Effect of Adjuvant Chemotherapy on Elderly Stage II High-Risk Colorectal Cancer Patients

PURPOSE: Adjuvant chemotherapy (AC) is recommended for patients with stage II colorectal cancer with adverse features. However, the effect of adjuvant treatment in elderly patients with high-risk stage II colorectal cancer remains controversial. This study aimed to investigate the oncologic outcomes in elderly high-risk stage II colorectal cancer patients who underwent curative resection with or without AC. METHODS: Patients aged over 70 years having stage II colorectal adenocarcinoma with at least 1 adverse feature who underwent radical surgery between 2008 and 2017 at a single center were included. We compared recurrence-free survival (RFS) and overall survival (OS) between patients who received more than 80% of the planned AC cycle (the AC+ group) and those who did not receive it (the AC− group). RESULTS: The AC+ and AC– group contained 46 patients and 50 patients, respectively. The log-rank test revealed no significant intergroup differences in RFS (P=0.083) and OS (P=0.122). In the subgroup of 27 patients with more than 2 adverse features, the AC+ group (n=16) showed better RFS (P=0.006) and OS (P=0.025) than the AC− group. In this subgroup, AC was the only significant factor affecting RFS in the multivariate analysis (P=0.023). AC was significantly associated with OS (P=0.033) in the univariate analysis, but not in the multivariate analysis (P=0.332). CONCLUSION: Among elderly patients with stage II high-risk colorectal cancer, the AC+ group did not show better RFS or OS than the AC− group. However, selected patients with more than 2 adverse features might benefit from AC.