Modulation of fluorouracil by leucovorin in patients with advanced colorectal cancer: evidence in terms of response rate. Advanced Colorectal Cancer Meta-Analysis Project.

Abstract

A meta-analysis was performed on nine randomized clinical trials that compared fluorouracil (5-FU) with 5-FU plus intravenous (IV) leucovorin (LV) for the treatment of advanced colorectal cancer. The analysis was based on the most recently updated individual patient data from all trials. The end points of interest were tumor response and overall survival. Therapy with 5-FU plus LV administered either as weekly or monthly regimens showed a highly significant benefit over single-agent 5-FU in terms of tumor response rate (23% v 11%; response odds ratio (OR), 0.45; P less than 10(-7)). This increase in response did not result in a discernable improvement of overall survival (survival OR, 0.97; P = .57). The large number of patients who did not respond to treatment in both groups, and cross-overs from 5-FU alone to 5-FU plus LV are discussed as plausible explanations for the lack of a survival difference. These results confirm the advantage of 5-FU plus leucovorin over 5-FU alone in terms of objective tumor response. They also suggest that in planning future trials, tumor response should not be considered a valid surrogate end point for survival in patients with advanced colorectal cancer.