The Impact of Metastatic Lymph Node Size on Long-Term Outcomes Following Curative Colectomy for Pathological Stage III Colon Cancer

Background: In node-positive colon cancer, the impact of MLN size on prognosis is controversial. The aim of this study was to clarify the impact of metastatic lymph node (MLN) size on long-term outcomes in patients undergoing curative resection for pStage III colon cancer.Methods: This study enrolled patients who underwent curative colectomy for pStage III colon cancer between January 2013 and December 2015. All eligible patients were divided into four groups based on the short-axis diameter of the largest MLN: Group A, < 5 mm; Group B, ≥ 5 mm and < 10 mm; Group C, ≥ 10 mm and < 15 mm; and Group D, ≥ 15 mm. We performed univariate and multivariate analysis using Cox proportional hazard regression models to identify clinicopathological factors affecting recurrence-free survival (RFS).Results: A total of 209 patients were analyzed. We evaluated 7305 LNs, of which 644 were metastatic. The 5-year RFS rates of Groups A, B, C, and D were 82.3%, 74.6%, 74.5%, and 60.7%, respectively. In univariate analysis, age older than 70 years, Group D (largest MLN ≥ 15 mm), and the absence of adjuvant chemotherapy were significantly associated with RFS. In multivariate analysis, Group D (hazard ratio [HR], 3.95; 95% confidence interval [CI], 1.34–11.65; p=0.01) and the absence of adjuvant chemotherapy (HR, 2.44; 95% CI, 1.26-4.72; p<0.01) were independently associated with worse RFS.Conclusion: A maximum MLN ≥ 15 mm was significantly associated with worse RFS in stage III colon cancer. Bulky MLNs might be a poor prognostic factor in node-positive colon cancer.