Oral contraceptives and benign breast disease

In 1980 a questionnaire was mailed to 726 nurses who had previously entered a study of breast disease in the late 1940s and 1950s; 665 responded. Between the ages of 30 to 49 years, 137 reported detecting their first signs of benign breast disease and 76 reported receiving their first biopsy for these signs. Long-term oral contraceptive usage reduced the risk of developing signs of benign breast disease and the risk of biopsy for these signs. The potential bias due to the effect of prior benign breast disease on the prescribing practices for oral contraceptives was minimized by considering oral contraceptive usage prior to detecting the first signs of benign breast disease.