Disparities in survival for right-sided vs. left-sided colon cancers in young patients: a study based on the Surveillance, Epidemiology, and End Results database (1990-2014).

Purpose: To investigate whether young patients exhibit different characteristics and survival according to tumor location and stage using data from the Surveillance, Epidemiology, and End Results (SEER) database. Patients and methods: Young patients (20-49 years old) with stage I-III colon cancers were identified from the SEER program from 1990 to 2014. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to analyze the data. Subset analyses were also done among different age and stage subgroups. Results: Of 8197 patients, 3709 (45.2%) had right-sided colon cancers (RCCs). Patients with RCCs were more likely to be male, to be younger, and to have more poorly differentiated and more advanced tumors. The Kaplan-Meier survival curves and univariate survival models revealed that left-sided colon cancers (LCCs) had lower mortality for all stages combined and stage III, but higher mortality for stage II, compared with right-sided tumors. However, multivariate Cox regression models showed no significant survival differences by location for all patients (adjusted hazard ratio [HR], 0.95; 95% confidence interval [CI], 0.86-1.05; P=0.34) or for stage I (adjusted HR, 1.47; 95% CI, 0.82-2.63; P=0.20). Stage II left-sided cancers had higher mortality (adjusted HR, 1.24; 95% CI, 1.00-1.54; P=0.048), whereas stage III left-sided cancers had lower mortality (adjusted HR, 0.86; 95% CI, 0.77-0.97; P=0.01). For 20- to 39-year-old patients, a significant difference was only found in stage II disease, with a higher mortality for left-sided tumors (adjusted HR, 1.82; 95% CI, 1.12-2.97; P=0.02). However, for 40-to 49-year-old patients, a significant difference was only found in stage III disease, with a lower mortality for left-sided tumors (adjusted HR, 0.83; 95% CI, 0.72-0.95; P=0.008). Conclusion: In patients younger than 50 years, there were no significant differences in mortality between RCCs and LCCs for all stages combined after adjusting for multiple clinicopathological features. However, RCCs had lower mortality in stage II (especially in 20-to 39-year-old patients) and higher mortality in stage III (especially in 40-to 49-year-old patients).