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.