Five-year results of a randomized controlled trial of adjuvant chemotherapy for curatively resected colorectal carcinoma. The Colorectal Cancer Chemotherapy Study Group of Japan

Abstract

In order to evaluate the significance of postoperative adjuvant chemotherapy for colorectal carcinoma, the Colorectal Cancer Chemotherapy Study Group, from 140 leading hospitals in Japan, conducted a prospective, randomized, controlled trial on patients who had undergone curative resections for colorectal carcinomas during the period from February 1984, to December 1985. The regimens for colon cancer were, Arm I: mitomycin C [intraoperative portal vein bolus (12 mg/m2) + postoperative, twice weekly and then three times bimonthly for six months intermittent i.v. bolus (6 mg/m2)] + 5-fluorouracil (5-FU) 200 mg/body/day p.o. for six months; Arm II: postoperative twice weekly and then three times bimonthly intermittent i.v. bolus mitomycin C (6 mg/m2) for six months + 5-FU 200 mg/body/day p.o. for six months; Arm III: surgery alone. The regimens for rectal cancer were, Arm IV: same as Arm I, with superior rectal artery infusion of the same mitomycin C dose instead of portal vein infusion; Arm V: same as Arm II; Arm VI: same as Arm III. Of 2001 collected cases, 1805 eligible cases (899 colon cancers and 906 rectal cancers) were analyzed. Significant differences in five-year survival rates were found between Arms IV and V and Arm VI [Arm IV: 70.7% (95% confidence interval (C.I.): 65.6-75.8%), P = 0.004 vs Arm V: 73.6% (68.5-78.7%), P = 0.000 vs Arm VI (control): 60.2% (54.5-65.9%)]. No significant difference in overall survival rate was found in the colon cancer patients [Arm I: 80.4% (75.7-85.1%), not significant (N.S.) vs Arm II: 82.1% (77.8-86.4%), N.S. vs Arm III (control): 79.5% (74.6-84.4%)]. When stratified into Dukes classes, however, Dukes C patients in Arm II showed a significantly improved survival rate compared with that of those in Arm III [Arm I: 72.6% (64.8-80.4%), N.S. vs Arm II: 75.0% (67.9-82.1%), P = 0.012 vs Arm III (control): 61.0% (51.4-70.6%)]. We conclude the adjuvant use of long term oral 5-FU and intermittent mitomycin C (i.v.) to improve the survival rate of patients with curatively resected rectal cancer. Further comparative study is, however, recommended to confirm the effectiveness of 5-FU alone and the combination of 5-FU and mitomycin C. Regional chemotherapy made no contribution to reducing an hepatic recurrence of colon cancer or a local recurrence of rectal cancer.