Letrozole tied to ovarian function recovery in chemo

(HealthDay)—Some women aged 40 to 49 years with estrogen receptor-positive breast cancer who undergo chemotherapy-induced amenorrhea regain ovarian function with letrozole, according to a study published online Feb. 16 in the Journal of Clinical Oncology.

Lea K. Krekow, M.D., from Texas Oncology-The Breast Care Center of North Texas in Bedford, and colleagues conducted a prospective study to examine the impact of two years of aromatase inhibitor (AI) therapy on the incidence of ovarian function recovery (OFR). Women aged 40 to 49 years with estrogen receptor-positive breast cancer who had ceased menstruating with adjuvant cyclophosphamide-based chemotherapy, and had received tamoxifen, were treated with letrozole daily for at least two years. One hundred seventy-seven women were enrolled (145 aged 45 to 49 years and 32 aged 40 to 44 years).

The researchers found that 39 percent of the 173 evaluable patients regained ovarian function; 11 of these (6 percent) resumed menses. Thirty-two percent developed premenopausal estradiol without menses. Serial follicle-stimulating hormone significantly increased over time among AI-naive patients (P < 0.001), with no variation by OFR status (P = 0.55); for those who resumed menses there was mild evidence of a decrease after month 12 (P = 0.0989). Significant predictors of OFR were age <45 years and inhibin B.

"These results emphasize the challenge in determining definitive menopause in women with chemotherapy-induced amenorrhea," the authors write. "The risk of OFR during treatment with AIs in amenorrheic women in their 40s is high, and AI therapy should be avoided in these patients."

Several authors disclosed financial ties to pharmaceutical companies, including Novartis, which manufactures letrozole and funded the study.