Impact of the number of histologically examined lymph nodes on prognosis in colon cancer: a population-based study in the Netherlands.

ABSTRACT

PURPOSE: The impact of the reported number of lymph nodes at pathologic examination of colon specimens on survival was studied. METHODS: The data of 2,281 patients with localized colon cancer were retrospectively reviewed. The effect of tumor characteristics and surgical and pathologic factors on the number of lymph nodes and examined lymph node numbers on nodal status and survival were analyzed. RESULTS: The number of examined nodes increased with T stage, left-sided tumors, and mucinous morphology, but decreased with age. The proportion of node-positive patients increased with a larger number of nodes. A high number of examined nodes and high T stage affected nodal status. The five-year overall survival was 51.3 percent for node-positive patients vs. 68.2 percent for node-negative patients. Node-negative patients had a significantly higher five-year crude and relative survival when more lymph nodes were examined. This was not found for the node-positive group and for all patients combined. CONCLUSIONS: T stage, localization, and patient age were predictive for the number of nodes examined. A higher number of examined nodes was associated with an increase in node positivity. The survival benefit can be explained by stage migration. Eventually this may lead to an overall survival benefit, as more patients are classified as node-positive, and therefore will receive adjuvant therapy.