Study links new birth control methods to slight increase in breast cancer risk

Rich Pedroncelli/AP

• Contraceptives containing hormones have long been associated with an increased risk of breast cancer.
• A study has found that new hormonal contraception options (like low-hormone pills, IUDs, and vaginal rings) come with a similar level of risk. 
• Experts say the overall breast cancer risk is still very low.

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Contraceptives containing the hormones estrogen and progestin have long been associated with an increased risk of breast cancer.

Now, a study published Wednesday in the New England Journal of Medicine suggests that newer options in hormonal contraception — lower-estrogen and progestin-only pills, intrauterine devices (IUDs), vaginal rings, implants, and more — still carry a similar level of increased risk.

Given the variety of birth control methods and different formulations of hormonal contraception now available, Lina Mørch, Ph.D, senior researcher with Copenhagen University Hospital and the new study's lead author, had hoped to see a lower risk of breast cancer than previous research had suggested. But it's "very comparable with what we saw before,'" she says.

How concerned should women be who are using hormonal methods of birth control? Experts say that both this new study and most prior research—which was done on contraceptives with higher levels of hormones—suggest that the overall breast cancer risk is still very low.

"It's not something which you should be sleepless about," says Øjvind Lidegaard, D.M.Sci., professor of obstetrics and gynecology at Copenhagen University Hospital, a co-author of the new study.

Here's what you need to know about the latest finding, and the link between birth control and breast cancer.

Birth control and breast cancer risks

Both previous research and this study, which followed about 1.8 million Danish women for an average of 11 years, found that those using hormonal contraception have about a 20 percent higher risk of developing breast cancer than others.

Twenty percent may sound like a big jump in risk, but the overall risk is still minimal, say the study authors. For example, the risk to the women studied—who were between 15 and 49—translated into just one additional diagnosed case of breast cancer per year for roughly every 7,690 women using hormonal contraception.

As with older research, the new study also found that the breast cancer risk rose the longer you used the contraceptive: Less than a year of hormonal birth control therapy led to only a 9 percent increased risk of breast cancer, while more than 10 years led to a 38 percent increased risk.

In addition, the new study found—like previous research—that the heightened risk of breast cancer diminishes once you stop using hormonal contraception.

Although the current research evaluated birth control and breast cancer risk in Danish women, according to Mia Gaudet, Ph.D., a breast cancer epidemiologist with the American Cancer Society (who wasn't involved with the study), the results are relevant for U.S. women, because products available here are similar to those used in Denmark.

"This isn't an alarm-bell-worthy finding, but does provide important information for women to consider when they're deciding on the best contraceptive method for them," Gaudet says.

Bizuayehu Tesfaye/AP

What should you do?

The finding that all forms of hormonal birth control and breast cancer risk are linked may have most relevance for women as they grow closer to menopause, Gaudet says.

That's because your overall risk of breast cancer rises with age (most breast cancers are diagnosed after age 50). Taking birth control boosts that risk further, albeit slightly.

But hormonal birth control has benefits, too. Not only can it help alleviate menstrual pain and irregularity and treat acne, studies show that it is associated with a reduced risk of endometrial and ovarian cancers.

When making your decision, Mørch at Copenhagen University Hospital recommends that you discuss the risks and benefits of hormonal birth control with your doctor in the context of your overall health history.

Hormonal contraception isn't for everyone: Women who have already had an "estrogen-related" cancer, are 35 or older and smoke, have a history of blood clots, or have liver disease or certain other conditions, shouldn't use a combination estrogen-progestin pill, for example.

If you're not a candidate for hormonal birth control, or prefer not to use it, hormone-free options are available, including the non-hormonal intrauterine device and barrier methods, such as condoms. The Center for Disease Control and Prevention offers a guide to the effectiveness of various kind of birth control here.

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