Episode 87. Neuroendocrine tumours with Professor Rodney Hicks, Dr Michael Lee and Megan Rogers (Part 2)

Neuroendocrine tumours represent neoplasms of the diffuse neuroendocrine system (DNES) which is our body’s largest endocrine organ comprised of the fascinating amine precursor uptake and decarboxylase (APUD) cell series first described in the 1960s by British scientist A.G.E Pearse. These cells can produce numerous peptides and bioactive amines. Influenced by both the endocrine and nervous systems as well as by the chemistry in their local environment, neuroendocrine cells play a vital role in intracellular signalling and ensure the integrated functioning of many organs and systems within the human body working in both paracrine and endocrine fashion. The signalling molecules produced by the diffuse neuroendocrine system represent a universal chemical language, a vital contributor to the regulation of homeostasis. Cells of the DNES are found throughout the body and are present in almost every organ with well-known examples in the lining of the Gi tract, the lungs, pancreas, thymus, thyroid, brain, adrenal glands etc…

Neoplastic transformation results in the development of neuroendocrine tumours (NET’S) most commonly in the small bowel (~60%) followed by the lungs (~27%) and pancreas.

Whilst considered rare more than 5000 diagnoses per year occur in Australia which is more than the combined number of annually reported pancreatic and gastric malignancies. Unfortunately, up to 60% of cases are advanced at the time of diagnosis with metastases and is not uncommon for patients to be misdiagnosed with irritable bowel syndrome. Neuroendocrine tumours may be functional or non-functional (the majority), they may be poorly or well-differentiated, low-grade or high-grade.

NET's have somatostatin receptors (there are 5 known receptors) on the cell surface and up to 80% of NET's express somatostatin receptor 2 which octreotide has a strong attraction for. The gallium dotatate scan exploits this fact by detecting the presence of the somatostatin 2 receptor.

Neuroendocrine cells also contain vesicles stacked with chromogranin which has been utilised as a relatively sensitive and specific marker for NET although elevated levels of this marker may be seen with proton pump inhibitors, renal impairment and atrophic gastritis. 24-hour measurement of urinary 5 hydroxy indole 3 acetic acids (5-HIAA), the degradation product of serotonin, is a useful laboratory marker for NETs producing serotonin.

I was particularly interested to explore this extensive subject further with Professor Rodney Hicks, Dr Michael Lee and Megan Rogers from the Peter MacCallum Cancer Centre all experts in managing neuroendocrine tumours and I was keen to discuss peptide receptor radionucleotide therapy (PRRT) which Professor Hicks whose expertise with this therapy is world renown. Please welcome them to this two-part podcast.

REFERENCES:

petermac.org

neuroendocrine.org.au

www.ncbi.nih.gov (Australian experience of peptide receptor radionuclide therapy in lung neuroendocrine tumours,2020)

www.sciencedirect.com

To be a guest on the show or provide some feedback, I’d love to hear from you: manager@gihealth.com.au Dr Luke Crantock MBBS, FRACP, is a gastroenterologist in practice for over 25 years. He is the founder of The Centre for GI Health, based in Melbourne Australia and is passionate about educating General Practitioners and patients on disease prevention and how to manage and improve their digestive health.