Despite increasing evidence of benefit from adjuvant chemotherapy, older women with breast cancer are commonly given less aggressive treatment than younger patients. Conflicting prior data regarding age-related toxicity prompted this prospective study. Forty-four women (aged 35-79 years) with early-stage breast cancer were treated with four cycles of adjuvant therapy with doxorubicin 60 mg/m(2) i.v. and cyclophosphamide 600 mg/m(2) i.v. every 21 days. They were monitored for myelosuppression, cardiotoxicity, and decrease in quality of life. Pharmacokinetics were analyzed using cycle 1 plasma samples. Bone marrow granulocyte and macrophage colony-forming units (CFU-GM) were assayed in vitro for dose response to 4-hydroperoxycyclophosphamide and doxorubicin before cycle I. There was moderate evidence of age-related decrease in nadir absolute neutrophil count (ANC) when age was viewed as a continuous variable. On average there was a 10/mu l drop in cycle 1 nadir ANC for every year increase in age (p = 0.02). However, when age was viewed as a categorical variable (age < 65 vs. 165 years), a similar proportion of women in each group reached an ANC < 100 (18% vs. 19%). Neither neutropenic complications, alteration in cardiac function, nor change in quality of life scores were significantly age related (p > 0.12). Pharmacokinetic analyses did not demonstrate age-related differences in the clearance of either doxorubicin or cyclophosphamide (p > 0.8). Pharmacodynamic analysis of individual patient bone marrow progenitor cell sensitivity did not reveal any correlation with age (p > 0.48). In women undergoing adjuvant therapy for breast cancer; no clinically significant age-related trends in toxicity were observed These data suggest that older age alone should not exclude patients from receiving adjuvant therapy with doxorubicin and cyclophosphamide.
