Impact of difference in the definition of extranodal spread on the outcome of node-positive patients with gastric cancer

Previous studies have reported that extranodal spread is a prognostic factor in patients with several solid cancers. However, the definition of extranodal spread varies with the reporting investigator and has not been standardized yet. Therefore, we selected several widely used definitions from previous reports and comparatively assessed the clinicopathologic significance of these definitions. Extranodal spread in the 103 node-positive patients who had received curative resections for gastric cancer was classified into two groups, viz., (a) capsule rupture, where cancer cells infiltrated into the perinodal fatty tissue beyond the capsule of the involved lymph node, and (b) no capsule rupture, where nests of cancer cells were detected demonstrable in adjacent tissues around the metastatic lymph node without rupture of the capsule. Sixty-five (63.1%) of the 103 patients showed extranodal spread. Of the 65 patients, 50 patients showed the capsule rupture type and 15 showed the no capsule rupture type of extranodal spread. The 5-year survival rate was significantly poorer in the capsule rupture group as compared with that in the no capsule rupture group and extranodal spread-negative group (P < 0.05 and P < 0.01, respectively). In regard to the mode of recurrence, the rate of peritoneal recurrence was significantly higher in the capsule rupture group (P < 0.01). In the assessment of patients with extranodal spread, it is considered important to classify the patients based on the status of extranodal spread into the capsule rupture group and no capsule rupture group.