Paraneoplastic Syndromes – the NET Effect

Spectrum of paraneoplastic humoral syndromes secondary to NETs. CT, calcitonin; PTHrP, parathyroid hormone related peptide; CGRP, calcitonin gene related peptide; GLP, glucagon like peptide; ANP, atrial natriuretic peptide; VIP, vasointestinal peptide (*). Citation: Endocrine-Related Cancer 17, 3; 10.1677/ERC-10-0024 (* Author's note: not the usual description of VIP indicating a potential ectopic context)

Although several hypotheses have been proposed regarding the pathogenesis of PNSs, the precise mechanism that leads to the development of PNS remains largely unknown. (In simple terms, pathogenesis means “the manner of development of a disease”

Disclaimer. I read widely and noted various papers where there was clearly confusion about the classification of paraneoplastic in relation to Neuroendocrine Neoplasms.  Some papers grouped known Neuroendocrine Tumour hormonal syndromes in, but others were more specific by filtering these into ectopic scenarios.  This is a hugely complex area.  I eventually filtered out papers based on the expertise of the authors and the common threads running in each one.  It was not easy.   

What are Paraneoplastic Syndromes (PNS)?

The term paraneoplastic syndrome (PNS) is used to define a spectrum of symptoms attributed to the production of biologically active substances secreted from tumors not related to their specific organ or tissue of origin and/or production of autoantibodies against tumor cells. (i.e. they are paraneoplastic in an ‘ectopic’ sense).  Worth noting these are not the same as the known hormonal syndromes related to Neuroendocrine Tumours (NETs) but you will see some overlap within the paper used as a reference for most of this research.  You will also note that the original name of the 2010 paper below was entitled Paraneoplastic Endocrine Syndromes.  The word endocrine was removed in the 2020 update.

Important to note:

Although several hypotheses have been proposed regarding the pathogenesis of PNSs, the precise mechanism that leads to the development of PNS remains largely unknown.  PNSs can precede, occur concomitantly or present at a later stage of tumor development and may complicate the patient’s clinical course, response to treatment, and impact overall prognosis. Their detection can facilitate the diagnosis of the underlying neoplasia, monitor response to treatment, detect early recurrences, and correlate with prognosis. When associated with tumors of low malignant potential PNSs usually do not affect long-term outcome. Conversely, in cases of highly malignant tumors, endocrine PNSs can be associated with poorer survival outcomes. 

Clinical awareness and the incorporation into clinical practice of somatostatin receptor based PET scans such as the 68Ga Dotaxxx series, and other evolving biomarkers have substantially contributed to the identification of patients harbouring such syndromes.


It has been estimated that PNSs affect approximately 8-15% of patients suffering from malignant neoplasms, mostly involving the lung, breast, and gastrointestinal system (not just NENs). Clearly a problem bigger than NENs.  However, NENs are the type of tumours expected to exhibit the highest prevalence of PNSs due to their inherent synthetic and secretory capacity.  However, to date the prevalence of NEN-related PNSs is still obscure due the limited availability of data.

Classification of PNSs

According to the clinical manifestations, the NENs-related PNSs may be classified as:

  • Humoral PNSs – in medicine humoral is something relating to the body fluids, especially with regard to immune responses involving antibodies in body fluids as distinct from cells.  There are some overlaps with the NET hormonal syndromes.  See Reference 1 for the complete list of humoral PNSs. 
  • Neurological PNSs – problems affecting the nervous system. These mostly concern non-Neuroendocrine Neoplasms but there is a connection to Small Cell Lung Cancer, technically a type of Lung Neuroendocrine Carcinoma.  See Reference 1 for the neurological PSN list if you have SCLC or another type of Neoplasm.
  • Other less common manifestations. i.e. anything not fitting into humoral or neurological.  See Reference 1.

Resources Used

I first wrote this blog using a paper published in 2010 (the source of the lead diagram and I include it for this purpose below). This was something I found in my research into the term Paraneoplastic Syndromes which has outlined some of these issues in relation to NENs.  In the 2010 version, the authors suggested that paraneoplastic endocrine syndromes are a secondary complication with certain types and certain hormones. Many of these connections are already known, such as Cushing’s syndrome, hypercalcemia, hypoglycaemia. But it can be the knock-on effects of these conditions which can potentially lead to other issues discussed. 

A further variation of the same paper was produced in 2020 contained updated information and Dr Ashley Grossman was again included in the authors list – he is a known expert in NENs and is an Endocrinologist.  I noted the title changed from ‘secondary’ to ‘related’ indicating that thinking may have changed in 10 years.   The other difference I noted was the omission of Endocrine leaving just Paraneoplastic Syndromes as a standalone statement. 

There are many sites talking about Paraneoplastic Syndromes, but most seem to focus on the Neurological PNS sub-classification which is less relevant to NENs.  I did note the National Insitute for Health (NIH) appeared to totally omit the endocrine aspects (humoral) instead focusing on the Neurological PSNs listed above.  Consequently, they omit any connection to NEN Syndromes.  Many other large and well-known US clinics take the same approach. 

The one I will refer to below is more ‘endocrine’ related covering a much wider scope.  It’s also authored by known NET Specialists who are Endocrinologists.

1. Paraneoplastic Syndromes Related to Neuroendocrine Tumors (2020)

Marina Tsoli, MD, PhD, Georgios K. Dimitriadis, Ioannis I. Androulakis, Gregory Kaltsas, M.D., FRCP, and Ashley Grossman, MD, FRCP, FMedSci. Paraneoplastic Syndromes Related to Neuroendocrine Tumors. [Updated 2020 Sep 26]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA):, Inc.; 2000-. Available from:

2. Paraneoplastic syndromes secondary to neuroendocrine tumours (2010)

Kaltsas G, Androulakis II, de Herder WW, Grossman AB. Paraneoplastic syndromes secondary to neuroendocrine tumours. Endocr Relat Cancer. 2010 Jul 28;17(3):R173-93. doi: 10.1677/ERC-10-0024. PMID: 20530594.

The 2020 paper is essentially an update of the 2010 original used as a reference to publish this blog.


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. 

Neither should any post or comment made by a follower or member of my private group be assumed to be medical advice, even if that person is a healthcare professional.   

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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3 thoughts on “Paraneoplastic Syndromes – the NET Effect

  • I stumbled upon this information searching for an answer of why my husband was slurring, confused, falling asleep every five minutes, staring at the floor for 20 minutes, glassy eyed, anxious and memory loss.

    Unfortunately, we moved to a state (respectfully, I will not name which state) no one should live, from Chicago where he had a NETS team. His cancer has metastasized to his liver. Moving here and trying to get treatment has been challenging. Now, with Covid it’s a complete shitshow. He was traveling 500 miles to see his medical oncologist and IR. Although experts in their respective fields of NETs, they are more focused on their research. We just stopped called them, and are moving back to Chicago. We have already been in touch with the NETs team there.

    It’s been difficult to find support where we currently live. After I had to make a two hour trip to a hospital where they do no more than keeping the patients alive so they can be discharged, he told me if he gets demented and starts foaming at the mouth DO NOT take him to a hospital here. Kinda funny, but it’s really not.

    We are hoping to get him to Chicago next week after his case is brought before the tumor board on Tuesday.

    I enjoyed reading your story. Although his condition is very serious, I have hope the docs in Chicago can squeeze a little more life out so he can retire properly and enjoy his hobbies.


  • Theresa

    I’m happy to see this. While my NETS are sleeping, I have had many other issues, aka autoimmune like, and was put on low dose steroids to keep things calm. I spent 3 years post surgery miserable and searching for newest all awhile thinking the NETS were the issue.
    The rheumatologist suggested paraneoplastic syndrome could be a possibility.
    Seems to be a catch all diagnosis however it gives a direction to keep issues under control, at least for me. Currently going down the path of myasthenia Gravis for the 4th time. But I think I just have a super immune system that is keeping the NETs at bay.
    I look forward to reading more. Thanks, Theresa

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