Neuroendocrine tumours are rare. They start in neuroendocrine cells - these are specialised nerve cells that produce hormones. Neuroendocrine cells are part of the endocrine system, which is a network of glands in the body. The glands produce hormones.

Hormones control many of the body’s functions by controlling the levels of particular chemicals and fluids in the body, and they help us respond to changes in our environment.

Neuroendocrine tumours occur most commonly in the digestive system but can occur in other parts of the body. They can be non-cancerous (benign) or cancerous (malignant).

Some neuroendocrine tumours produce hormones which can cause particular symptoms, such as diarrhoea, flushing of the skin and wheezing. Tumours that produce hormones are called functioning (hormone-secreting). Tumours that don't produce hormones are known as non-functioning (non-hormone secreting).

Cancerbackup has information on the following types of neuroendocrine tumour:

• Carcinoid
• GEPs - Gastroenteropancreatic tumours - which include:
• insulinomas
• gastrinomas
• glucagonomas
• VIPomas
• somatostatinomas