Irinotecan or oxaliplatin combined with leucovorin and 5-fluorouracil as first-line treatment in advanced colorectal cancer: a multicenter, randomized, phase II study.
BACKGROUND
Irinotecan (IRI) and oxaliplatin (OXA) are effective in the treatment of colorectal cancer. Previously untreated patients with advanced colorectal carcinoma (CRC) were randomly assigned to receive IRI plus leucovorin (LV)/5-fluorouracil (5-FU), or OXA plus LV/5-FU in order to compare the response rates, time-to-tumor progression, overall survival rates, and toxicity profiles of these two agents.


MATERIALS AND METHODS
From January 1999 to February 2002, 295 patients were randomized to receive either IRI/LV/5-FU or OXA/LV/5-FU. The treatment schedules consisted of weekly IRI 70 mg/m(2) or OXA 45 mg/m(2) plus LV 200 mg/m(2) followed immediately by intravenous bolus 5-FU 450 mg/m(2) for 6 weeks, followed by a 2-week rest period. Treatment was continued for up to four cycles or until disease progression, unacceptable toxicity or patient refusal.


RESULTS
There were no significant differences between the study arms in the overall response rate (33% with IRI/LV/5-FU versus 32% with OXA/LV/5-FU based on responses demonstrated on a single evaluation; 23% with IRI/LV/5-FU versus 22.3% with OXA/LV/5-FU based on responses confirmed according to WHO criteria) median time to progression (8.9 versus 7.6 months), and median overall survival (17.6 versus 17.4 months). Toxicity profiles (grades 3 and 4) were similar in the IRI and OXA arms (diarrhea 12.3% and 9.8%, neutropenia 8.2% and 4.9%, and febrile neutropenia 1.4% and 1.4%, respectively), with the exception of grade 3 sensory neuropathy, which almost exclusively occurred in the OXA arm (0% versus 5.6%; P=0.003, Fisher's exact test).


CONCLUSION
The IRI/LV/5-FU and OXA/LV/5-FU regimens demonstrated equally substantial efficacies and manageable toxicity profiles in the first-line treatment of patients with advanced CRC. However, IRI/LV/5-FU may be the preferable regimen to avoid significant neurotoxicity associated with OXA-LV/5-FU.