The objectives of this retrospective case series were to determine the prev
alence and timing of menstrual abnormalities in early-stage breast cancer p
atients undergoing adjuvant methotrexate or anthracycline-based chemotherap
y and to more fully assess the possible mechanism of the amenorrhea reporte
d after chemotherapy. One hundred forty-two premenopausal patients undergoi
ng adjuvant chemotherapy were analyzed for patient age, breast cancer stage
, type of chemotherapy and menstrual abnormalities before, during, and afte
r 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) r
eceived methotrexate-based chemotherapy, 33 patients (3 node negative, 30 n
ode positive) received anthracycline-based chemotherapy, and 7 patients rec
eived both treatments tall node positive). Amenorrhea occurred in about a t
hird of patients during chemotherapy (methotrexate groups 31% anthracycline
group 33%), and a higher proportion were amenorrheic 1 year after chemothe
rapy was completed (methotrexate group 45%, anthracycline group 46%). Abnor
malities were more likely to occur in older premenopausal patients (Chi squ
are = 6.18, p < 0.05), although 28% of patients under age 35 developed pers
istent abnormal menses. In some amenorrheic patients, follicle-stimulating
hormone (FSH) levels were decreased within 6 months of chemotherapy (24.4 I
U). The levels tended to be higher after chemotherapy (59.1 IU), suggesting
ovarian failure. Menstrual abnormalities and menopause will frequently occ
ur in premenopausal early-stage breast cancer patients, with 30% of all pat
ients amenorrheic 1 year after chemotherapy.