Effect of Age on Survival Outcome in Operated and Non-Operated Patients with Colon Cancer: A Population-Based Study

Objective To know the effect of age on survival outcome in operated and non-operated patients with colon cancer. Methods From the Surveillance, Epidemiology, and End Results database, we identified 123,356 patients with colon cancer who were diagnosed between 1996 and 2005, grouped them as older or younger than 40 years and analyzed their 5-year cancer-specific survival (CSS) data, along with some risk factors, using Kaplan-Meier methods and multivariable Cox regression models. Results The younger group had significantly higher pathological grades (P<0.001), more mucinous and signet-ring histology (P<0.001), advanced AJCC stage (P<0.001), and were more likely to undergo surgery (P<0.001). For surgically treated patients, age did not significantly affect 5-year CSS (younger: 66.7%; older: 67.3%; P = 0.86). Further analysis showed that age was an independent prognostic factor in stage I-IV disease (stage I: P = 0.001; P<0.001 for stages II-IV, in both uni- and multivariate analyses), but not for patients with unknown disease stage (P = 0.52). For non-surgically treated patients, age significantly affected 5-year CSS (younger: 16.2%; older: 12.9%; P<0.001) in univariate analysis; and was an independent prognostic factor (P<0.001) in multivariate analysis. Conclusion The CSS rate for younger CC patients was at least as high as for older patients, although they presented with higher proportions of unfavorable factors and more advanced disease.