Real-world tolerance and outcomes of oxaliplatin-based adjuvant chemotherapy for stage III colon cancer-Does dose intensity matter?

Introduction: Fluoropyrimidine and oxaliplatin-based adjuvant chemotherapy delivered as 5-fluorouracil, leucovorin and oxaliplatin (FOLFOX), or capecitabine and oxaliplatin (CAPOX) is the standard of care for resected stage III colon cancer. Without randomized trial data, we compared real-world dose intensity, survival outcomes, and tolerability of these regimens.

Methods: Records of patients treated with FOLFOX or CAPOX in the adjuvant setting for stage III colon cancer across four institutions in Sydney during 2006-2016 were reviewed. The relative dose intensity (RDI) of fluoropyrimidine and oxaliplatin of each regimen, disease-free survival (DFS), overall survival (OS), and incidence of grade ≥2 toxicities were compared.

Results: Characteristics of patients receiving FOLFOX (n = 195) and CAPOX (n = 62) were evenly matched. FOLFOX patients had a higher mean RDI for both fluoropyrimidine (85% vs. 78%, p < 0.01) and oxaliplatin (72% vs. 66%, p = 0.06). In spite of a lower RDI, CAPOX patients trended toward a better 5-year DFS (84% vs. 78%, HR = 0.53, p = 0.068) and similar OS (89% vs. 89%, HR = 0.53, p = 0.21) compared to the FOLFOX group. This difference was most pronounced in the high-risk (T4 or N2) group where 5-year DFS was 78% versus 67% (HR = 0.41, p = 0.042). Patients receiving CAPOX experienced more grade ≥2 diarrhea (p = 0.017) and hand-foot syndrome (p < 0.001) but not peripheral neuropathy or myelosuppression.

Conclusion: In a real-world setting, patients who received CAPOX had similar OS rates when compared to those receiving FOLFOX in the adjuvant setting in spite of lower RDI. In the high-risk population, CAPOX appears to demonstrate a superior 5-year DFS over FOLFOX.