Abstract
BACKGROUND: The National Comprehensive Cancer Network guidelines recommend adjuvant chemotherapy (ACT) for patients with stage II colon cancer who have undergone curative surgery when fewer than 12 lymph nodes (LNs) are retrieved. This study seeks to further examine the requirement for ACT in individuals who had 12 or more LNs harvested. AIM: To investigate if stage II colon cancer patients with 12 or more LNs retrieved benefit from ACT. METHODS: This retrospective cohort study included individuals diagnosed with stage II colon cancer who underwent surgery between 2008 and 2017 from the Surveillance, Epidemiology, and End Results (SEER) registry and a Chinese multicenter database. All patients had at least 12 LNs retrieved. The key endpoint was overall survival (OS). Cox regression analysis was performed to assess independent OS predictors. Propensity score matching controlled for confounders, and Kaplan-Meier analysis evaluated the impact of ACT on survival. RESULTS: A total of 32742 patients with stage II colon cancer from the SEER cohort and 3153 patients from the Chinese cohort were included. The average number of LNs retrieved was 20.0 (15.0, 26.0) in the SEER cohort and 18.0 (15.0, 22.0) in the Chinese cohort. No-ACT remained an independent risk factor in both cohorts (hazard ratio = 1.589, 95% confidence interval: 1.485-1.700 and hazard ratio = 1.865, 95% confidence interval: 1.465-2.375, respectively). In the SEER cohort, patients in the ACT group consistently demonstrated better 5-year OS rates both before and after propensity score matching (79.4% vs 66.1% and 79.4% vs 69.4%, both P < 0.0001). Similarly, these findings were further validated in the Chinese cohort (91.2% vs 82.1% and 90.0% vs 82.8%, both P < 0.0001). ACT improved prognosis even in T3 and grade 1/2 patients. CONCLUSION: This research, based on two large population-based cohorts, demonstrates that stage II colon cancer patients with 12 or more LNs retrieved can still benefit from ACT.