FDA Highlights: Letrozole aids births in women with PCOS

by Bruce Sylvester: Estrogen blocking letrozole treatment results in higher birth rates in women with polycystic ovary syndrome (PCOS) than standard-therapy clomiphane, researchers reported on July 9, 2014 in the New England Journal of Medicine/NEJM.

As background, the authors noted that 5 to 10 percent of reproductive-age women have PCOS. It is the most common cause of female infertility.

“Clomiphine has its drawbacks,” said lead author Richard Legro, MD, professor of obstetrics and gynecology at Penn State University College of Medicine in State College, Pennsylvania. “It’s only 22 percent successful with up to six cycles of treatment in producing a successful birth, it has a high multiple-pregnancy rate in comparison to unassisted conception, and it has side effects including hot flashes and mood changes.”

The investigators enrolled 750 infertile women with PCOS between 18 and 40 years old who wanted to conceive. The subjects were randomized to either clomiphene or letrozole. They were treated for up to five cycles, with increased dosing in each cycle.

Letrozole subjects achieved had a higher live birthrate, 27.5 percent, that clomiphene subjects, 19.1 percent.

Also, at each monthly check ovulation rates were significantly higher with letrozole than with clomiphene.

There were fewer twin pregnancies among letrozole subjects, 3.9 percent, than clomiphene subjects,   6.9 percent.

Clomiphene subjects had a significantly higher incidence of hot flashes, and letrozole subjects had a significantly higher incidence of fatigue and dizziness.

For both treatments, birth defects were rare, rates were comparable between both drugs and they did not exceed rates from studies of women who conceive without treatment.