Number Of Lymph Nodes Examined And Its Impact On Colorectal Cancer Staging

Objective The object of our study was to determine the number of lymph nodes that needs to be examined to accurately detect nodal metastasis and its impact on colorectal cancer staging.Methods The study included 468 patients who underwent resection in the First Affiliated Hospital of Guangxi Medical University from March 2008 to October 2010 for stageâ… â…¡â…¢colorectal cancer. The clinical and histopathologic data of patients were prospectively collected and analyzed. Statistical Package for the social sciences, version 13.0 was used for all the statistical analysis. A p value of less than 0.05 was considered to be statistically significant.Results Of 468 cases, 263 cases were lymph node-negative and 205 were lymph node-positive. Older patients (> or =71 years)were less likely to receive adequate lymph node evaluation than younger patients, and those with left-sided or rectal cancers were less likely to receive adequate lymph node evaluation than patients with right-sided cancers and transverse colon cancers. Gender and lymph nodes metastasis were no significant correlated with the number of lymph nodes after surgery. Depth of tumor invasion and lymph node positive rate was significantly correlated (P = 0.000). In the study we adopted a graph presented by Goldstein showed the relationship between the cumulative percentage of positive lymph nodes with detectable metastases and the number of lymph nodes that were recovered from those specimens. We found that 90% of node-positive cases would be detected by examination of a minimum of 27 lymph nodes in colorectal patients, and 24 lymph nodes in the left colon and rectal cancer patients. In T3 stage colorectal cancer patients, 90% of node-positive cases would be detected by examination of a minimum of 24 lymph nodes.ConclusionThe lymph-node numbers recommended by the UICC seem to be too low to declare a specimen free of metastases. The required number of lymph nodes to properly determine lymph node metastasis should be based on tumor location, T stage, patients'age ,etc.