There has long been evidence linking hormonal contraception to breast cancer, but it seems it's not just certain kinds of pills we should be worried about. According to a large new study, all forms of the pill and other hormonal contraception carry an increased risk of breast cancer.
Previously it was thought that newer forms of pill and devices, which contain less oestrogen than in the past, would be safer. But the research suggests that even progesterone-only contraceptives may raise the breast cancer risk.
The study, published in the New England Journal of Medicine, found that women who use hormonal contraception, including the pill and IUDs, run a 20% added risk of developing breast cancer compared with women who don't. Among those taking the pill for five years, this would equate to one extra case for every 1500 women. While the risk is significant, it's still small for women not already at high risk of developing the disease.
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The huge piece of research, which followed 1.8 million Danish women under 50 for more than a decade, also found that the longer a woman takes hormonal contraception, the greater the risk.
Women who had used it for more than a decade showed a 38% additional risk compared with nonusers, while there was no increased risk among those who had used hormones for less than a year, the New York Times reported. The risk was also greater among women over 40.
Dr Marisa Weiss, an oncologist who founded US website breastcancer.org and wasn't involved in the study, said the study was important "because we had no idea how the modern day pills compared to the old-fashioned pills in terms of breast cancer risk, and we didn’t know anything about IUDs." She told the New York Times: “Gynecologists just assumed that a lower dose of hormone meant a lower risk of cancer. But the same elevated risk is there.”
A drawback of the research was that it didn't take into account other factors that may influence breast cancer risk, such as physical activity, alcohol consumption and breastfeeding. It's also important to bear in mind the potential benefits of certain hormonal contraceptives and weigh these against the small breast cancer risk.
These include “substantial reductions in the risks of ovarian, endometrial and colorectal cancers in later life," Professor David Hunter, from the Nuffield Department of Population Health, told the Guardian.
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