Clinicopathologic factors associated with lymph node retrieval in resectable colon cancer: A veterans' affairs central cancer registry (VACCR) database analysis

Background: A long-term determinant of survival in resectable colon cancer is the involvement of regional lymph nodes. We evaluated the clinicopathologic factors associated with lymph node retrieval. Methods: We conducted a retrospective analysis of patients with resected stage I-III colon cancer in the Veteran's Affairs Central Cancer Registry between 1995 and 2008. One-way ANOVA compared the differences between various groups. Multivariate logistic regression analysis was performed to determine the factors associated with the harvest of 12 or more lymph nodes for pathologic examination. Results: There were 19,240 patients with resectable colon cancer included in our analysis. Mean number of lymph nodes retrieved increased with later year of diagnosis, higher overall stage, higher T descriptor, age <65 years, poorer differentiation and right-sided tumors (P<0.01 for all covariates). These aforementioned factors are also associated with an increased probability of retrieving 12 or more lymph nodes after surgical resection (P<0.01 for all covariates). Conclusions: Later year of diagnosis, younger patients, right-sided tumors, poorer differentiation, higher T descriptor and overall stage are associated with increased number of lymph nodes retrieved. These may indicate the presence of an immunological response of tumor versus host affecting lymph node retrieval.