Modified irinotecan plus bolus 5-fluorouracil/L-leucovorin for metastatic colorectal cancer at a single institution in Japan

Background The modified irinotecan plus bolus 5-fluorouracil/L-leucovorin (IFL) regimen (irinotecan plus bolus 5-fluorouracil/L-leucovorin) used to be one of the standard treatments for metastatic colorectal cancer until approval of oxaliplatin in Japan. We evaluated the efficacy of modified IFL therapy for Japanese patients. Methods Forty-seven patients with metastatic colorectal cancer received irinotecan (100 mg/m²) and bolus 5-fluorouracil (500 mg/m²) plus L-leucovorin (10 mg/m²) on days 1 and 8 every 3 weeks until progression or unmanageable toxicity occurred. The data on toxicity and tumor response were analyzed retrospectively. Results All patients discontinued modified IFL therapy due to cancer progression, except for one patient who developed severe liver dysfunction. The overall response rate was 25%. The median progression-free survival time (PFS) was 6.1 months. The median overall survival time (OS) was 17.4 months for all patients, 28.8 months for patients receiving subsequent oxaliplatin therapy, and 8.9 months for patients without oxaliplatin (P = 0.0031). According to multivariate analysis results, good performance status, a normal white cell count, and absence of local recurrence were associated with a better PFS. Tumor response was a good prognostic factor for both PFS and OS. Gastrointestinal symptoms were the most common toxicities, including grade 3 diarrhea (8%) and grade 3 anorexia (10%). Grade 4 neutropenia occurred in 6% of patients. No other drug-related severe adverse events or deaths were observed. Conclusions Modified IFL therapy is an effective and well-tolerated regimen for Japanese patients with metastatic colorectal cancer. Modified IFL therapy combined with biological agents might remain an option for some patients who refuse a central venous catheter.