Background: The objective of this study was to assess the value of metastatic lymph node ratio in predicting prognosis of patients with stage III colorectal cancer.
Methods: From 2000 to 2005 inclusively, a total of 626 patients featuring stage III colorectal cancer underwent curative resection. These patients were stratified into LNR groups: 1 (0 < LNR ≤ 0.1); 2 (0.1 < LNR ≤ 0.25); 3 (0.25 < LNR ≤ 0.5); and 4 (LNR > 0.5). The follow-up was closed in April 2010. Kaplan-Meier survival curve and log-rank test were used to evaluate the prognostic value of LNR. A Cox regression model was used for multivariate analyses.
Results: With a median follow-up period of 42.2 months, 5-year overall survival for groups LNR1, LNR2, LNR3, and LNR4 was 73%, 64%, 44%, and 22%, respectively. In the multivariate analysis, the LNR was an independent prognostic factor for survival (P < 0.001). LNR remained statistically significant (P < 0.001), both in patients with colon and rectum cancer regardless of the number of lymph nodes retrieved (≥12 or < 12). The survival rate of ratio group LNR1 was better than ratio group LNR4 (P < 0.001) for patients with the same IIIB or IIIC staging.
Conclusions: LNR is an accurate prognostic method for patients with stage III colorectal cancer. We proposed an algorithm to incorporate LNR into current AJCC staging system to form new staging.