OUTCOMES OF OXALIPLATIN- BASED ADJUVANT CHEMOTHERAPY IN HIGH-RISK STAGE II AND STAGE III COLON CANCER: A RETROSPECTIVE STUDY AT HANOI MEDICAL UNIVERSITY HOSPITAL

Objectives: To describe the clinical and clinicopathological characteristics and evaluate the efficacy and safety of oxaliplatin-based adjuvant chemotherapy in patients with high-risk stage II and stage III colon cancer treated at Hanoi Medical University Hospital. Materials and Methods: This retrospective descriptive study included 135 patients with high-risk stage II and stage III colon cancer who underwent curative resection followed by oxaliplatin-based adjuvant chemotherapy at the Oncology Center, Hanoi Medical University Hospital, between January 2020 and December 2024. Survival data were updated through March 2026. Survival outcomes were estimated using the Kaplan-Meier method. Comparisons between the two regimens were exploratory and performed using the log-rank test and a Cox regression model adjusted for disease stage. Toxicities were graded according to the CTCAE version 5.0, based on the highest grade recorded for each patient throughout chemotherapy. Results: The mean age of the patients was 56,9 ± 12,6 years (range, 14-82 years). The proportions of male and female patients were comparable. The most common tumor locations were the sigmoid colon (51,1%) and ascending colon (25,9%). Adenocarcinoma was the predominant histological subtype (87,4%), and most tumors were moderately differentiated (85,2%). High-risk stage II and stage III disease accounted for 28,9% and 71,1% of cases, respectively, with stage IIIB representing the largest subgroup (48,1%). The mFOLFOX6 regimen was used in 71,9% of cases and CAPOX in 28,1%. The estimated 1-, 2-, and 3-year DFS rates were 91.8%, 79.8%, and 76.1%, respectively (3-year DFS, 95% CI: 67.7-82.6). The corresponding OS rates were 97.8%, 91.6%, and 88.8% (3-year OS, 95% CI: 81.7-93.3). Exploratory analysis showed no evidence of a difference in OS between the two regimens. The stage-adjusted hazard ratio for CAPOX versus mFOLFOX6 was 0.79 (95% CI: 0.26-2.47; p=0.691). Most adverse events were grade 1-2, whereas grade 3-4 events were uncommon. Conclusions: Among patients receiving oxaliplatin-based adjuvant chemotherapy, the estimated 3-year DFS and OS rates were 76.1% and 88.8%, respectively. The toxicity profile was acceptable, with grade 3–4 toxicities being uncommon.