The survival benefit of adjuvant radiotherapy for pathological T4N2M0 colon cancer in the Modern Chemotherapy Era: evidence from the SEER database 2004-2015.

Neoadjuvant chemoradiotherapy has been established as the standard treatment for patients with locally advanced rectal cancer. However, the role of radiotherapy (RT) has not been fully confirmed in advanced colon cancer (LACC). We postulated that patients with pathological T4N2 locally advanced colon cancer would benefit more from RT. 6715 pT4N2M0 colon cancer patients were included in the Surveillance, Epidemiology, and End Results (SEER) database. The primary endpoints were 5-year overall survival (OS) and cancer-specific survival (CSS). Propensity score matching (PSM) with Kaplan-Meier and Cox proportional hazards' models was performed to estimate prognosis. Before PSM, patients underwent RT had better OS and CSS as compared to patients did not receive RT (OS: 40.1% vs 27.6%,  < .001; CSS: 49.6% vs 41.1%,  = .002). After PSM, 239 matched pairs were formed for further analysis. RT group also presented significantly improved prognosis (OS: 40.1% vs 25.7%,  = .008; CSS: 49.6% vs 38.2%,  = .042). Multivariable Cox regression analysis showed that RT was a protective factor [OS：Hazard ratio (HR) =0.677, 95% Confidence interval (CI): 0.532-0.862,  = .002; CSS: HR = 0.708, 95% CI: 0.533-0.941,  = .018]. For pT4N2M0 colon cancer patients, the addition of RT seems to confer survival benefit as compared to patients who did not receive RT.