Analysis of oxaliplatin reintroduction in patients with advanced colorectal cancer (CRC) treated with FOLFOX4 or FOLFOX7 in the optimox study

Abstract

Background: In the OPTIMOX1 study, previously untreated patients, (pts) with advanced CRC were randomized to either FOLFOX4 every 2 wks until progressio (arm A), or FOLFOX7 (arm B). There was no difference between arms in response rate, progression-free survival, and overall survival (OS)[Tournigand, JCO 2006;24:394]. The effect of oxaliplatin reintroduction on survival was inconclusive as a significant number of pts received oxaliplatin in both arms after being taken off the study. This retrospective analysis evaluated the effect of oxaliplatin reintroduction on OS. Methods: The % of pts with oxaliplatin reintroducion was calculated in each center regardless of treatment arm, number of pts, or whether reintroduction was per protocol. A Cox model was used to analyze impact of oxaliplatin reintroduction on survival, after adjustment for all baseline covariates, and using random effects to account for the fact that % pts with oxilaplatin reintroduction was estimated in each center. Centers were grouped into 4 reintroduction classes according to o% pts with oxaliplatin reintroduction (0, 1–20, 21–40, and >40). The hazard ratio (HR; adjusted for all baseline covariates) was calculated for each reintroduction class. Results: After adjustment for all other factors,% pts with oxaliplatin reintroduction had a highly significant impact on survival (p<0.001). Reintroduction class also had a significant impact on survival, after adjustment for all other factors (p=0.02; Table below). Median survival increased from 15 months in the 0% to 23 months in the >40% reintroduction class.