Heterogeneous survival between stage IIA and stage IIIA colon cancer when different numbers of lymph nodes are harvested

BackgroundWe aim to compare the prognosis between patients with stage IIA and stage IIIA colon cancer. MethodsWe analysed patients with stage IIA or stage IIIA colon cancer based on data from the US Surveillance, Epidemiology, and End Results (SEER) database. Survival data were generated as Kaplan-Meier curves and were compared by log-rank tests. A multivariate Cox proportional hazards model was used to analyze the risk factors. ResultsIn total, 43379 patients (38784 stage IIA and 4595 stage IIIA) were included from the SEER database. A Kaplan-Meier analysis showed no significant difference between patients with stage IIA and IIIA colon cancer (P=0.547). In the subgroup of patients with number of lymph nodes harvested (LNH) 12, a multivariate analysis showed that compared with stage IIA patients, stage IIIA patients were more likely to have a poorer cancer-specific survival (CSS) (hazard ratio (HR) 1.252, 95% confidence interval (CI) 1.095-1.431, P=0.001). In the subgroup of patients with LNH <12, a multivariate analysis showed that compared with stage IIA patients, stage IIIA patients were more likely to have a better CSS (HR 0.820, 95% CI 0.731-0.919, P=0.001). ConclusionsPatients with stage IIA colon cancer had a CSS comparable with that of patients with stage IIIA disease. When adequate lymph nodes were retrieved (LNH 12), stage IIA patients had a greater CSS than stage IIIA patients. On the contrary, when inadequate lymph nodes were retrieved (LNH <12), stage IIA patients had a poorer CSS than stage IIIA patients.