[Hormonal contraception and breast cancer risk]

The largest meta-analysis comprised a total of 54 epidemiologic studies (Collaborative Group on Hormonal Factors in Breast Cancer) and included 53,297 women with breast cancer and 100,239 controls. Women currently using hormonal contraceptives had a modestly elevated risk for breast cancer (RR 1.24). This risk continuously decreased over years and did not exist after discontinuation of the drugs after ten years. Women who had started on contraceptives before the age of 20, had an elevated risk for breast cancer over the subsequent years (relative risk = RR 1.95 until the 30th year of age, RR 1.54 between 30 and 34 years, and RR 1.27 between the age of 35 and 40 years, respectively) compared to those who started to use contraceptives after 20 years of age. There was no difference in the risk between the different dosages, combined or gestagen-based contraceptives. However, the proportion of women using gestagens only was small. Study data on the effect of oral contraceptives in women with BRCA1/2 mutation or women with a positive familial history are controversial. A recently published systematic overview of 10 studies including a pooled analysis of 54 studies did not reveal an elevated breast cancer risk for women carrying an elevated breast cancer risk taking contraceptives.