Cystic disease, family history of breast cancer, and use of oral contraceptives.

Epidemiologic studies show a lower frequency of fibrocystic breast disease among users of oral contraceptives than among women who have never used them. Family history of breast cancer appears to be more common among benign breast disease patients than among their controls. To determine the use of oral contraceptives and the presence of family history of breast cancer, information was obtained from 211 cystic cases and their matched controls from the metropolitan Toronto area. Cystic cases compared to controls had a higher proportion of women with a family history of breast cancer (21% vs 15%). For both a positive and negative family history of breast cancer, as well as for all women combined, the mean duration of oral contraceptive use was lower for cystic cases than for controls. The odds ratio for oral contraceptive use according to family history of breast cancer for cystic cases and controls was 0.42 and 0.81 respectively. The possibility that a woman is more protected against benign breast disease by using oral contraceptives if she has a family history of breast cancer deserves more attention in future investigations on the long-term effects of birth control pills.