Purpose: Irinotecan (CPT11) at 180mg/m(2) with LV5FU2 for metastatic colorectal cancer (MCRC) has response rates (RRs) of 56 and 4% as first-and second-line treatments, respectively [1-2], and higher doses of CPT11 result in higher RRs. The present cohort analysis aimed to evaluate the effect of increasing doses of this combination treatment in clinical practice. Methods: Chemo-naive and pretreated patients with MCRC received CPT11 and LV5FU2 (5FU 48-h CI 2400mg/m(2), D1 bolus leucovorin 200mg/m(2)), followed by 5FU 400mg/m(2) (cycles d1-d15). CPT11 dose was increased by 20mg/m(2) at each cycle, from 180mg/m(2) up to 260mg/m(2), unless grade 3 toxicities other than alopecia arose. Results: Between March 2002 and September 2005, 46 patients were recruited (median age: 62.3 years). A total of 512 cycles of chemotherapy were administered (median: 9 cycles/patient; range: 3-41). Median follow-up was 16.2 months. Altogether, 27 patients had received prior chemotherapy: 24 with an oxaliplatin-based regimen; seven with CPT11; and five with LV5FU2 or oral 5FU. Doses of 260mg/m(2) were used in 17 patients, 240mg/m(2) in seven, 220mg/m(2) in six and 200mg/m(2) in five, while 11 remained at 180mg/m(2); 121 cycles used 260mg/m(2) (24%), with 76 cycles at 240mg/m(2) (14%), 78 cycles at 220mg/m(2) and 58 cycles at 200mg/m(2). The objective response (OR) was 40%, with stable disease (SD) in 45% and disease progression (DP) in 11%. In the first-line therapy group, partial/complete responses were 55%, with SD in 30% and DP in 15%. In pretreated patients, OR was 30.5%, SD was 58.5% and DP was 11%. Nine patients (20%) had a therapeutic break (median: 5.1 months; range: 3-10). Overall median survival was 17 months, with 16.5 months in pretreated patients and 19.6 months in the first-line group. Toxicity grades 3-4 and overall incidence per cycle were: neutropenia, 3-22%; diarrhea, 4-22%; vomiting, 2-20%; alopecia, 20-26%; anemia, 0.2-2%; thrombocytopenia, 0-0%; and mucositis, 0.4-2.2%. Conclusion: The toxicity of high-dose CPT11 + LV5FU2 chemotherapy was well tolerated when the dose was progressively increased according to individual tolerability, with 37% of patients receiving CPT11 at 260mg/m(2). Progression-free survival (PFS) increased with higher doses of CPT11. In the chemo-naive and pretreated subgroups, the median PFS was 10.9 and 8.8 months, respectively (P = 0.698, NS). Optimization of CPT11 doses in pretreated patients appears to pave the way for new treatment options. (C) 2010 Elsevier Masson SAS. All rights reserved.