A Distribution Weighted Prognostic Scoring Model for Node Status in Advanced Rectal Cancer

PURPOSE: There are various lymph node-based staging systems. Nevertheless, there is debate over the use of parameters such as the number of involved lymph nodes and the lymph node ratio. As a possible option, the distribution of metastatic lymph nodes may have a prognostic significance in rectal cancer. This study is designed to evaluate the impact of distribution-weighted nodal staging on oncologic outcome in rectal cancer. MATERIALS AND METHODS: From a prospectively maintained colorectal cancer database of our institution, a total of 435 patients who underwent a curative low anterior resection for mid and upper rectal cancer between 1995 and 2004 were enrolled. Patients were divided into 3 groups according to the location of apical metastatic nodes. A location-weighted prognostic score was calculated by a scoring model using a logistic regression test for location based-statistical weight to number of lymph nodes. All cases were categorized in quartiles from lymph node I to lymph node IV using this protocol. RESULTS: The location of lymph node metastasis was an independent factor that was associated with a poor prognostic outcome (p<0.001). Based on this result, the location-weighted-nodal prognostic scoring model did not show lesser significant results (p<0.0001) in both overall survival and cancer-free survival analyses. CONCLUSION: The location of apical nodes among the metastatic nodes does not have a lesser significant impact on oncologic result in patients with advanced rectal cancer. A location-weighted prognostic scoring model, which considered the numbers of involved lymph nodes as the rate of significance according to the location, may more precisely predict the survival outcome in patients with lymph node metastasis.