Background: The minimum number of lymph nodes that should be evaluated in colon cancer to adequately categorize lymph node status is still controversial. The lymph node ratio (LNR) may be a better prognostic indicator. Materials & methods: We studied 1065 patients treated from 1 January 2000 to 31 August 2012. Results: Significant differences in survival were detected according to regional lymph nodes (pN) (p < 0.001) and LNR (p < 0.001). LRN and pN are independent prognostic factors. Spearman correlation analysis showed a significant correlation between the total number of dissected lymph nodes and pN (rs = 0.167; p < 0.001), but the total number of dissected lymph nodes is not significantly correlated with LNR (rs = -0.019; p = 0.550). Interpretation: In this study, LNR seems to demonstrate a superior prognostic value compared with the pN categories, in part due to its greater independence regarding the extent of lymphadenectomy.
Keywords: colorectal cancer; lymph node ratio; pN category; prognosis; treatment.
Lay abstract The prognosis of colon cancer is determined by tumor dimensions, number of metastatic lymph nodes and the presence of distant metastasis. Altogether, these criteria comprise the TNM (tumor-node-metastasis) staging system. Some societies consider a minimum of 12 lymph nodes to access the prognosis, but it is not always possible to resect this number of lymph nodes during the surgery. The lymph node ratio, calculated as the division between the number of metastatic lymph nodes and the number of resected lymph nodes, seems to demonstrate a superior prognostic value because it is independent from the extent of lymphadenectomy.