Ovulation induction and risk of endometrial cancer: a pilot study

Objective: To determine whether women with endometrial carcinoma are more l ikely to have been exposed to fertility drugs, in particular clomiphene, th an healthy population controls. Study design: A nationwide case-control, pi lot study. About 128 living women 35-64 years old, with a histologicaly con firmed diagnosis of endometrial carcinoma that was first diagnosed and repo rted to The Israel Cancer Registry between I January 1989 and 31 December 1 992 were enrolled. The controls were 255 women from the same dialing areas selected by random digit dialing. A variety of demographic and clinical par ameters were compared between cases and controls. A multivariate logistic m odel, controlling for age, was used to assess the independent effects of fa ctors found to be significantly associated with endometrial cancer on univa riate analysis. Results: About 7 women with endometrial carcinoma (5.5%) an d 10 healthy controls (3.9%) reported that they had used any fertility drug (crude odds ratio (OR) 1.4; 95% confidence interval (CI) 0.47-4.2). Use of fertility drugs did not meet the criteria for entry into the logistic mode l. The following parameters were found to be independently associated with endometrial cancer controlling for age, European-American background OR 2.2 , (95% CI 1.3-3.7, P = 0.004); nulliparity OR = 2.7 (95% CI 1.1-6.5, P = 0. 03); history of infertility OR = 1.8 (95% Cl 1.0-3.3, P = 0.05); BMI greate r than or equal to 27 OR = 2.3 (95% CI 1.4-3.9, P = 0.001). The use of oral contraceptives and IUD were found to be protective, OR 0.29 and 0.37, resp ectively, (95% CI 0.14-0.61, P = 0.001 and 0.19-0.70, P = 0.003, respective ly). Conclusions: We found no evidence that the use of ovulation induction agents, including clomiphene citrate, are associated with a higher risk of endometrial carcinoma. The association between infertility drugs and endome trial carcinoma should be examined in other, larger studies. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.