Lymph node evaluation of colon cancer and its association with improved staging and survival in the Department of Defense Health Care System.

Abstract

Improved survival is associated with an increased number of lymph nodes (LNs) examined. The aim of this study was to assess whether the examination of >or=12 LNs is associated with more accurate colon cancer staging. We queried the Department of Defense Automated Central Tumor Registry database for stage I-III colon cancer patients. Logistic regression analysis was performed to determine whether the examination of >or=12 LNs is associated with increased rates of LN-positive colon cancer. Kaplan-Meier and Cox proportional hazard analysis was performed to evaluate the effect of number of LNs examined on survival. The rate of LN-positive colon cancer is significantly higher with increasing number of LNs examined (1-3 LNs examined: 31% vs. >12 LNs examined: 41%, P<.001). Logistic regression analysis adjusting for patients, tumor, and hospital characteristics showed that examination of >or=12 LNs is associated with a >30% increase in detecting a LN-positive colon cancer (odds ratio, 1.350; 95% confidence interval, 1.175-1.511). The evaluation of >or=12 LNs is associated with improved survival in LN-negative colon cancer patients (P<.001). Our study demonstrates that the proportion of LN-positive colon cancer is far higher when >or=12 LNs are examined. Examination of >or=12 LNs may improve staging accuracy and outcome with optimal use of systemic chemotherapy.