We already know that birth control pills can effectively prevent pregnancy and treat the symptoms of a variety of health conditions like menstrual migraines, endometriosis, and uterine fibroids. Now, new research shows that oral contraceptives also have significant protective effects against endometrial cancer, preventing 200,000 cases of the disease in the last decade.
In the new study, published in the journal The Lancet Oncology, researchers looked at data from 27,276 women with endometrial (uterine) cancer and 115,743 women without it from 36 different studies. They estimate in their findings that 400,000 cases of endometrial cancer have been prevented due to women taking oral contraceptives in the past 50 years, and 200,000 of these prevented cases are from the last 10 years, averaging 20,000 averted cases annually.
The study shows that every five years of using oral contraceptives lowers the risk of endometrial cancer by around a quarter. Hormone doses in oral contraceptives have dropped through the years, but the new findings suggest that the amount of hormones in lower dose pills used today still offer a protective benefit.
Since oral contraceptives make the body think its pregnant, the amount of natural estrogen circulating in the body drops and lowers the risk of developing endometrial cancer.
The study also found that the longer the women used oral contraceptives, the greater their risk declined. Notably, the risk reduction continued for over 30 years after the women stopped using oral contraceptives, suggesting the protective effect is prolonged.
Oral contraceptives offer similar protection against ovarian cancer. The National Cancer Institute estimates that taking the pill for five years or longer may cut your ovarian cancer risk in half. That protection may last up to 25 years after you stop taking the pill. Studies even suggest the pill may protect against ovarian cancer in women with BRCA genetic mutations. Based on trends in the use of oral contraceptives, the number of ovarian cancer cases averted annually is expected to rise to at least 30,000 per year over the next few decades, according to a 2008 study published in The Lancet.
While studies have linked oral contraceptives with a slightly increased risk of breast and cervical cancers, the increase is only temporary and your risk returns to normal a few years after going off the pill.