Mucinous colon carcinoma in a black family.

Carcinoma of the large bowel developed in an autosomal dominant pattern in 13 members of a black-American family. Seven members were affected prior to initial ascertainment of the family in 1976. Thereafter, the remaining six were affected while 0.2 cases were expected (p less than 0.001). Median age at diagnosis of colon cancer was 39 years (range, 22-62 years) in this family, compared with 65 years among black-Americans, in general. Histologic review of surgical specimens from six patients and medical record data for a seventh patient showed mucinous adenocarcinoma of the colon, an uncommon histologic variant. Studies of several family members a decade ago had revealed no biologic markers of cancer susceptibility.