Reviewer: James M. Metz, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: June 3, 2007
Presenter: M. O. Meyers
Presenter's Affiliation: Duke University Medical Center
Type of Session: Scientific
It is well known that lymph node metastasis is associated with a worse outcome in rectal cancer. It has generally been accepted that 12 lymph nodes are needed for proper nodal staging. However, only 37% of patients in the SEER database with colon cancer had 12 lymph nodes evaluated. The Intergroup 0114 trial for rectal cancer had 52% with less then 10 lymph nodes evaluated. Because many patients are not having the recommended number of lymph nodes evaluated, this study was designed to determine if the ratio of positive lymph nodes to total examined lymph nodes is of prognostic significance.
Materials and Methods
This study quantitates what most physicians already do when evaluating a pathology report for rectal cancer in the postoperative setting. It is consistent with what is expected that the overall tumor burden predicts outcome in this disease. Because many patients do not have adequate lymph nodes examined, this study helps to better define the risk of nodal disease based on the number of lymph nodes removed. However, most patients with locally advanced rectal cancer are now treated with neoadjuvant chemotherapy and radiation therapy and this model is not predictive of that group of patients. It is also unclear what is an adequate number of lymph nodes evaluated after neoadjuvant treatment because it is much harder to locate the nodes in the specimen after these therapies.