Investigation of the possible relationship between oral contraceptives and benign and malignant breast disease

In a case-control study in progress at five London teaching hospitals, 220 women aged 16–39 years with lumps in the breast (54 malignant and 166 benign), together with 216 matched controls, were interviewed between December 1, 1968 and December 31, 1970. No evidence has been found so far that oral contraceptives are associated with an increased risk of breast neoplasia; indeed these preliminary data suggest that the preparations tend to protect against the development of benign lesions.