Epithelial ovarian cancer and induction of ovulation

The possible link between ovulation-inducing agents and ovarian cancer has been the focus of considerable research effort over the past decade. Epidemiological studies addressing this issue have varied in their ability to achieve adequate sample sizes, obtain accurate measures of subfertility and fertility drug use, and eliminate potential bias due to confounding variables. Despite these methodological challenges, nulliparity has consistently been associated with increased rates of epithelial ovarian cancer. An additional modest effect of subfertility has been suggested by some studies, particularly among women who remain childless despite prolonged non-pharmacological attempts to conceive. Type of subfertility may also impact on ovarian cancer risk: ovulatory disorders, endometriosis and unexplained subfertility have all been associated with increased rates of the disease. However, most studies have shown no overall increased risk of epithelial ovarian cancer in women exposed to ovulation-inducing agents, irrespective of the type of fertility drugs used and duration of treatment. While results are generally reassuring, there is a clear need for larger studies employing longer periods of follow-up, detailing precisely the types, doses and duration of treatments patients have received, and controlling for potential confounding reproductive factors. While uncertainties persist, patients undergoing ovulation induction should be informed of the possible increased risk of ovarian cancer following treatment, but it should be emphasised that this risk is doubled at most. Short courses of ovulation induction are probably preferable but there is no evidence for post-treatment screening for ovarian cancer in these patients.