Utilization and impact of adjuvant chemotherapy among patients with resected stage II colon cancer: a multi-institutional analysis

Background: The use of chemotherapy among patients with stage II colon cancer is controversial. We aimed to define the utilization and factors associated with the receipt of chemotherapy and the impact of chemotherapy on long-term prognosis among a large, multiinstitutional cohort of patients. Materials and methods: We identified 876 patients who underwent resection for stage II colon cancer between 2004 and 2013 at one of seven participating institutions. Overall survival (OS) and recurrence-free survival (RFS) time was calculated from the date of the index procedure to the date of death. Results: A total of 163 patients (18.6%) received adjuvant chemotherapy and this utilization decreased over time (P = 0.003). Younger age (P < 0.001), margin positivity (odds ratio [OR], 12.16; 95% confidence interval [CI]: 2.57-57.52; P = 0.002), and the presence of perineural invasion (OR, 1.24; 95% CI: 1.07-1.44; P = 0.005) increased the likelihood of receiving chemotherapy. Receipt of chemotherapy was associated with improved median OS and RFS. After controlling for all factors, the addition of oxaliplatin to 5-fluorouracil did not affect survival, and there was no difference in OS (hazard ratio [HR], 0.74; 95% CI: 0.27-2.06; P = 0.57) or RFS (HR, 0.71; 95% CI: 0.32-1.58; P = 0.88) with adjuvant treatment, including for patients with high-risk features (OS-HR, 0.63; 95% CI: 0.33-1.19; P = 0.15; RFS-HR, 0.77; 95% CI: 0.32-1.86; P = 0.56). Conclusions: The utilization of chemotherapy has declined over time after resection for stage II colon cancer. Chemotherapy was not independently associated with improved OS or RFS in this study group, including in patients with high-risk features. Future prospective studies should strive to identify the subset of stage II colon cancer patients that will benefit the most from the addition of adjuvant chemotherapy. (C) 2017 Elsevier Inc. All rights reserved.