link in the comment.
Benign
This is actually a common word including non-cancer meanings. But in the cancer world, it simply means a tumour that may grow larger but do not spread to other parts of the body, i.e. benign cells don’t typically invade nearby tissue or spread—they’re contained to the tumour. Note, a tumour can be a cancer in the generally accepted definitions used by all healthcare institutes and organisations. So because something has been described as ‘benign’ does not mean it is not a cancer,
However, in the context of NETs, the word is often misused by ignoring malignant potential. I’ve even read anecdotal comments in my patient group that the word was used in Stage IV scenarios, indicating that healthcare professionals are also using it to describe ‘indolent’ (slow-growing) cancers even if they have spread – something which is contrary to any authoritative definition of malignancy or cancerous behaviour you can find online.
Much of the confusion backdates to the invention of the word ‘carcinoid’. However, over 100 years later, it’s become very clear that these tumours, in varying degrees, frequently behave malignantly (not benignly as Oberndorfer mistakenly assumed) with metastasis, local invasion, and recurrence after resection.
I am going to provide quotes from several resources which give you the evidence to push back on anyone who tells you that your Neuroendocrine Tumour is benign.
NETs are malignancies
“NETs are frequently referred to as benign, while they should always be considered malignancies as they do have metastatic potential.”
This quote is from a fairly recent publication in 2023. It only covers Gastroenteropancreatic NETs but that is predominately where the issues are. That said, Lung NETs (and technically Thymus) remain the only anatomical area where the term ‘carcinoid‘ remains in official terminology (clearly the WHO Thoracic committee remain ‘indolent’ on this outstanding matter ……).
The full quote for context is “Another frequently occurring misconception is that NETs are referred to as being benign, as they are generally slow-growing tumors and have a more favorable prognosis even when detected in a late stage. However, since they do have the capability to metastasize, and many patients eventually die of the disease, they should always be considered malignancies.”
“…..Use of the term ‘Carcinoid’ has led to the common misconception that NETs are benign or always indolent”
This quote is also from a fairly recent publication in 2023. I have read many documents by the authors and found that they are not only a highly knowledgeable source of up to date info, but the are also very progressive in what things should be called (we need more of this!). To put the above quote into context “……. The former group was previously termed carcinoid tumors, based on the original observation by Siegfried Obendorfer (1876-1944) in 1907 that NETs of the small bowel displayed “carcinoma-like” or “carcinoid” features. As this term has led to the common misconception that carcinoid (sic) tumors are benign or always indolent, current correct nomenclature of this gastrointestinal malignancy solely uses the term NEN.”
“….we consider all of them cancer”
This one can be found on a well known NET treatment centre in US and has been written by a well known US NET Specialist. Another one which is progressive in approach.
To add context, the quote has been taken from this section “
Are all neuroendocrine tumours cancerous?
The short answer is that neuroendocrine tumours are almost always cancerous. But each situation is unique, so it’s impossible to capture the entire breadth of this disease in a simple yes or no answer.
Some neuroendocrine tumours are only classified as such because of how they appear under a microscope. But from a clinical standpoint, they almost never grow or spread, whether we do anything about them or not. Those cases only account for about 1% of all neuroendocrine tumours. But it’s important to mention them.
In some of the older systems for classifying neuroendocrine tumours, pathologists would describe them as either “benign” (non-cancerous) or “malignant” (cancerous), based on what the tumour cells looked like under a microscope. Unfortunately, those terms did not always accurately reflect whether the tumor would metastasize and behave aggressively or not, so they have been abandoned.
Today, almost all neuroendocrine tumours are considered malignant. There are just differences in how aggressive they are. Some spread easily. Others do not. But we consider all of them cancer”.
Neuroendocrine Tumours (NET) – benign vs malignant
References used
- Relation between WHO Classification and Location- and Functionality-Based Classifications of Neuroendocrine Neoplasms of the Digestive Tract – PMC (nih.gov)
- Gastrointestinal Neuroendocrine Tumors and the Carcinoid Syndrome – Endotext – NCBI Bookshelf (nih.gov)
- What are neuroendocrine tumors, and how are they treated? | MD Anderson Cancer Center
Disclaimer
I am not a doctor or any form of medical professional, practitioner or counsellor. None of the information on my website, or linked to my website(s), or conveyed by me on any social media or presentation, should be interpreted as medical advice given or advised by me.
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Please also note that mention of a clinical service, trial/study or therapy does not constitute an endorsement of that service, trial/study or therapy by Ronny Allan, the information is provided for education and awareness purposes and/or related to Ronny Allan’s own patient experience. This element of the disclaimer includes any complementary medicine, non-prescription over the counter drugs and supplements such as vitamins and minerals.
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