Oxaliplatin As Adjuvant Therapy for Colon Cancer: Updated Results of NSABP C-07 Trial, Including Survival and Subset Analyses

Abstract

Purpose: The National Surgical Adjuvant Breast and Bowel Project (NSABP) C-07 trial demonstrated that the addition of oxaliplatin to fluorouracil plus leucovorin (FULV) improved disease-free survival (DFS) in patients with stage II or III colon cancer. This analysis is the first publication of overall survival (OS) for the NSABP C-07 study. We updated DFS and examined both end points in clinically relevant patient subsets. Patients and Methods: Other studies have identified patients age 70 or older and those with stage II disease as patient subsets in which oxaliplatin may not be effective. We investigated toxicity as a driver of divergent outcomes in these subsets. Results: In all, 2,409 eligible patients with follow-up were randomly assigned to either FULV (FU 500 mg/m 2 by intravenous [IV] bolus weekly for 6 weeks; leucovorin 500 mg/m 2 IV weekly for 6 weeks of each 8-week cycle for three cycles) or FLOX (FULV plus oxaliplatin 85 mg/m 2 IV on days 1, 15, and 29 of each cycle). With 8 years median follow-up, OS was similar between treatment groups (hazard ratio [HR], 0.88; 95% CI, 0.75 to 1.02; P = .08). FLOX remained superior for DFS (HR, 0.82; 95% CI, 0.72 to 0.93; P = .002). The effect of oxaliplatin on OS did not differ by stage of disease (interaction P = .38 for OS; interaction P = 0.37 for DFS) but did vary by age for OS (younger than age 70 v 70+ interaction P = .039). There was a similar trend for DFS (interaction P = .073). Oxaliplatin significantly improved OS in patients younger than age 70 (HR, 0.80; 95% CI, 0.68 to 0.95; P = .013), but no positive effect was evident in older patients. Conclusion: Overall, the addition of oxaliplatin to FULV has not been proven to extend OS in this trial, but the DFS effect remained strong. Unplanned subset analyses suggest a significant OS effect of oxaliplatin in patients younger than age 70.