Surgery Reduces Cancer-specific Death in Elderly Right-Sided Colon Cancer: A SEER-Based Competing-Risk Analysis

Introduction Right-sided colon cancer (RCC) is common among older adults and represents a major clinical burden in this population. However, substantial competing mortality and the lack of competing-risk analyses in prior studies have obscured the cancer-specific benefit of surgery. Methods We conducted a retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) database (2010-2015), including patients aged ≥75 years with RCC. To minimize baseline imbalances, a 1:1 propensity-score–matched (PSM) cohort was constructed. Survival was assessed using Kaplan–Meier methods for overall and cancer-specific survival and competing-risk analyses for cancer-specific death (CSD) and other-cause death (OCD). Independent predictors of CSD were identified using multivariable Fine–Gray regression, and a competing-risk nomogram was developed and internally validated for individualized risk prediction. Results Among 46,932 eligible patients, 1:1 propensity-score matching with exact T and M stage matching yielded a balanced cohort of 2,892 patients (1,446 per group). In the matched cohort, surgery was associated with significantly improved overall and cancer-specific survival. Competing-risk analyses showed that the 5-year cumulative incidence of CSD was 20.4% in the surgery group versus 63.9% in the non-surgery group (Gray’s test P < 0.001), while OCD was 31.7% versus 29.6% (Gray’s test P < 0.001). In multivariable Fine–Gray regression, surgery remained the strongest independent protective factor for CSD (sHR 0.18, 95% CI 0.16–0.19; P < 0.001). Sensitivity analysis excluding T1 tumours showed that the association between surgery and improved survival remained consistent. The resulting competing-risk nomogram showed acceptable discrimination and overall calibration, and decision curve analysis suggested potential net clinical benefit across a range of thresholds. Conclusion In elderly patients with RCC, our findings are consistent with a cancer-specific survival benefit of surgery.