Background In a randomized trial with a median follow-up of 18.4 months, 6 months of induction chemotherapy with a three-drug regimen comprising 5-fluorouracil (by continuous infusion)-leucovorin, irinotecan, and oxaliplatin (FOLFOXIRI) demonstrated statistically significant improvements in response rate, radical surgical resection of metastases, progression-free survival, and overall survival compared with 6 months of induction chemotherapy with fluorouracil-leucovorin and irinotecan (FOLFIRI). Methods From November 14, 2001, to April 22, 2005, we enrolled 244 patients with metastatic colorectal cancer. To evaluate if the superiority of FOLFOXIRI is maintained in the long term, we updated the overall and progression-free survival data to include events that occurred up to February 12, 2009, with a median follow-up of 60.6 months. We performed a subgroup and a risk-stratified analysis to examine whether outcomes differed in specific patient subgroups, and we analyzed the results of treatment after progression. Survival curves were estimated by the Kaplan-Meier method. Multivariable Cox regression models were fit to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). All statistical tests were two-sided. Results FOLFOXIRI demonstrated statistically significant improvements in median progression-free survival (9.8 vs 6.8 months, HR for progression = 0.59, 95% CI = 0.45 to 0.76, P