A case-control study of use of postmenopausal female hormone supplements in relation to the risk of large bowel cancer

Postmenopausal female hormone use has been associated with a reduced risk o f colon cancer. We assessed the relation of use of these supplements to the risk of large bowel cancer. The data were collected in a case-control stud y of large bon el cancer conducted in Massachusetts. Control subjects were matched to incident cases of carcinoma of the colon or rectum on age, gende r, and town precinct. The analysis was restricted to women who experienced a natural menopause or had had a hysterectomy with or without removal of th e ovaries (292 colon cancer cases and 112 rectal cancer cases and their mat ched controls). Use of female hormone supplements was associated with a dec reased risk of colon cancer among recent users (odds ratio, 0.6; 95% confid ence interval, 0.4-1.0) and long duration (5+ years) of use (odds ratio, 0. 5; 95% confidence interval, 0.3-0.9). The association with long duration of use appeared to be independent of recency of use and screening practices a nd was apparent for late-stage cancer. Hormone supplement use was not assoc iated with a reduced risk of rectal cancer. Our results add to the evidence for a decreased risk of colon cancer associated with use of female hormone supplements.