Oral contraceptive use and histopathology of cancerous breasts in young women. Members of the U.K. National Case-Control Study Group.

A retrospective histopathological study of 300 women under 36 years of age was carried out to determine whether breast cancers occurring in oral contraceptive users showed any differences in pathological features compared with non-users. The patients belong to an age group in which an increased risk of cancer development has been reported following oral contraceptive usage. The incidence of non-neoplastic conditions in the residual breast was also studied in the two groups. There was little difference between breast cancers arising in pill users and non-users but in the residual non-neoplastic breast a decreased incidence of cysts and blunt duct adenosis was found in current users of the contraceptive pill. In contrast, lactational foci were found only in the breasts of pill users. The incidence of intraductal hyperplasia was not significantly different in the two groups.