Since its foray onto the market, hormonal contraception options have been surrounded by a somewhat-gray area of risk. Doctors and women alike have hoped that newer, low-dose contraceptive pills, IUDs and implants lowered the risk of breast cancer (some studies even touted the idea these eliminated the risk entirely) when compared to their higher-dose counterparts, but a new Danish study—it’s been dubbed the largest study of its kind—says even lower-dose methods elevate the risk for breast cancer.
The research published in the New England Journal of Medicine on Wednesday was based around a study of 1.8 million women between the ages of 15 and 49. Over the course of 11 years, researchers aimed to understand what would occur to these women who used hormonal birth control (often a combined estrogen and progestin, but also tested the patch, the ring, implants and IUDs) versus women who relied on non-hormonal contraceptives (condoms, diaphragm or copper IUDs).
You May Also Like: Which Birth Control Gives You Better Skin, And Which Makes It Worse
The results are startling. Women who stayed on hormone-releasing contraceptives for 10 or more years experienced a 38-percent increase in their risk of developing breast cancer, compared with nonusers. By contrast, there was no increased risk for breast cancer seen in women who used hormones for less than one year. Even more, the new study estimated that for every 100,000 women, hormone contraceptive use causes an additional 13 breast cancer cases a year, meaning that for every 100,000 women using hormonal birth control, there are 68 cases of breast cancer annually, compared with 55 cases a year among non-users.
Because the research tracked the long-term effects of multiple types of contraceptives, as well, the study was able to determine whether modern options (like IUDs and the patch) are “safer” than the pill. The answer: it didn’t matter which hormonal method was used. Lina Morch, a research epidemiologist at the University of Copenhagen, who led the study, says the team found “a roughly 20 percent increased risk [of breast cancer] among women who currently use some type of hormonal contraceptive.” The longer the women used hormonal methods, the higher their risk.
While many doctors and users have assumed a lower dose of hormones meant a lower risk of cancer, the truth is that the same elevated risk is present in either dose. In an editorial commentary accompanying the new study, David J. Hunter, a professor of epidemiology and medicine at the University of Oxford, explains the new study did not find any modern contraceptives were risk-free. “There was a hope that the contemporary preparations would be associated with lower risk,” he said in an interview. “This is the first study with substantial data to show that’s not the case.”
For now, we’re hopeful that new contraceptive methods (ones that don’t elevate this risk at all) will surface. Until then, a conversation with your doctor about the best options for you is a great place to start.