The initials MEN stand for multiple endocrine neoplasia.

The endocrine organs produce the hormones, the chemicals that control many of our bodies' functions. These organs include, among others, the pituitary gland (which lies immediately underneath the brain), the thyroid gland (in the front of the neck), the parathyroid glands (that lie just behind the thyroid) and the adrenal glands (which sit on top of the kidneys in the abdomen).

The word neoplasia means tumour so multiple endocrine neoplasia is a condition where a number of tumours develop in one or more of the endocrine glands.

In the last 50 years it has been realised that there are two conditions which are caused by faulty genes, and which can be inherited, that lead to multiple tumours developing in several different endocrine organs - so not only does each of the affected glands have several (sometimes many) tumours but also several different glands may be affected. These two conditions have been named multiple endocrine neoplasia I and II (MEN I and MEN II).

MEN I affects about 1 in 10,000 people in the UK and is usually an inherited condition, passed from one generation to the next. Virtually everybody with MEN I develops tumours in their parathyroid glands (these are usually benign, non-cancerous growths). About 7 out of 10 people with MEN I will develop tumours in their pancreas. Depending on the type of cell affected these may be growths called either gastrinomas or insulinomas. These may be either benign or malignant (cancerous) tumours. About one third to one half of people with MEN I will get tumours in their pituitary glands and these are almost always benign growths.

MEN II is also an inherited condition and leads to the development of a type of thyroid gland tumour called a medullary cell carcinoma of the thyroid, This is a cancerous tumour. About half of the people who have MEN II will also develop a type of tumour of their adrenal gland called a phaeochromocytoma. These tumours are usually benign.

MEN II is further divided into two other conditions: MEN IIA and MEN IIB. In MEN IIA people get tumours if their parathyroid glands as well as medullary cell carcinomas of the thyroid and phaeochromocytomas. In MEN IIB people get whitish-yellow or pink swellings on their tongue, lips, eyelids or lining of their mouths (these are called neuromata), as well as the thyroid and adrenal tumours.

Surgery is the mainstay of treatment for MEN, with operations to remove the affected glands. But other treatments may be used as well depending on the specific circumstances of the individual person with the condition.