The relationship of lymph node dissection and colon cancer survival in the Veterans Affairs Central Cancer Registry

Background: The extent of lymphadenectomy in colon cancer may impact potential to cure and accuracy of staging. Methods: The Veterans Affairs Central Cancer Registry database was queried for TNM stage I-III colon adenocarcinoma patients and yielded 5,823 individuals. The number of lymph nodes examined, number positive, and the positive:examined lymph node ratio were studied with respect to overall survival by using log-rank and Kaplan-Meier analysis. Results: The overall survival (OS) in stage II patients was greater with the higher number of lymph node (LN) examined. For stage II patients, the 5-year OS was 34%, 43%, 47%, and 55% for the lowest to highest quartiles (P = .007). For stage III patients, the 5-year OS was 31%, 27%, 38%, and 53% for the lowest to highest quartiles (not significant overall). OS is greater with an increased number of positive lymph nodes (P < .001). The lymph node ratio was more powerful prognostically with a 5-year OS of 27% for the highest quartile versus 44% for the lowest. Conclusions: More extensive lymphadenectomy is associated with improved OS in stage II colon cancer patients. The positive:examined LN ratio is more powerful prognostically than the number of nodes examined or LN positivity.