The number of identified lymph node metastases increases continuously with increased total lymph node recovery in pT3 colon cancer

Background. The positive correlation between the number of recovered benign lymph nodes and patient prognosis is well established for stage II colon cancer patients. One theory explaining this correlation focuses on potential understaging of cancer specimen, implying that a specimen with few examined lymph nodes is likely to be assigned a lower N-stage than the correct one. Understaging may be the result of an insufficient examination of the specimen post-operatively, whereby few lymph nodes are recovered and potential lymph node metastases are overlooked. This study aims to investigate the association between the total lymph node harvest and the number of lymph node metastases in colon cancer specimen. Material and methods. We studied the original pathology reports of 649 patients diagnosed with T3 adenocarcinoma of the colon at the Department of Clinical Pathology and Genetics at Linkoping University Hospital, Linkoping, Sweden between the years 2000 and 2008. Patient demographics, specimen staging data, and lymph node recovery data were collected for each case. Results. We found a positive association between the total lymph node harvest and the number of lymph node metastases per specimen. For every additional recovered lymph node 0.17 (95% CI: 0.15-0.19) metastases were detected (p<0.001). Discussion. Our results support the conclusion that there is no minimum number of recovered lymph nodes at which an accurate determination of nodal status can be assured. Rather than focusing on a recommended minimum number of nodes, efforts should be shifted towards developing methods assuring that colon cancer specimen are dissected in a standardized way that optimizes the lymph node harvest.