Neuroendocrine tumours (NETs) develop in the neuroendocrine system. This system consists of nerve and gland cells that make hormones, regulating different organs in the body. The neuroendocrine cells are found in the stomach, lungs, bowels.

The tumours can be either benign (non-malignant) or cancerous (malignant). Most of these tumours glow slowly, even in years, although there are some NETs that can develop fast.

These tumours are also classified by the location where they started; therefore, there can be: small bowel NETs, large bowel, gastric, pancreatic, lung, or in rare cases: gallbladder, bile ducts, kidneys, testicles, ovaries, or the liver.

NETs usually affect people over 60s.



The symptoms of neuroendocrine tumours depend on the location of the primary tumour. The symptoms below are mainly if NETs occur in the stomach, bowels, or lungs. These include:

  • abdominal pain
  • sickness, vomiting
  • chest infections, cough, shortness of breath
  • various symptoms in case of overproduction of a hormone
  • diarrhea
  • weight loss
  • wheezing


NETs in other parts can show the following symptoms:

  • insulinomas (in the pancreas) – high level of insulin, with symptoms like palpitations, anxiety, headaches, confusion, seizures
  • gastrinomas (in the pancreas or small bowel) – high level of gastrin, a hormone that causes production of gastric acid, with symptoms like stomach bleeding, stomach wall perforation, diarrhea, bloatedness, light-coloured and smelly stool, esophagus tightness
  • glucagonomas (in the pancreas) – overproduction of the hormone glucagon that regulates the blood-sugar level; with symptoms like anemia, high blood sugar, blood clots, weight loss
  • VIPomas (in the pancreas) – overproduction of vasoactive intestinal peptide, with symptoms like weakness, tiredness, watery diarrhea, low potassium, sickness, vomiting
  • Somatostatinomas (in the pancreas or the small bowel; very rare type) – overproduction of somatostatin, with symptoms like smelly stool, anemia, diarrhea, weight loss, diabetes

There are also tumours that do not cause any symptoms, known as non-functioning tumours.



The cause of neuroendocrine tumours is unknown. However, some conditions are associated with NETs. Those are:

  • multiple endocrine neoplasia – tumours that develop most commonly in the parathyroid glands, pituitary gland and the pancreas
  • Von Hippel-Lindau syndrome – abnormal growth of blood vessels
  • Neurofibromatosis type 1 – genetic condition where tumours grow along the nerves


Risk Factors

The risks of developing neuroendocrine tumours involve the following factors:

  • Age – usually develops over the age of 60-70
  • Gender – more frequent in men
  • Hereditary causes
  • Immune system suppression due to HIV virus or organ transplant
  • Exposure to arsenic and sun