Comparison of two novel staging systems with the TNM system in predicting stage III colon cancer survival

Background and ObjectivesAdaptations of the TNM staging system that incorporate the Lymph Node Ratio (LNR) have been proposed for stage III colon cancer. This study compared the concordance of two novel staging systems and the TNM system with observed survival outcomes in stage III patients. MethodsA review of patients who underwent surgery for stage III colon cancer between January 2002 and April 2015 at a tertiary care centre was performed. The Kaplan-Meier method was used to estimate the 5-year overall (OS) and disease free survival (DFS) rates, and the concordance probability was calculated to evaluate the discriminatory power of the staging systems. ResultsTwo hundred and sixty-one patients were identified. For TNM stages IIIA, IIIB, and IIIC, 5-year OS was 83.4%, 67.6%, and 38.3%, respectively (P<0.001). All three staging systems were independently predictive of OS and DFS (P<0.001). However, the novel staging system by Sugimoto et al(18) was the most favourable prognostic tool, with a concordance of 0.646 for DFS and 0.659 for OS. ConclusionsThe novel staging system by Sugimoto et al(18) was superior to the TNM system. Incorporating LNR into staging models for node positive colon cancers may improve survival information available to patients and potentially aid treatment decisions.