Use of Clomiphene Citrate to Induce Ovulation Associated with Higher Risk of Uterine Cancer, Study Says

Main Category: Women's Health / Gynecology
Article Date: 28 Apr 2005 - 9:00 PDT

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The use of the selective estrogen receptor modulator clomiphene citrate to induce ovulation in women with fertility problems is associated with an increased risk of uterine cancer, according to a study published in the April 1 issue of the... American Journal of Epidemiology, Reuters Health reports. Michelle Althuis of the division of cancer epidemiology and genetics at the National Cancer Institute and colleagues studied 8,431 women who had been evaluated for infertility at five U.S. metropolitan-area fertility clinics between 1965 and 1988. Thirty-nine of the women were diagnosed with uterine cancer during the course of the study, a 56% higher uterine cancer prevalence than in the general population. In addition, the 3,280 women studied who were exposed to clomiphene citrate were more than twice as likely to develop uterine cancer as the women involved in the study who were not exposed to the drug (Reuters Health, 4/25). However, the rate ratios did not reach traditional levels of statistical significance (Althuis et al., American Journal of Epidemiology, 4/1). The risk of uterine cancer was even higher for women who took larger doses of clomiphene, took the hormone for longer periods of time or took the drug more than 20 years ago. The highest risk of uterine cancer among women given clomiphene in the study occurred in obese women who had never been pregnant at the start of the study. However, the risk was not statistically significant, and obese women who had never been pregnant had an increased risk of uterine cancer even without taking clomiphene. The authors said additional research is needed, but they hypothesized that clomiphene increases uterine cancer risk by indirectly increasing estrogen levels. High levels of estrogen previously have been "definitively linked to uterine cancer," according to the study (Reuters Health, 4/25).

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