Randomized trial of observation versus adjuvant therapy with cyclophosphamide, fluorouracil, prednisone with or without tamoxifen following mastectomy in postmenopausal women with node-positive breast cancer

Following mastectomy for node-positive breast cancer, 261 postmenopausal women were randomized to observation or adjuvant treatment with cyclophosphamide, fluorouracil, prednisone (CFP) alone or combined with tamoxifen (T). Doses used were: C, 150 mg/m² intravenously (IV) days 1 to 5; F, 300 mg/m² IV days 1 to 5; P, 10 mg by mouth 3 times daily on days 1 to 7; and T, 10 mg by mouth 2 times daily. A total of ten courses of treatment, administered every 6 weeks, was planned and T was stopped 6 weeks after the last course of CFP. Two hundred thirty-four patients were fully eligible and evaluable. With a median observation time slightly in excess of 5 years, the proportion of recurrences on each arm were: CFP, 29 of 75 (39%); CFPT, 29 of 71 (41%); and observation, 50 of 88 (57%). Relapse-free survival distributions for both CFP and CFPT were superior to observation (both two-sided P = .01). Considering prognostic factors in covariate analysis revealed two-sided P = .0006 for CFP v observation and P = .0003 for CFPT v observation. No substantial difference was identified between CFP and CFPT. Survival data are not yet mature with 31% dead; and, although slight separations of the curves exist in favor of the treatment arms, no significant differences in survival have been seen. Both adjuvant therapy programs are well tolerated and there were no treatment-related deaths. Further maturation of the data is required to determine if the advantages in relapse-free survival will be translated into any overall survival benefit which must be considered the goal of primary interest.