- Rothenberg et al called for caution in the palliative use of irinotecan, 5-fluorouracil (5-FU) bolus and leucovorin (IFL schedule), because of early treatment related deaths in C89803 and N9741 studies. The objective of our multicenter phase II study was to evaluate the efficacy and safety of the combination of 5-FU bolus, folinic acid (FA) and irinotecan as first-line chemotherapy for metastatic colorectal cancer. From December 1999 to June 2002 138 patients (pts) were treated. The chemotherapy regimen was as follows: irinotecan 125 mg/m2 i.v. over 90 min and 5-FU 500 mg/m2 preceded by FA 20 mg/m2, both given by bolus, weekly, for 4 weeks every 6 weeks. Treatment continued until disease progression or unacceptable toxicity. Total number of administered cycles was 404. Average dose intensity was 75%. 47 out of 131 evaluable pts achieved a complete (n = 6) or partial (n = 41) response, leading to an overall response rate (RR) of 36% [95% confidence interval (CI) 24% to 48%], stable disease was registered in 50 (38%). The estimated median time to progression and survival were 6.5 months (95% CI 5.2-9.4) and 16.6 months (95% CI 15.1-19.3) respectively. Two-year survival was 35%. Toxicity was well manageable. In 18 (13.8%) pts the chemotherapy was stopped because of toxicity. Treatment related death was not observed. Close clinical monitoring, early recognition of toxicity, immediate therapeutic intervention are recommended for pts receiving IFL. In our experience this regimen has manageable toxicity and appropriate level of dose intensity and seems to be a good option for first-line therapy in metastatic colorectal cancer.