Familial gastrointestinal carcinoid tumours and associated cancers.

BACKGROUND Carcinoid tumours are neuroendocrine neoplasms mainly located in the gastrointestinal tract and bronchopulmonary system. Our study's aim was to characterise the familial nature of gastrointestinal carcinoid tumours using the Swedish Family-Cancer Database, which includes >11.5 million individuals. METHODS Familial relative risks (RRs) of carcinoid tumours were estimated for individuals with family history of invasive cancers. RRs of invasive cancers for the offspring of patients with carcinoid tumours were calculated as well. RRs were based on Poisson regression. RESULTS The risk of carcinoid tumours was significantly increased among individuals with a parental history of carcinoid tumours (RR 4.33). An association was also found between carcinoid tumours in the offspring and parental invasive cancers of the brain, breast, liver, endocrine glands and urinary organs. In addition, parental invasive cancers of the kidney as well as squamous cell skin cancer associated with small intestinal carcinoids in the offspring. The risk of carcinoid tumours was elevated among those whose siblings were affected by colon and rectal cancers. CONCLUSION The results describe the familial aggregation of carcinoid tumours with other noncarcinoid malignancies. Carcinoid tumours are rare and translating these results into screening programmes needs more research; however, gene finding studies should be stimulated.