• Posted February 5, 2025

The Pill Protects Against Ovarian Cancer, Study Says

The Pill prevents pregnancy -- and maybe ovarian cancer, too, a new study suggests.

Women who’ve ever used the contraceptive pill have a 26% lower risk of ovarian cancer, researchers say.

Women who used the pill after age 45 benefit even more, with a 43% lower risk of ovarian cancer, according to findings published in the International Journal of Gynecological Cancer.

The hormones in the birth control pill work in part by stopping or reducing ovulation, the process by which eggs are released from the ovaries.

“This poses the question as to whether interventions that reduce the number of ovulations could be used as a potential target for prevention strategies for ovarian cancer,” investigator Amanda Lumsden, a research fellow with the University of South Australia, said in a news release.

The discovery of the Pill’s potential protective powers resulted from an effort to use AI to identify risk factors for ovarian cancer.

“Ovarian cancer is notoriously diagnosed at a late stage, with about 70% of cases only identified when they are significantly advanced,” Lumsden said.

“Late detection contributes to a survival rate of less than 30% over five years, in comparison to more than 90% for ovarian cancers that are caught early,” she continued. “That’s why it’s so important to identify risk factors.”

For the study, researchers analyzed data on more than 221,000 women participating in the UK Biobank, a long-term health research project.

During a follow-up of nearly 13 years, 1,441 women developed ovarian cancer. Researchers dug deep to figure out what aspects of their lives and health might have increased their cancer risk.

“We included information from almost 3,000 diverse characteristics related to health, medication use, diet and lifestyle, physical measures, metabolic, and hormonal factors, each measured at the start of the study,” lead investigator Iqbal Madakkatel, a research associate in machine learning at the University of South Australia, said in a news release.

The analysis also found that women who’d given birth to two or more children had a 39% lower risk of developing ovarian cancer, compared to those who had not had children.

Further, researchers discovered some characteristics of red blood cells and liver enzymes in the blood associated with ovarian cancer risk.

“It was particularly interesting that some blood measures -- which were measured on average 12.6 years before diagnoses -- were predictive of ovarian cancer risk, because it suggests we may be able to develop tests to identify women at risk at a very early stage,” Madakkatel said.

The study also confirmed some risk factors already suspected for ovarian cancer, including excess weight and taller stature.

The findings are in line with a theory of ovarian cancer first floated in 1971 which argued that “incessant ovulation” might promote the growth of abnormal pre-cancerous cells, researchers noted.

Other mammals only ovulate during breeding seasons, and ovarian cancer is rare among these species, the theory holds.

“It is possible that by using the contraceptive pill to reduce ovulations or by reducing harmful adiposity, we may be able to lower to risk of ovarian cancer,” senior researcher Elina Hypponen, a professor of nutritional and genetic epidemiology with the University of South Australia, said in a news release.

“But more research is needed to establish the best approaches to prevention, as well as the ways in which we can identify women most at risk,” she concluded.

More information

Planned Parenthood has more on how the birth control pill works.

SOURCE: University of South Australia, news release, Feb. 2, 2025