[Oral contraceptives and breast cancer--a causal relationship?].

Concern about the relationship between oral contraceptives, which have been used by more than 200 million women, and the risk of breast cancer has been present since three decades. Early studies showed no consistent results, but some authors are concerned about several subgroups having possibly an increased risk of developing breast cancer. A meta-analysis representing 90% of the data available on the topic showed a small but significant increase in the relative risk of developing breast cancer in women currently using oral contraception (1.24). This risk decreases after oral contraceptives have been ceased (1.16-1.07) and is comparable after 10 years to that of controls.