Objective: To assess the risk of invasive ovarian cancer among infertile women treated with fertility drugs.
Design: A case-control study.
Setting: Nationwide data based on public registers.
Patient(s): All Danish women (below the age of 60 years) with ovarian cancer during the period from 1989 to 1994 and twice the number of age-matched population controls. Included in the analysis were 684 cases and 1,721 controls.
Main outcome measure(s): Influence of parity, infertility, and fertility drugs on the risk of ovarian cancer after multivariate confounder control. Risk measure(s): odds ratios (OR) with 95% confidence intervals.
Result(s): Nulliparous women had an increased risk of ovarian cancer compared with parous women: OR 1.5 to 2.0. Infertile, nontreated nulliparous women had an OR of 2.7 (1.3 to 5.5) compared with noninfertile nulliparous women. The OR of ovarian cancer among treated nulliparous women was 0.8 (0.4 to 2.0) and among treated parous 0.6 (0.2 to 1.3), compared with nontreated nulliparous and parous infertile women, respectively.
Conclusion(s): Nulliparity implies a 1.5- to 2-fold increased risk of ovarian cancer. Infertility without medical treatment among these women increased the risk further. Among parous as well as nulliparous women, treatment with fertility drugs did not increase the ovarian cancer risk compared with nontreated infertile women.