4% of carcinoids are hereditary. The best known of the 2 varieties of inherited carcinoids is associated with the MEN-1 syndrome in which 50% of the family develop the condition which is almost always associated with the presence of other endocrine tumors. These other tumors usually involve the parathyroid glands in the neck and/or the pancreas and core symptoms of their own. There is an obvious strong family history in these cases which can be proved by appropriate blood tests as well as blood chromosomal testing for the MEN gene. This test is expensive but worthwhile in at least the 1 member of such a suspect family who has had proven carcinoid. If that person tests positive it is almost certain that the family has the inheritable condition.
The 2nd type of inherited carcinoid is “familial carcinoid” which can occur without any other endocrine tumors and is more erratic in the percent of family members who will be afflicted. There is no test for a suspected family with carcinoid at the present time. The diagnostician must rely on the family history and careful testing for obscure carcinoid. The entire panel of carcinoid chemical markers should be tested as well as all clinical imaging techniques should be utilized such as OctreoScan, CT scan, upper and lower GI endoscopy, wireless capsule endoscopy, etc. I am participating in studies of familial carcinoid at the NIH which are presently underway.