Ocs provide long-lasting protection against ovarian cancer

Oral contraceptives (OCs) provide protection against ovarian cancer for up to 30 years or more after women stop taking them, according to a collaborative reanalysis of data from 45 epidemiologic studies from 21 countries. And the longer a woman takes the pills, the greater the reduction in risk she enjoys (P<.0001).

The studies involve a total of 23,257 women with ovarian cancer and 87,303 women without. Of those, 7,308 women with cancer and 32,717 controls had ever used OCs (average duration of use: 4.4 and 5.0 years, respectively).

The authors of the reanalysis calculated proportional risk reductions per 5 years of use of 29% (95% CI, 23%–34%) for users who ceased taking the pills less than 10 years previously, 19% (14%–24%) for users who ceased 10 to 19 years previously, and 15% (9%–21%) for women who ceased use 20 to 29 years previously. Risk reductions were similarly proportional for women who had taken OCs during the 1960s, '70s, and '80s, but the researchers pointed out that the amount of estrogen in pills produced during the '60s was more than double that in the '80s versions.

Collaborative Group on Epidemiological Studies of Ovarian Cancer. Ovarian cancer and oral contraceptives: collaborative reanalysis of data from 45 epidemiological studies including 23,257 women with ovarian cancer and 87,303 controls. Lancet. 2008;371:303-314.

Commentary by Paula J. Adams Hillard, MD,

Professor, Department of Obstetrics and Gynecology,Stanford University School of Medicine.

The fact that oral contraceptives confer protection against ovarian cancer has been established formany years. However, many of our patients are stillunaware of this benefit. This analysis confirms thebenefit, and reminds us as clinicians that we need tocontinue to spread this good news.