Another study bemoans hormones.

A large prospective cohort study from Denmark is making waves for reporting a 20% relative increase in breast cancer incidence among women who use hormonal contraception. But this news isn’t really news since there have been multiple prior studies that have established this association. The major takeaway is, yes, there is (still) an increased risk of breast cancer with hormonal contraception, though the absolute risk is small and is tempered with the reduced risks of ovarian and endometrial cancers. But this study also offers a couple of unique contributions: 1) subjects who mostly took “modern” forms of contraception including current formulations of oral contraceptives and hormone releasing IUDs and 2) a huge (1.8 million) population on whom they could perform important subset analyses. Of note, there appears to be a dose-response relationship such that risks are greatest (and most prolonged after discontinuation) in women who use contraceptives for longer. Which is important to put in the context of their other alarming finding of no risk-free forms of hormone-based contraception. Finally, the excess risk appears to become more significant as women get older--likely resulting from both longer exposure and increased baseline incidence. In short, hormonal contraception comes at a cost, and it price discriminates based on age and duration of use.