among women who use hormone-based birth control methods, many women were left wondering: How significant is the risk, and what are the alternatives?
The answer will be different for each woman and will depend on such factors as her age and general healthand her other risks for breast cancer. But many doctors who prescribe contraceptives say there’s no cause for alarm — and no one should throw away her pills and risk an unwanted pregnancy.
The increased breast cancer risk identified among hormone users in the study was small. For the vast majority of women in their 20s and 30s, breast cancer is rare to begin with, so this modest increase would not amount to many additional cases.
And while birth control pills may slightly raise the odds of breast cancer — and have been associated with increases in cervical cancer, as well — the contraceptive’s relationship with cancer is complex.
Oral contraceptives appear to reduce the incidence of some less common reproductive cancers, like endometrial cancer and ovarian cancer, which is often detected at an advanced stage, when it is hard to treat. There is some evidence that birth control pills may also reduce the odds of colorectal cancer.
A British study of over 46,000 women who were recruited in 1968, during the early days of the pill, and followed for up to 44 years found that despite increases in breast and cervical cancers among those who used the pill, the effect on overall cancer rates was neutral, because other cancers were reduced.
“In aggregate, over a woman’s lifetime contraceptive use might prevent more cancers” than it causes, said David J. Hunter, a professor of epidemiology and medicine at University of Oxford in Britain, who wrote a commentary on the Danish study published in The New England Journal of Medicine last week.
“There is good data to show that five or more years of oral contraceptive use substantially reduces ovarian cancer and endometrial cancer risk, and may reduce colorectal cancer,” he said. “And the protection persists for 10 or 20 years after cessation.”
While the new study’s findings about breast cancer are important, “these results are not a cause for alarm,” said Dr. JoAnn E. Manson, a professor of women’s health at Harvard Medical School and chief of preventive medicine at Brigham and Women’s Hospital.
“It’s really problematic to look at one outcome in isolation. Hormonal contraception has a complex matrix of benefits and risks, and you need to look at the overall pattern.”
Dr. Hal Lawrence, an obstetrician-gynecologist and chief executive officer of the American College of Obstetricians and Gynecologists, said his biggest concern was that the study would “scare women away from effective contraception,” resulting in unwanted pregnancies.
“We’re never going to eliminate all the potential risks that come with medication,” Dr. Lawrence said. “But we know a lot of the benefits, and the No. 1 benefit is preventing unintended pregnancies and the health and socio-economic risks that go along with that.”
In some ways, the results of the new study were not surprising. Research had linked birth control pills to a modest increase in breast cancer decades ago.
What was surprising was that the risk has persisted even with new pills that use lower doses of estrogen than the first generation of pills that came on the market — and that the increase in risk was experienced even by women who don’t take hormones orally, relying instead on implanted intrauterine devices that release a hormone “locally” into the uterus.
Many older women who have completed their families and are at higher risk for breast cancer because of their age turn to the IUD precisely because they want to minimize exposure to hormones.
So what are women to do?
Here’s some advice from top doctors who were interviewed about the implications of the new research.