The risk of premature menopause induced by chemotherapy for early breast cancer.

The objectives of this retrospective case series were to determine the prevalence and timing of menstrual abnormalities in early-stage breast cancer patients undergoing adjuvant methotrexate or anthracycline-based chemotherapy and to more fully assess the possible mechanism of the amenorrhea reported after chemotherapy. One hundred forty-two premenopausal patients undergoing adjuvant chemotherapy were analyzed for patient age, breast cancer stage, type of chemotherapy, and menstrual abnormalities before, during, and after chemotherapy completion. A 24-month minimum follow-up after chemotherapy completion was available for all patients. One hundred nine of 142 patients were evaluable. Sixty-nine patients (46 node negative, 23 node positive) received methotrexate-based chemotherapy, 33 patients (3 node negative, 30 node positive) received anthracycline-based chemotherapy, and 7 patients received both treatments (all node positive). Amenorrhea occurred in about a third of patients during chemotherapy (methotrexate groups 31%, anthracycline group 33%), and a higher proportion were amenorrheic 1 year after chemotherapy was completed (methotrexate group 45%, anthracycline group 46%). Abnormalities were more likely to occur in older premenopausal patients (Chi square = 6.18, p < 0.05), although 28% of patients under age 35 developed persistent abnormal menses. In some amenorrheic patients, follicle-stimulating hormone (FSH) levels were decreased within 6 months of chemotherapy (24.4 IU). The levels tended to be higher after chemotherapy (59.1 IU), suggesting ovarian failure. Menstrual abnormalities and menopause will frequently occur in premenopausal early-stage breast cancer patients, with 30% of all patients amenorrheic 1 year after chemotherapy.