Birth control may be putting women at risk for breast cancer

David Hunter — Nuffield Department of Population Health

It's always been known that hormonal contraception, like any medicine, carries some risks.

Other studies have shown hormonal birth control may lower the risk for ovarian and endometrial cancer.

Results were published Wednesday in the New England Journal of Medicine.

"Hormonal contraception should still be perceived as a safe and effective option for family planning", said Dr. JoAnn Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital, who was not involved in the research.

Unlike most previous research, this study didn't just track the effect of birth control pills.

The study also found that women who stopped using hormonal contraceptives still had a higher risk of breast cancer after five years than women who had never used them.

That may sound scary.

And the importance of allowing women to take control of their fertility and reproduction and decide if, how and when to have a baby can not be overlooked. The illness is fairly rare among women in the age group studied.

"It is a very clear picture for us, very convincing", Mørch said. But they stress there is no need for most women to abandon birth control pills for fear of breast cancer. They also contain progestin, a synthetic form of the female hormone progesterone, which helps regulate the monthly menstrual cycle.

Still, the data show that the search for birth control drugs that don't increase breast cancer risk must continue, he said.

Now, a new study links the use of these birth control methods to an increased risk of breast cancer in women. The risk was higher the longer the contraceptives were used.

Researchers followed more than 1.8 million women for an average of eight years. Epidemiologist Lina Morch headed the study.

About 140 million women use some type of hormonal contraception, including about 16 million in the United States.

NEIGHMOND: Hormonal contraception releases estrogen, progestin or a combination of both to suppress ovulation and prevent pregnancy.

Digging further, the researchers found no differences among types of birth control pills.

MIA GAUDET: Including the patch, the ring, the implant, as well as IUD.

"When we look at all comers, the absolute overall increased risk of breast was one extra case of breast cancer for every 7,690 women using hormonal contraception for one year", said Dr. Rebecca Starck, a gynecologist at the Cleveland Clinic, who was not involved in the study. The findings are disappointing, says epidemiologist David Hunter with the University of Oxford.

Most breast cancers are fueled by estrogen.

"There was a hope that the contemporary preparations would be associated with lower risk", Hunter said. But that's not what this study found.

"Unfortunately this was not the case and additional research is needed to tweak the formulation".

According to the American Cancer Society, one in eight women will be diagnosed with invasive breast cancer in their lifetime.

Morch and Gaudet noted that breast cancer is relatively uncommon in younger women, so a young woman's overall risk of breast cancer still is low, even if she's taking the pill.

MORCH: So it has to be balanced - the pros and cons of these contraceptives.

NEIGHMOND: Now, it's important to note in the study, women over 40 were more likely to suffer breast cancer than younger women in their 20s and 30s.

Keep in mind, oral contraceptives have benefits as well.

"That is a very small extra risk". There's a strong suggestion they actually reduce the risk of colorectal cancer. "That is not a huge risk increase", she told NBC News.



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