Purpose: This prospective study assessed the impact of 2 years of aromatase inhibitor (AI) therapy on the incidence of ovarian function recovery (OFR) in women age 40 to 49 with estrogen receptor-positive breast cancer who were premenopausal at diagnosis and who underwent chemotherapy-induced amenorrhea during adjuvant treatment.
Patients and methods: Women age 40 to 49 with estrogen receptor-positive breast cancer who had ceased menstruating with adjuvant cyclophosphamide-based chemotherapy, had postmenopausal serum estradiol (E2), and had received tamoxifen for ≥ 1 year were treated with letrozole (2.5 mg) daily for ≥ 2 years. Serum follicle-stimulating hormone (FSH) and E2 were measured at baseline and over 2 years. A general linear model was used to assess serial FSH by OFR. Logistic regression was used to assess baseline predictors and OFR.
Results: The study enrolled 177 women (145 women age 45 to 49 years and 32 women age 40 to 44 years). Of 173 evaluable patients, 67 (39%; 95% CI, 31% to 46%) regained ovarian function; 11 of these patients (6%; 95% CI, 3% to 10%) resumed menses, and 56 of these patients (32%; 95% CI, 25% to 39%) developed premenopausal E2 without menses. Among AI-naïve patients, serial FSH significantly increased over time (P < .001), did not vary significantly by OFR status (P = .55), but showed mild evidence of a decrease after month 12 for those who resumed menses (P = .0989). Age less than 45 years and inhibin B were significant multivariable baseline predictors of OFR.
Conclusion: These results emphasize the challenge in determining definitive menopause in women with chemotherapy-induced amenorrhea. 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.
© 2016 by American Society of Clinical Oncology.