Oral Contraceptives Offer Long-Term Protection Against Ovarian Cancer

The use of oral contraceptives have linked it to increased risk for breast cancer

Oral contraceptives offer long-term protection against ovarian cancer, with the reduction in risk persisting for more than 30 years. This finding, from a huge analysis of 45 studies reported in the January 25 issue of The Lancet, offers "unequivocal good news" says an accompanying commentary. A hard-hitting Lancet editorial published alongside says that the finding has "important public health implications" and calls for oral contraceptives to be made available over the counter.

In the article, researchers from the Collaborative Group on Epidemiological Studies of Ovarian Cancer analyzed individual data on more than 100,000 women from 21 countries. They report that 10 years of oral contraceptive use was estimated to reduce the incidence of ovarian cancer from 1.2 to 0.8 per 100 users and reduce death from ovarian cancer from 0.7 to 0.5 per 100 users. Expressing these figures another way, the researchers, headed by Valerie Beral, MD, from Oxford University, Oxford, United Kingdom, point out that if 5000 women used oral contraceptives for 1 year, approximately 2 cases of ovarian cancer and 1 death from ovarian cancer before the age of 75 years would be prevented.

Dr. Beral and colleagues estimate that in the last 50 years during which oral contraceptives have been available, approximately 200,000 cases of ovarian cancer and 100,000 deaths have been prevented worldwide. As use of these products continues to increase, they estimate that for the next few decades, oral contraceptives could prevent 30,000 cases of ovarian cancer annually.

"These findings set a new standard in primary prevention for a deadly cancer," the editorial comments. "There are few drugs available that confer powerful and long-lasting protection against a highly lethal malignancy after such a short exposure."

However, an accompanying commentary is more cautious. Eduardo L. Franco, PhD, from McGill University in Montreal, Canada, and his wife, Eliane Duarte-Franco, MD, from the Institut National de Sante Publique du Quebec, also in Montreal, say that "women and their health-care providers are once gain at a balancing act of judging risks versus benefits."

In addition to ovarian cancer, oral contraceptives have also shown a protective effect against endometrial and colorectal cancer. However, they have also been linked with an increased risk for breast and cervical cancer, they point out, and "calculation of the next effect on women's health is fraught with uncertainties."

Source: Lancet. 2008;371:275, 277-278, 303-314. Click clinical tests.