Birth control pills give long-term protection against ovarian cancer, a new study finds. Past work has shown that birth control pills afford some protection against ovarian cancer, but researchers did not know how long this beneficial effect lasted. In a new study led by Valerie Beral from the Cancer Research UK Epidemiology Unit at Oxford University, researchers compiled data from 45 previous studies that included about 23,000 women with ovarian cancer and 87,000 without it. Just over 30 percent of the women with cancer and 37 percent of those without cancer had taken the pill for some period of time. They found that using the pill for a decade or more reduced ovarian cancer risk by almost one-third and the protection lasted 30 years after pill usage had stopped. They also found that the longer a woman was on the pill the more it reduced cancer risk. This beneficial effect was consistent, regardless of ethnicity, education, or alcohol and tobacco consumption, they found.

BOTTOM LINE: “Women do not have to worry about bad side effects from taking the pill,” said Beral. “We know now that the pill actually offers protection against ovarian cancer.”

CAUTIONS: This is the first study to look at long-term benefits of the pill and more work is needed to confirm the results. The study also looks at just ovarian cancer; other side effects have to be taken into consideration to fully understand whether the positives outweigh the negatives.

WHAT’S NEXT: Beral’s group wants to look at the effect of the pill in reducing endometrial cancer risk.

WHERE TO FIND IT: The Lancet, Jan. 26