Birth control pills may reduce endometrial cancer risk

Can birth control pills reduce the risk of endometrial cancer? Using oral contraceptives, even for only a few years, can provide significant long-term protection against endometrial cancer. Beral, who led the study, said: "The strong protective effect can last for decades after stopping oral contraceptive use, which means that women who use oral contraceptives in their 20s or younger can still benefit when they are in their 50s or older, when cancer is most common.

In the study, researchers analyzed data from 36 studies involving more than 136,000 women, including about 27,000 women who had already developed endometrial cancer. Overall, the researchers found that every five years of oral contraceptive use was associated with about a 25 percent lower risk of endometrial cancer, suggesting that the reduced risk lasts more than 30 years after stopping oral contraceptive use.

Among women living in high-income countries, the authors found that 10 years of oral contraceptive use reduced the risk of endometrial cancer from 2.3 cases per 100 women to 1.3 cases per 100 women by age 75. In addition, the researchers estimate that oral contraceptive use has prevented approximately 400,000 cases of endometrial cancer over the past 50 years, including 200,000 in the past decade.

Beral also believes that more cases of endometrial cancer might have been prevented by oral contraceptives if it weren't for obesity, which increases disease risk. In an accompanying editorial, Wentzensen and Gonzalez characterize the results as "impressive and instructive," but they caution that it's too early to know whether the overall health benefits of oral contraceptive use warrant specific recommendations for cancer prevention. Oral contraceptives have been linked to a risk of blood clots, and different versions and doses are associated with different risks of heart attacks and strokes, Wentzensen and Gonzalez note.