Melanoma, thyroid, cervical, and colon cancer risk after use of fertility drugs

Objective: This study was undertaken to evaluate melanoma, thyroid, colon, and cervical cancer risks after clomiphene or gonadotropins. Study design: Retrospective cohort of 8422 women (155,527 women-years) evaluated for infertility (1965-1988). Through 1999, cancers were ascertained by questionnaire, cancer and death registries. Poisson regression estimated adjusted rate ratios (RRs). Results: Clomiphene use did not significantly increase risk of melanoma (RR = 1.66; 95% CI, 0.9- 3.1), thyroid (RR = 1.42; 95% CI, 0.5-3.7), cervical (RR = 1.61; 95% CI, 0.5-4.7), or colon cancer (RR = 0.83; 95% CI, 0.4-1.9). We found no relationship between clomiphene dose or cycles of use and cancer risk at any site. Clomiphene use may impart stronger effects on risks of melanoma (RR 2.00; 95% CI, 0.9-4.6) and thyroid cancer among women who remained nulliparous (RR 4.23; 95% CI, 1.0- 17.1). Gonadotropins did not increase cancer risk for these sites. Conclusion: Fertility drugs do not appear to have strong effects on these cancers. Nonetheless, follow-up should be pursued to assess long-term risks and to monitor effects among women who remain nulliparous. (c) 2005 Mosby, Inc. All rights reserved.