Effect of Adjuvant Chemotherapy on Stage II Colon Cancer: Analysis of Korean National Data

Purpose Debates exist regarding the effectiveness of adjuvant chemotherapy for stage II colon cancer. This study aimed to investigate the current status of adjuvant chemotherapy and its impact on survival for Korean stage II colon cancer patients by analyzing the National Quality Assessment data. Materials and Methods A total of 7,880 patients who underwent curative resection for stage II colon adenocarcinoma between January 2011 and December 2014 in Korea were selected randomly as evaluation subjects for the quality assessment. The factors that influenced overall survival were identified. The high-risk group was defined as having at least one of the following: perforation/obstruction, lymph node harvest less than 12, lymphovascular/perineural invasion, positive resection margin, poor differentiation, or pathologic T4 stage. Results The median follow-up period was 38 months (range, 1 to 63 months). Chemotherapy was a favorable prognostic factor for either the high-(hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.38 to 0.59; p < 0.001) or low-risk group (HR, 0.74; 95% CI, 0.61 to 0.89; p=0.002) in multivariate analysis. This was also the case in patients over 70 years of age. The hazard ratio was significantly increased as the number of involved risk factors was increased in patients who didn't receive chemotherapy. Adding oxaliplatin showed no difference in survival (HR, 1.36; 95% CI, 0.91 to 2.03; p=0.132). Conclusion Adjuvant chemotherapy can be recommended for stage II colon cancer patients, but the addition of oxaliplatin to the regimen must be selective.