A carcinoid tumour is a rare type of tumour that usually grows really slowly. It is possible to live with these tumours for many years without knowing that you have them. These tumours are most often diagnosed in people between 55-65 years old. Fewer than 10% of people with carcinoid tumours have or develop symptoms. Carcinoid tumours can grow anywhere in your body where hormone-producing cells are present. Experts don’t know what causes these tumours. If you have a rare disease that runs in families called multiple endocrine neoplasia type 1 (MEN1) or if you smoke, you have a higher risk of developing a carcinoid tumour1.