Randomized trial of adjuvant therapy in colon carcinoma: 10-year results of NSABP protocol C-01

Background: The National Surgical Adjuvant Breast and Bowel Project C-01 trial reported in 1988 that, for patients with adenocarcinoma of the colon, compared with surgery alone, 1) postoperative chemotherapy with 1-(2-chloroethyl)-3-(4-trans-methylcyclohexyl)-1-nitrosourea (i.e., MeCCNU or semustine), vincristine, and 5-fluorouracil was associated with better 5-year disease-free and overall survival and 2) postoperative immunotherapy with bacillus Calmette-Guerin was associated with better 5-year overall, but not disease-free, survival. We now provide a 10-year update of this trial. Methods: Between November 11, 1977, and February 28, 1983, 1166 patients with resected Dukes' stage B and C adenocarcinoma of the colon were stratified by Dukes' stage, sex, and age (<65 years or greater than or equal to65 years) and then randomly assigned to receive no further treatment (surgery alone; 394 patients), adjuvant chemotherapy (379 patients), or adjuvant immunotherapy (393 patients). Those eligible for follow-up included 375 (95.2%) patients in the surgery-alone group, 349 (92.1%) patients in the adjuvant-chemotherapy group, and 372 (94.7%) patients in the adjuvant-immunotherapy group. All statistical tests were two-sided. Results: No difference was observed between patients in the chemotherapy group and those in the surgery-alone group in 10-year disease-free survival (hazard ratio [HR] = 1.14, 95% confidence interval [CI] = 0.94 to 1.39; P = .17) or overall survival (HR = 1.12, 95% CI = 0.91 to 1.38; P = .27). Immunotherapy did not appear to prevent tumor relapse after 10 years (for surgery alone versus immunotherapy, relative risk [RR] = 0.99, 95% CI = 0.78 to 1.25; P = .93) but had a beneficial effect on 10-year overall survival (for surgery alone versus immunotherapy, RR = 1.27, 95% CI = 1.03 to 1.56; P = .02) that apparently results from a reduction in deaths associated with comorbidities in the immunotherapy group. Conclusion: The disease-free and overall survival benefit associated with chemotherapy in this patient population is of limited duration, disappearing after 10 years.