Is there a link between ovulation induction and cancer?

Although there have been no clinical trials to conclusively establish a cause-and-effect relationship between ovulation induction with clomiphene citrate or gonadotropins and cancer, evidence derived from prospective and cohort studies suggests the following:

Ovarian cancer: No correlation between fertility drugs and ovarian cancer exists, but nulligravid women and those with borderline ovarian tumors or certain tumor histologies may be at increased risk.

Breast cancer: Studies to date have had conflicting results, showing both increases as well as decreases in risk. Given that breast cancer is widely held to have a hormonal etiology, further studies examining a possible association between the disease and ovulation-inducing agents are needed.

Brinton LA, Moghissi KS, Scoccia B, et al. Ovulation induction and cancer risk. Fertil Steril. 2005;83:261-274.