Abstract
The 'cancer family syndrome', which is characterized by an excess of colon and endometrial cancer lacks any reliable laboratory or clinical marker. Variable age of onset further confounds the demonstration of simple inheritance in this syndrome. We have studied 15 families which manifest the syndrome and report statistical and genetic analyses on 5 of the larger families. In a typical family, we have examined relative cancer risk among: (1) offspring of parents in the direct genetic line who have been affected with colin and/or endometrial cancer; (2) offspring of unaffected parents in the direct genetic line; and (3) unrelated spouses. Cumulative cancer risk (colon and/or endometrium) to members of these informative groups in the 20 to 59 year age span was found to be (1) 58%, (2) 0%, and (3) 7%, respectively, which constitutes an excess risk of 51% to offspring of affected parents compared with unrelated spouses. This estimate, the vertical transmission, and lack of sex predilection to cancer are supportive of a simple mode of inheritance. Families of this type, through identification of high cancer risk individuals, provide important implications for improvement of cancer control.