Breast cancer and oral contraceptives: a review

The relationship between oral contraceptive use and breast cancer was investigated in 22 major epidemiological studies, which are reviewed in this paper. The overall risk ratio was never found to increase when computed among all users vs. nonusers. Risk increases were found in some studies within specific subgroups; but in general, if any risk exists, it is not much more than one. Future studies should focus specifically on women under age 25, on women before a first full-term pregnancy and, to a lesser extent, on perimenopausal women and on women who have had a benign breast disease.