I found some of the quotes from the recent NET SEER Database study (Dasari et al) very interesting. The National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program is a comprehensive source of population-based information initiated in 1973 that is updated annually. Although the study is US-based, it represents the largest study of Neuroendocrine Tumors (NETs) ever recorded and is therefore a good guide to what might be found beyond USA. In fact, other national declarations of incidence and prevalence of NETs seem to bear these statistics out, i.e incidence rates of 7-8/100,000 …… almost 7 times the rate recorded in the 1970s. If you want to understand the factors behind this massive increase, I covered this extensively in my post “Neuroendocrine Tumors – not as rare as you think“. In this article, I looked at USA and beyond. Those who are regular readers of my articles will already know I’ve been ‘banging on’ about this for a few years. Other organisations and individuals (including NET specialists) are now indicating these tumors are not rare, some vindication for my aforementioned ‘banging on’. This is now a serious disease with some serious statistics behind it and we need a new way of doing things.
There are two further quotes which I’d like to focus on in this article:
1. From the NET SEER Database study published 2017:
” …… many cases of NETs may not have been reported to cancer registries unless considered malignant…… it is likely that we have underestimated their true incidence and prevalence” – i.e. the slide here:
2. From Dana Farber (Kulke, Chan):
“Estimated more than 200,000 undiagnosed cases in the US” – this slide here:
…. But what do these quotes actually mean? Here’s my take:
Underestimating the true incidence and prevalence of NETs
I studied the latest SEER NET study, formally titled “Trends in the Incidence, Prevalence, and Survival Outcomes in Patients With Neuroendocrine Tumors in the United States” (authored by Arvind Dasari, MD, MS; Chan Shen, PhD; Daniel Halperin, MD; et al). From this document, I can see the authors were aware of the well-known faults in cancer registries worldwide and the effect this has on the true incidence and prevalence of Neuroendocrine Cancer. These issues, which are a worldwide problem, include the incorrect registration of Neuroendocrine Cancer as other types based on the anatomical location of the primary tumor. At this point, you may wish to check out my post “The Human Anatomy of Neuroendocrine Cancer” which provides some real life examples of the confusion between primary Neuroendocrine location and other cancers. That said, things are definitely improving because the latest SEER data shows a marked increase in the incidence of High Grade Neuroendocrine Carcinomas (NEC), an area where this issue is prevalent. A similar increase in NEC was also illustrated in the UK’s figures from Public Health England (PHE) in 2016 (click here) indicating that cancer registries are getting better and not before time, although it has to be said this only came about due to a major intervention by NET Patient Foundation and others. Through this work, it’s becoming clear that the incidence of all NETs in UK is around 8 to 9 per 100.000 (rare threshold <=5).
But there’s another issue impacting whether a diagnosis is actually entered on a cancer registry or not. Unfortunately, there are members of the medical community who still see well differentiated NETs as benign tumors, ‘not a proper cancer’ and looking at the nomenclature being used, some of them are still living in last century (‘Carcinoid World’). You can occasionally be excused for being out of date but being 8 years (plus) out of date is unacceptable. The WHO 2010 classification for NETs was based on the concept that all NETs have malignant potential. Here’s a quote from the UKINETS Guidelines in 2011 (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 WHO 2017 for Endocrine Organs reinforces this statement.
The undiagnosed NET patient population
From above, you can see why the incidence (and therefore the prevalence) of our disease has almost definitely been underestimated. However, that’s not the end of my story……..
A number of statements are clear about Neuroendocrine Tumors:
- Low/Intermediate grade well differentiated tumors are known to have been growing slowly over a number of years before discovery or accurate diagnosis occurs,
- They can be difficult to diagnose,
- They are not that well-known amongst the general medical population,
- Many people are initially misdiagnosed with another condition, with some this will result in late presentation with metastatic disease.
- Many NETs are found during autopsies.
The living undiagnosed. It’s worth pointing out that one of the conclusions made by the recent SEER NET study is that the increase in incidence and prevalence can be attributed to a number of factors including earlier diagnosis. This is of course excellent news. Also worth noting that another conclusion of the study is that we are all living longer, reflecting improvements in therapies. This is also great news and is a factor in increased prevalence figures. However, it seems obvious that there are hundred of thousands of people out there still be diagnosed who have tumors silently growing inside them and who are in a loop of referrals between first and secondary care awaiting a proper diagnosis. See the Dana Farber slide above.
The dead undiagnosed. 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 (based on the known incidence rate at the time, this is 8 per 100,000). In Australia, one study claimed that 0.05% of all autopsies found a Pheochromocytoma or Paraganglioma. A Hong Kong study indicated that 1% of all autopsies discovered an ‘Islet Cell’ tumour (i.e. a Pancreatic NET or pNET). It’s possible that many of these had no symptoms but it’s equally possible that many of these people had symptoms but just put up with it and/or had been diagnosed with something else and then died without a correct diagnosis.
The potential undiagnosed. To add to the underdiagnoses of NETs issue, 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 has ever thought. There’s a summary article here which I suggest you read fully. The rather explosive extract is as follows:
I suspect there’s an invisible patient population for many conditions but the slow-growing and relatively quiet nature of Neuroendocrine Cancer means there could be a significant undiagnosed burden walking around, looking for a diagnosis, putting up with symptoms and being treated for other conditions. I see people on forums looking for clues, social media can sometimes be helpful here. That said, I do get the feeling some do not have NETs, regardless of the symptoms they associate with the disease, but I guess many of them will go on to be formally diagnosed with something. I’m contacted by many ‘undiagnosed’ people on my own blog and supporting Facebook sites (mostly privately) and I can tell you that’s a tough gig. I only hope I’ve given them some useful ideas about where to look or what to ask/suggest.
I feel earlier diagnosis reported in the SEER study is partly due to increased awareness, particularly in the medical world. I would also suggest that it has improved in the general population to the explosion of social media information dissemination. It’s also accurate to say that improvements in diagnostic capabilities is also playing its part in pushing up incidence rates, just as improved therapies have pushed up prevalence rates, something emphasised by Dasari (et al) in the most recent study.
The issues caused by inefficient registries together with ‘the undiagnosed’, combine to suggest there is a large invisible NET patient population out there ……. we just need to find them!
Thanks to NET Patient Foundation for featuring this article here.
Thanks for reading