Adjuvant chemotherapy in stage-II breast cancer: an overview of the NSABP clinical trials.

Data derived from 1848 patients entered into three adjuvant chemotherapy protocols are presented. The three studies were performed sequentially and were designed to identify patient subsets responding to one, two, or three chemotherapeutic agents. Comparison of disease-free survival in patients receiving L-PAM or placebo disclosed that L-PAM was beneficial in patients less than or equal to 49 years of age, but not in women greater than or equal to 50 years. Further analysis indicated that the subset of patients less than or equal to 49 years with 1-3 positive nodes sustained the greatest increment in disease-free survival with single-agent L-PAM. The addition of 5-FU to L-PAM was superior to L-PAM alone in patients greater than or equal to 50 years of age, particularly those with greater than or equal to 4 positive nodes. The three-drug combination of L-PAM, 5-FU, and methotrexate failed to provide a benefit over and above that achieved by the L-PAM-5-FU combination in all subsets examined. The results underscore the heterogeneous response to chemotherapy demonstrated by patient subsets characterized on the basis of age and nodal status. The implications of the findings relative to the current status of adjuvant therapy are discussed.