A review of infertility and its treatment in the etiology of female reproductive and other cancers

Although infertile women do not appear to have an increased risk of cancer when all sites are combined, nulliparity is associated with an increased risk of cancers of the breast, ovary, and endometrium; elevated risks of female reproductive cancers have been reported in some studies; and use of fertility drugs was found to significantly increase the risk of ovarian cancer in a pooled analysis of three case-control studies and in one cohort study. Because specific causes of infertility were not always classified precisely, fertility drugs were not evaluated in many studies, the number of cases is limited, and problems in separating effects of nulliparity, infertility, and fertility drug usage remain, these results should be interpreted cautiously. With an estimated 10% of couples unable to conceive and the use of fertility drugs increasing dramatically, there is a need to clarify the role of infertility and fertility drugs in the induction of cancer.