NSABP trials of adjuvant chemotherapy for breast cancer. A further look at the evidence

Abstract

Two decades ago the National Surgical Adjuvant Breast Project (NSABP) began to test the hypothesis that adjuvant chemotherapy would influence favorably the postsurgical survival rates of women with breast cancer. Although the use of phenylalanine mustard (melphalan or (L-PAM) has been supplemented by other agents, the thrust to recommend adjuvant chemotherapy as standard treatment was created by an L-PAM series of five trials using L-PAM or L-PAM plus fluorouracil. Only the first trial, B-05, contained an untreated group. The main treated groups in these five trials are similar to each other in survival probabilities, and the main untreated group in B-05 is not different in survival than the combined results of these five trials. There were a total of nine comparison in each study-and in B-05 the subgroup of treated women 49 years or younger with one to three positive node was found to be different than the untreated group. Four subsequent subgroups of women who were 49 years or younger with one to three positive nodes are not similar in survival despite the fact that they were developed from similar main groups that had similar treatment. The initial treated subgroup in B-05 had a survival outcome that was never again achieved in the subsequent four studies. The untreated subgroup in B-05 was not different than three of the four subsequently treated subgroups. The NSABP now has evidence that denies the conclusion that adjuvant chemotherapy prolongs survival in premenopausal node-positive women. Recommendations that adjuvant chemotherapy become standard treatment for premenopausal node-positive women should be seriously reconsidered and probably withdrawn.