The Prognostic Significance of the Metastatic Lymph Node Ratio versus the Number of Affected Lymph Nodes in Patients with Colorectal Cancer Stage III Undergoing Potentially Curative Surgery

Abstract
Background: Many investigators have questioned the prognostic power of the TNM system in the prognosis of colorectal cancer because of the possibility of stage migration, and have proposed alternative prognostic methods; one of those is the lymph node ratio.
Aim of Work: The objective of this study is to compare the prognostic significance of the LNR with the absolute number of affected lymph nodes for resected colorectal ade-nocarcinoma stage III regarding overall and disease specific survival.
Patients and Methods: 55 patients with colorectal cancer stage III who underwent curative surgery were enrolled in a retrospective cohort study reviewing their medical charts from Medical Oncology Department between January 2005 and December 2006, and their five years follow-up period regarding local recurrence, metastasis and survival.
Results: The mean follow-up time was 55.1±18 months (range 6-72, median 60 months). During this time period, 12 (21.8%) patients died of disease, 20 (36.4%) patients developed local recurrence or metastasis. Overall Survival (OS) was 90.9%, 85.5%, 78.2% at 1.5, 3, 5 years respectively. Disease Specific Survival (DSS) was 90.9%, 74.5%, 63.6% at 1.5, 3, 5 years respectively.
Five year overall survival rates was significantly worse in colorectal cancers with LNR >40% (p-value <0.01, hazard ratio 0.022, 95% CI 0.003-0.17) and also worse 5 year disease specific survival (p-value <0.01, hazard ratio 0.182, 95% CI 0.075-0.44). Total LN £ 11 and positive number of LNs >4 showed significant worsening in the 5 year DSS only (p-value <0.05, hazard ratio 2.8, 95% CI 1.025-7.7) vs. (p-value <0.05, hazard ratio 0.32, 95% CI 0.13-0.8) respectively.
Conclusion: LNR was a robust prognostic indicator for node-positive colon cancers undergoing curative surgery. Because this ratio-based staging was demonstrated to reduce stage migration and to aid in identifying high-risk patients, application of the pLNR improved patient stratification in colorectal cancer and may be considered in future staging systems, it could be proposed as a standard tool for colon cancer staging.