Perinodal involvement of cancer cells in gastric cancer patients

Background. En-bloc resection for cancer has been a standard procedure based on the concept that there may be a small number of "invisible" cancer cells around the Primary tumor and metastatic lymph nodes. However, there are few histopathologic studies of this issue. Methods. Perinodal involvement of cancer cells, defined as existence of cancer cells in the attached fatty tissue around the dissected lymph nodes, was assessed in 123 node-positive and 15 node-negative gastric cancers by both hematoxylin-eosin staining and immunohistochemistry. Results. Perinodal involvement was found in 79 (5 7%) of the 138 patients. The incidence was higher in patients with tumors invading the deeper layer, the macroscopic diffuse type, the presence of lymphatic or vascular invasion (P < .05), and advanced disease (stage I, 17%; 11, 62%; III, 67%; IV, 80%). Survival of patients with perinodal involvement was less than that of Patients without perinodal involvement (46% vs 87%; P < .005). Perinodal involvement was found, by multivariate analyses, to be a significant prognostic factor. Conclusions. Perinodal cancer cells are observed frequently in gastric cancers with lymph node metastases, and the involvement appears to be a reliable prognostic factor for gastric cancers.