Carcinoid tumours are one member of a family of tumours called neuroendocrine tumours which develop from neuroendocrine cells. Neuroendocrine cells are cells which show some of the features of nerve tissue and some of the features of glandular tissue.

Carcinoid tumours can occur in various parts of the body. They are most often found in the appendix. Other sites where they occur are the small intestine, the lower part of the large bowel (the rectum) and the airways the leading into the lung (the bronchi).

Carcinoid tumours may be benign or malignant (cancerous). The majority of carcinoid tumours are benign. Malignant carcinoid tumours are quite rare with less than a thousand new cases each year in the United Kingdom.

Carcinoid tumours in the appendix are almost always small and benign. They are usually discovered as chance findings when someone has their appendix removed because of appendicitis. Once they have been removed no further treatment is needed.

For carcinoid tumours occurring at other sites in the body it is often difficult to be sure whether they are benign or malignant. Even malignant carcinoid tumours are often very slow growing and may cause little in the way of symptoms for some years.

The cornerstone of treatment for these tumours is surgery. When the tumours are benign and are completely removed the cure rates are excellent. Those that are malignant (cancerous) may still do well. Those that are slow growing may benefit from a partial removal of the tumour which may help to prolong life and it is not uncommon for people to live for years despite having cancer remaining after surgery.