Infertile women at lower risk of breast cancer

A prospective study involving a cohort of over 100,000 female registered nurses from the Nurses' Health Study II finds that women who are infertile due to ovulatory disorders are about 25% less likely to develop breast cancer than women who report no fertility problems (covariate-adjusted hazard ratio 0.75; 95% CI, 0.59-0.96).

Furthermore, women with ovulatory disorders who have received ovulation-induction therapy for their infertility are about 40% less likely to develop the disease (covariate-adjusted hazard ratio 0.60; 95% CI, 0.42-0.85). Researchers from Harvard studied the women who were between the ages of 25 and 42 at baseline from 1989 to 2001.

The study seems to confirm that anovulation decreases the risk of breast cancer. It also provides good news for many of these women by indicating that clomiphene does not increase the risk of breast cancer.

Terry KL, Willett WC, Rich-Edwards JW, et al. A prospective study of infertility due to ovulatory disorders, ovulation induction, and incidence of breast cancer. Arch Intern Med. 2006;166:2484-2489.