Familial occurrence of carcinoid tumors and association with other malignant neoplasms.

Carcinoid tumors are generally thought to be sporadic, except for a small proportion that occur as a part of multiple endocrine neoplasia syndromes. Data regarding the familial occurrence of carcinoid as well as its potential association with other neoplasms are limited. A chart review was conducted on patients indexed for malignant carcinoid tumor of the gastrointestinal tract seen at the Mayo Clinic between 1988 and 1996. A survey of family history of malignancies and personal history of other tumors was mailed to all eligible patients. Data for 245 patients were analyzed. Observed rates of carcinoids and other malignancies were compared with Surveillance, Epidemiology, and End Results data. Estimates of the cumulative probability for first-degree relatives developing a carcinoid tumor were calculated. Nine (3.7%) patients with carcinoid tumor had at least one first-degree relative with the same malignancy. The rate of carcinoid tumor in first-degree relatives of probands was higher (P < 0.0001) than expected based on the Surveillance, Epidemiology, and End Results population data. Cumulative probability in a first-degree relative for developing a carcinoid was calculated to be 1.5% at age 80. There was an increased risk for developing a carcinoid tumor among first-degree relatives of patients with carcinoid. Neither patients with carcinoid nor their first-degree relatives had an increased incidence of other malignancies.