A one-month pack of hormonal birth control pills. Photo: Rich Pedroncelli / AP
Women who use hormonal birth control — pills or devices that release hormones — are at a slightly higher risk for breast cancer, per a new study published in the New England Journal of Medicine.
Why it matters: It "upends widely held assumptions about modern contraceptives for younger generations of women," who think hormonal contraceptives are safer than old methods that contained higher amounts of estrogen, the New York Times reports.
The numbers: Scientists studied 1.8 million Danish women for over a decade and found those who used hormonal contraceptives had about a 20% increased risk of developing breast cancer. Among women who used hormonal birth control for more than 10 years, the risk rose to 38%. The study estimates 55 cases of breast cancer among every 100,000 women who do not use hormonal contraceptives and 68 cases among every 100,000 who do.
The bottom line: The study showed a relatively small increased risk for cancer among women who used these forms of contraceptives. Still, “there was a hope that the contemporary preparations would be associated with lower risk ... This is the first study with substantial data to show that’s not the case," David J. Hunter, a professor of epidemiology and medicine at the University of Oxford, told the NYT.