Ovarian cancer deaths plummet, thanks to the pill

Birth control pills granted women autonomy over their bodies and, arguably, kicked off the women's liberation movement of the 1960s. Now, a new study in Annals Of Oncology suggests that the Pill has yet another trick up its sleeve — the ability to help prevent ovarian cancer. The findings suggest that ovarian cancer deaths are plummeting across Europe, "due to more uniform use of oral contraceptives," said coauthor Carlo La Vecchia of the University of Milan, in a statement.

The Pill is more or less a bundle of hormones — usually estrogen, with a pinch of progestin tossed in, though progestin-only forms also exist. These hormones effectively trick the body into believing that it is already pregnant, preventing any new pregnancies from happening. But that's not the Pill's only effect on women's bodies. Prior studies have found that the hormones in the Pill likely decrease the risk of ovarian cancer while, paradoxically, increasing the risk of breast, cervical, and liver cancer.

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Breast cancer risk seems to be tied up in any sort of broad exposure to hormones. Women who begin menstruating early or experience menopause late, for instance, are also at increased risk — likely because their breast tissue spends more time exposed to high levels of hormones. Ditto for cervical and liver cancer: the longer women are exposed to sex hormones, whether through the Pill or the body's natural processes, the higher their risk of most types of cancer seems to be.

And then there's ovarian cancer. Multiple studies have found that the Pill decreases risk of ovarian cancer, and that the longer women used the Pill the lower their risk became. One study found that the risk of ovarian cancer decreased by 10 percent after one year of use and by 50 percent after five years of use. This effect doesn't seem to be tied to estrogen dose — one recent study found that the risk of ovarian cancer declined equally, no matter how much estrogen or progestin was in the pill. Scientists still aren't sure why the Pill has this odd effect, but one animal study found that the progestin in birth control pills can convince damaged ovarian cells to die before they cause cancer.

To figure out how many lives had been saved by the Pill, researchers collected data on ovarian cancer deaths between 1970 and the present. They found that, within the 28 countries of the European Union, death rates decreased by 10 percent between 2002 and 2012. In the United States, the decline was even more pronounced, with a 16 percent drop over the same time period. Based on these figures, the researchers predict that Europe will experience an additional decline of 10 percent by the year 2020, and that the U.S. will see another 15 percent drop. In each instance, the decline in ovarian cancer rates was strongly correlated to oral contraceptive use.

"The findings of Professor La Vecchia and his colleagues are important as they show how past use of hormone treatments has an impact on the mortality from ovarian cancer at the population level," said Paolo Boffetta of Mount Sinai Hospital in New York, who was not involved in the study, in a press statement. "As our understanding of preventable causes of this major cancer progresses, early detection strategies are being developed and novel therapeutic options become available, we enhance our ability to reduce ovarian cancer mortality."

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