One of the key awareness messages for Neuroendocrine Cancer is the hormonal syndromes that can often accompany the diagnosis for many people.  As it’s a difficult disease to diagnose, many people struggle with these syndromes for some time before formal diagnosis of Neuroendocrine Cancer.  Some continue to struggle after.

Neuroendocrine Cancer can often be uncannily quiet, but the tumours can be ‘functional’ and over-secrete certain hormones to add or introduce symptoms that mimic many other diseases or conditions, such as Irritable Bowel Syndrome, Menopause, Heart disease and Asthma.   In addition to common symptoms of flushing and diarrhea, others include generally feeling weak, fatigued, pain, agitated, anxious, dizzy, nauseous, acid reflux, skin irritation, anaemic, weight loss, weight gain, low blood sugar, high blood sugar, heart palpitations, headaches, sweating, high blood pressure. Its main trick is to prevent you from being correctly diagnosed and it’s pretty good at it.  For those looking for a diagnosis, it can be very frightening.

One or more of the NET syndromes can be a weird concoction of strange, powerful or terrifying ingredients, designed to make you very ill; and doctors will be confused.

(So called) Carcinoid Syndrome

Certain types of Neuroendocrine Cancer were once referred to by the archaic misnomer ‘Carcinoid‘ – now correctly referred to as a NET prefixed by its anatomical primary location. However, for the time being, the term Carcinoid Syndrome which can be associated with some of these types of NET persists. The classic carcinoid syndrome includes flushing (80%), diarrhea (70%), abdominal pain (40%), valvular heart disease (20% since the introduction of somatostatin analogues), telangiectasia (25%), wheezing (15%), and pellagra-like skin lesions (5%).  Carcinoid Syndrome is one of the most powerful and dangerous ‘witches brews’. 

Carcinoid syndrome, first described in 1954 by Thorson and co-workers, has the following features: malignant neuroendocrine tumour of the small intestine, normally with metastases to the liver, sometimes with valvular disease of the right side of the heart (pulmonary stenosis and tricuspid insufficiency without septal defects), peripheral vasomotor symptoms, bronchial constriction, and an unusual type of cyanosis. One year later, Dr. William Bean gave the following colourful description of carcinoid syndrome:

“This witch’s brew of unlikely signs and symptoms, intriguing to the most fastidious connoisseur of clinical esoterica—the skin underwent rapid and extreme changes resembling in clinical miniature the fecal phantasmagoria of the aurora borealis.” 

Certain Neuroendocrine Tumours are known to be capable of over secreting (amongst others) the vasoactive substance called serotonin – mainly midgut (carcinoid syndrome in hindgut and foregut is rare and atypical when it presents). It’s commonly thought that serotonin is the cause of the flushing, but this is only partially correct, the flushing also results from secretion of kallikrein, the enzyme that catalyses a conversion to bradykinin, one of the most powerful vasodilators known. Worth pointing out that flushing can be caused by other NET hormonal syndromes.

A very common component of carcinoid syndrome (and other syndromes) is diarrhea, probably caused by the increased serotonin, which greatly increases peristalsis, leaving less time for fluid absorption.  In the extreme, this syndrome can cause a pellagra-like condition, probably due to the diversion of large amounts of tryptophan from synthesis of the vitamin B3 (Niacin), which is needed for NAD production (oxidized form of B3).

Serotonin is also thought to cause fibrotic lesions of the endocardium (Hedinger Syndrome), particularly on the right side of the heart resulting in insufficiency of the tricuspid valve and, less frequently, the pulmonary valve and, uncommonly, bronchoconstriction. Other fibrosis issues arising from excess secretion of serotonin include mesenteric and retroperitoneal desmoplasia which have the potential to dangerously obstruct important vessels and cause general discomfort at best.