Effect of adjuvant capecitabine or fluorouracil, with or without oxaliplatin, on survival outcomes in stage III colon cancer and the effect of oxaliplatin on post-relapse survival: a pooled analysis of individual patient data from four randomised controlled trials

Summary Background Oxaliplatin-based adjuvant therapy is the standard of care for stage III colon cancer. Adjuvant capecitabine with or without oxaliplatin versus leucovorin and fluorouracil with or without oxaliplatin has not been directly compared; therefore, we aimed to analyse the efficacy and safety of these treatments using individual patient data pooled from four randomised controlled trials. We also assessed post-relapse survival, which has been postulated to be worse in patients receiving adjuvant oxaliplatin. Methods Patients with resected stage III colon cancer who were 18 years of age or older, with an Eastern Cooperative Oncology Group performance status of 0 or 1, from four randomised controlled trials (NSABP C-08, XELOXA, X-ACT, and AVANT; 8734 patients in total) were pooled and analysed. The treatment regimens included in our analyses were: XELOX (oxaliplatin and capecitabine); leucovorin and fluorouracil; capecitabine; FOLFOX-4 (leucovorin, fluorouracil, and oxaliplatin); and modified FOLFOX-6 (mFOLFOX-6). Disease-free survival was the primary endpoint for all trials that supplied patients for this analysis. Here, we compared disease-free, relapse-free, and overall survival between the patient groups who received capecitabine with or without oxaliplatin and those who received leucovorin and fluorouracil with or without oxaliplatin. Post-relapse survival was compared between the combined XELOX and FOLFOX groups, and the leucovorin and fluorouracil groups. Post-relapse survival was also compared between the capecitabine with or without oxaliplatin and leucovorin and fluorouracil with or without oxaliplatin groups. Findings Disease-free survival did not differ significantly between patients who received leucovorin and fluorouracil versus those who received capecitabine in adjusted analyses (hazard ratio [HR] 1·02 [0·93–1·11; p=0·72]) or in unadjusted analyses (HR 1·01 [95% CI 0·92–1·10; p=0·86]). Relapse-free survival was similar (adjusted HR 1·02 [0·93–1·12; p=0·72] and unadjusted HR 1·01 [95% CI 0·92–1·11; p=0·86]), as was overall survival (adjusted HR 1·04 [95% CI 0·93–1·15; p=0·50] and unadjusted HR 1·02 [0·92–1·14]; p=0·65). For overall survival, a significant interaction between oxaliplatin and fluoropyrimidine was recorded in the multiple Cox regression analysis (p=0·014). Post-relapse survival was similar in adjusted (p=0·23) and unadjusted analyses (p=0·33) for the comparison of XELOX or FOLFOX versus leucovorin and fluorouracil, and