Reviewers: Kenneth Blank, M.D. and Leonard Farber, M.D.
Source: New England Journal of Medicine examines new technology which may help pathologists better determine if cancer has invaded a lymph node. A total of 68 patients with esophageal cancer who underwent excision of the entire esophagus and surrounding lymph nodes were enrolled in this study. In total 1308 lymph nodes were examined and 399 of these were determined to be tumor-free by routine pathology studies. These 399 lymph nodes were examined further by immunohistochemical studies (IHC) to determine if cancer not detected by routine pathological evaluation could be detected by IHC. IHC utilizes monoclonal antibodies which bind to cancer cells but not normal cells. These antibodies are tagged with a fluorescent marker which makes it easy to see under the microscope.
Seventeen percent of the 399 lymph nodes which were 'tumor-free' on routine analysis stained positive with the antibody. 15 of the 30 patients who were staged N0 by the usual pathologic methods had positive nodes (N1). The presence of cancer in the lymph nodes found by IHC was predictive of significantly reduced overall survival. Importantly, all patients whose lymph nodes were negative by routine and IHC study were living at last follow-up without evidence of recurrence. The authors conclude that IHC examination of lymph nodes may improve the pathologic staging of esophageal cancer.