Adjuvant chemotherapy in the treatment of colon cancer: randomized multicenter trial of the Italian National Intergroup of Adjuvant Chemotherapy in Colon Cancer (INTACC).

Background: To determine whether the addition of leucovorin to the combination 5-fluorouracil plus levamisole prolongs disease-free survival and overall survival in patients with radically resected colon cancer (Dukes' B(2-3) and C).

Patients And Methods: Patients (1703) were accrued between March 1992 and February 1995 in a large-scale clinical trial within five Italian cooperative groups. After stratification for center, patients were randomized as follows: arm A, 5-fluorouracil [450 mg/m(2) intravenous (i.v.) bolus on days 1-5] and levamisole (150 mg orally for 3 days, every 14 days for 6 months) versus arm B, 6-S-leucovorin (100 mg/m(2) i.v. bolus on days 1-5) followed by 5-fluorouracil (370 mg/m(2) i.v. bolus on days 1-5), plus levamisole (as arm A), every 4 weeks for six cycles.

Results: After a median follow-up of 6.4 years no significant difference was seen for either disease-free survival (58% versus 60%, not significant) or 5-year overall survival (68% versus 71%, not significant), respectively. Gastrointestinal toxicity (World Health Organization grade 3/4) was more frequent in arm B (8% versus 18%, not significant).

Conclusions: In this trial the schedules used showed no statistically significant differences in terms of disease-free survival or overall survival in the treatment of colorectal cancer.