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

Am J Obstet Gynecol. 2005 Sep;193(3 Pt 1):668-74. doi: 10.1016/j.ajog.2005.01.091.


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.

MeSH terms

  • Clomiphene / adverse effects*
  • Colonic Neoplasms / chemically induced
  • Colonic Neoplasms / epidemiology*
  • Female
  • Fertility Agents, Female / adverse effects*
  • Gonadotropins / adverse effects*
  • Humans
  • Incidence
  • Melanoma / chemically induced
  • Melanoma / epidemiology*
  • Risk Assessment
  • Thyroid Neoplasms / chemically induced
  • Thyroid Neoplasms / epidemiology*
  • Uterine Cervical Neoplasms / chemically induced
  • Uterine Cervical Neoplasms / epidemiology*


  • Fertility Agents, Female
  • Gonadotropins
  • Clomiphene