Lymph node yield and tumour subsite are associated with survival in stage I–III colon cancer: results from a national cohort study

BACKGROUND: It has been suggested that apart from tumour and nodal status, a range of patient-related and histopathological factors including lymph node yield and tumour location seems to have prognostic implications in stage I–III colon cancer. We analysed the prognostic implication of lymph node yield and tumour subsite in stage I–III colon cancer. METHODS: Data on patients with stage I to III adenocarcinoma of the colon and treated by curative resection in the period from 2003 to 2011 were extracted from the Danish Colorectal Cancer Group database, merged with information from the Danish National Patient Register and analysed. RESULTS: A total of 13,766 patients were included in the analysis. The 5-year overall survival ranged from 59.3% (95% CI 55.7–62.9%) (lymph node yield 0–5) to 74.0% (95% CI 71.8–76.2%) (lymph node yield ≥ 18) for patients with stage I–II disease (p < 0.0001) and from 36.4% (95% CI 29.8–43.0%) (lymph node yield 0–5) to 59.4% (95% CI 56.6–62.2%) (lymph node yield ≥ 18) for patients with stage III disease (p < 0.0001). The 5-year overall survival for tumour side left/right was 59.3% (95% CI 57.9–60.7%)/64.8% (CI 63.4–66.2%) (p < 0.0001). In the seven colonic tumour subsites, the 5-year overall survival ranged from 56.6% (95% CI 51.8–61.4%) at splenic flexure to 65.8% (95% CI 64.5–67.2%) in the sigmoid colon (p < 0.0001). In a cox regression analysis, lymph node yield and tumour side right/left were found to be prognostic factors. Tumours at the hepatic and splenic flexures had an adverse prognostic outcome. CONCLUSION: For stage I–III colon cancer, a lymph node yield beyond the recommended 12 lymph nodes was associated with improved survival. Both subsite in the right colon, as well as subsite in the left colon, turned out with adverse prognostic outcome questioning a simple classification into right-sided and left-sided colon cancer.