Adjuvant Aromatase Inhibitors for Early Breast Cancer After Chemotherapy-Induced Amenorrhoea: Caution and Suggested Guidelines

Purpose Aromatase inhibitors (AIs) are now established as adjuvant therapy for early hormone receptor–positive breast cancer in postmenopausal women. Their use is sometimes extended to younger women after chemotherapy-induced amenorrhoea; we have audited this in one institution's breast unit, and we propose guidelines for use in such circumstances.Patients and Methods The use of aromatase inhibitors as adjuvant therapy in younger women age ≥ 40 with hormone receptor–positive early breast cancer and chemotherapy-induced amenorrhea has been audited clinically and biochemically.Results A total of 45 such women were identified in the audit, with a median age of 47 years (range, 39 to 52 years). Twelve women (27%) showed a return of ovarian function (10 renewed menses, one pregnancy, one biochemically premenopausal) after starting an AI. Median age at restart of ovarian function was 44 years (range, 40 to 50 years).Conclusion AIs may promote recovery of ovarian function in some women with chemotherapy-induced amenorrhea and should be used with caution. Biochemical monitoring of ovarian function requires highly sensitive immunoassays. Guidelines for the selection and delivery of adjuvant endocrine therapy in such patients are proposed.