This multicenter adjuvant phase III trial evaluated the addition of irinotecan to LV5FU2 in colon cancer patients at high risk of relapse.

A total of 400 patients with histologically proven primary colon cancer with postoperative N1 detected by occlusion/perforation or N2 were randomised to: A-LV5FU2 [leucovorin 200 mg/m(2), 2-h infusion, 5-fluorouracil (5-FU) 400 mg/m(2) bolus, 600 mg/m(2) 22-h continuous infusion, days 1 and 2] or B-LV5FU2 + IRI (irinotecan 180 mg/m(2) 90-min infusion day 1 + LV5FU2) fortnightly for 12 cycles. Primary end point was disease-free survival (DFS).

Median follow-up was 63 months. Significantly more T4 tumours and 15 or more positive lymph nodes were observed in arm B. 5-FU relative dose intensity (RDI) was >0.80 for 94% and 77% in arms A and B, respectively (P < 0.001). Irinotecan RDI was >0.80 for 70% patients. There were more grades 3 and 4 neutropenia in arm B (4% versus 28%, P < 0.001). The 3-year DFS was 60% [95% confidence interval (CI) 53% to 66%] and 51% (95% CI 44% to 58) in arms A and B, respectively. No difference was observed [hazard ratio (HR) = 1.12, 95% CI 0.85-1.47, P = 0.42] even when adjusted for prognostic factors (adjusted HR = 0.98, 95% CI 0.74-1.31, P = 0.92). The 5-year overall survival (OS) was 67% (95% CI 59% to 73%) and 61% (95% CI 53% to 67%) in arms A and B, respectively.

Adjuvant LV5FU2 + IRI compared with LV5FU2 alone in patients at high risk of relapse showed no improvement in DFS and OS.