(Reuters Health) - Women who currently use or recently used hormone-based contraception face a 20 percent higher risk of breast cancer, although the overall risk for most women is relatively low, a new study of 1.8 million women in Denmark has concluded.
Older contraceptives were known to carry a higher risk of breast cancer, but doctors had hoped that the newer lower-estrogen formulations might pose a lower risk.
The new findings, reported in The New England Journal of Medicine, show that they do not, and the longer the products were used, the greater the danger.
The researchers calculated that hormone contraception produced one extra case of breast cancer for every 7,690 women each year. That’s a lot of cancers, given that 140 million use hormonal contraception worldwide – or about 13 percent of women ages 15 to 49.
Breast cancer strikes about 255,000 U.S. women each year and kills about 41,000, according to the American Cancer Society.
The study shows that “the search for an oral contraceptive that does not elevate the risk of breast cancer needs to continue,” said Dr. David Hunter of the University of Oxford in a Journal editorial.
Beyond the fact that they provide an effective means of contraception and may benefit women with menstrual cramping or abnormal menstrual bleeding, “the use of oral contraceptives is associated with substantial reductions in the risks of ovarian, endometrial, and colorectal cancers later in life. Indeed, some calculations have suggested that the net effect of the use of oral contraceptives for 5 years or longer is a slight reduction in the total risk of cancer,” Hunter said.
But as women get into their 40s, non-hormonal alternatives such as IUDs might be better, he said. Most cases of breast cancer were seen in women using oral contraceptives in their 40s.
“I don’t think anyone’s going to say stop taking oral contraceptives. That’s not necessary and not supported by the data,” said Dr. Roshni Rao, chief of breast surgery at New York - Presbyterian/Columbia University Medical Center in New York City, who was not involved with the study. “But it does show an increased risk, so for people who don’t have a great reason for taking oral contraceptives, or are amenable to alternatives, perhaps they should think about it.”
Such alternatives include a copper IUD, condoms or, if women are done having children, tubal ligation.
The new study looked at all women in Denmark ages 15 to 49 who had not had cancer, clots in their veins, or treatment for infertility. The women were followed for nearly 11 years.
The 20 percent increase in breast cancer risk varied by age and how long the women used hormone-based contraceptives, including pills, contraceptive patches, vaginal rings, progestin-only implants, and injections.
The risk was 9 percent higher with less than one year of use and 38 percent higher with more than 10 years of use.
“Another thing that has not been clear before is that after discontinuation, if you have used this product for more than 5 years, the risk seems to be increased, even after 5 years of discontinuation of the drugs,” chief author Dr. Lina Morch, a senior researcher at Copenhagen University Hospital told Reuters Health by phone.
On the other hand, among women who used hormonal contraceptives for short periods, the excess risk of breast cancer disappeared rapidly after use was stopped, the researchers said.
IUDs infused with hormones also appear to pose a risk, Morch said, so “so there’s a lot of things to take into account when deciding what type of contraception to use. Contraception itself is a benefit, of course, but this study indicates it might be worth considering an alternative to hormone contraception, like the copper intrauterine device or barrier methods like condoms.”
“If you compare this to other risks, such as obesity and being overweight, there’s more of a risk with obesity than if you take a few years of oral contraceptives,” Rao told Reuters Health by phone.
“There’s no need to panic based on these results,” said Morch, “We don’t want women dropping their contraception without having something different to go to. And there are alternatives.”
SOURCE: bit.ly/2jUGTHR The New England Journal of Medicine, online December 6, 2017.
Our Standards: The Thomson Reuters Trust Principles.