Use of fertility drugs and risk of endometrial cancer in an Italian case–control study

The objective of this study was to analyse time-related aspects of the use of fertility drugs related to the risk of endometrial cancer using data from a case-control study conducted between 1992 and 2006 in Italy. The study included 454 cases (median age, 60 years; range, 18-79) with incident, histologically confirmed endometrial cancer and 908 female controls (median age, 61 years; range 19-79) admitted to the same network of hospitals as cases for a wide spectrum of acute, non-neoplastic conditions. Controls were frequency matched to cases with a 2:1 ratio for age and study centre. Information was collected by trained interviewers using a structured questionnaire. We calculated odds ratios (ORs) and the corresponding 95% confidence intervals (CI) using conditional logistic regression models adjusted for major relevant covariates. The OR of endometrial cancer for ever use of fertility drugs was 3.26 (95% CI, 1.07-9.95). The risk was higher for duration of use 12 months or more (OR=6.10; 95% CI, 0.96-38.6), time since last use 25 years or less before the interview (OR=5.30; 95% CI, 1.12-25.1), and for age at first use less than 30 years (OR=5.14; 95% CI, 1.13-23.4). The association was apparently stronger in ever-gravid (OR=6.50; 95% CI, 1.10-38.3) than in nulligravid (OR=2.83; 95% CI, 0.32-25.0) women. Our data support earlier findings of an increase in risk of endometrial cancer with duration of use of fertility drugs.