[P-pills and risk of breast cancer. A review of studies published 1970-1990].

A review of five cohort and 33 case-control studies provides evidence of an increased risk of breast cancer in women aged less than 45 years who were exposed to oral contraceptives for 5-10 years. It is probable that the increased risk is related to oral contraceptive use before the first pregnancy. No association was found between oral contraceptive use and breast cancer risk in women aged 45 years or more.