We don't know what causes them. Research is going on to find out more, and we may have some answers in the next few years.

Almost all NETs are isolated cancers and are not inherited, but in a very few cases there may be a family link. For example, carcinoid tumours are more common in people who have a family history of benign (non-cancerous) tumours of the endocrine system.

If there may be such a link in your case, genetic testing and counselling may be available to you and your family.