PCOS and Infertility: Is a Breast Cancer Drug the Answer?

Letrozole, a breast cancer drug not indicated for induction of ovulation, outperformed clomiphene as a fertility treatment for women with polycystic ovary syndrome (PCOS), a study published in the New England Journal of Medicine found.

Women with PCOS who received letrozole were more likely to successfully ovulate and give birth than women who underwent fertility treatment with clomiphene.

Pertinent Points

- For women with PCOS, letrozole proved superior to clomiphene as a fertility treatment in a study involving 750 women.

- Those using letrozole were more likely to ovulate and to give birth than those who used clomiphene.

The study enrolled 750 infertile women aged 18 to 40 years with PCOS who had no major medical disorders and who were not taking confounding medications, such as sex steroids, other infertility drugs, or insulin sensitizers. Half of the women received letrozole and half received clomiphene, with each of the treatment protocols lasting for up to five cycles.

Among the women who received letrozole, 27.5% gave birth, compared with 19.1% of women who used clomiphene (103 of 374 vs 72 of 376; P=0.007; rate ratio for live birth, 1.44; 95% confidence interval, 1.10 to 1.87). There was no significant difference in the overall incidence of congenital anomalies, although the authors did report that there were four major congenital anomalies in the letrozole group compared with just one in the clomiphene group (P=0.65).

Ovulation rates were significantly higher among the women who received letrozole, with 61.7% of treatment cycles resulting in ovulation. Among those using clomiphene, 48.3% of treatment cycles resulted in ovulation.

There were no significant differences in pregnancy loss, with 49 of 154 pregnancies in the letrozole group ending in miscarriage, compared with 30 of 103 pregnancies in the clomiphene group. In addition, the incidence of twin pregnancies was not significantly different between the two treatment groups.

As for adverse effects from the treatments, clomiphene users experienced a higher incidence of hot flushes, while letrozole users were more likely to experience fatigue and dizziness.