Malignant tumor and eosinophils. I. Prognostic significance in gastric cancer.

A prospective study with 647 gastric cancer was performed. Resected tumor specimens from 647 patients were examined with respect to eosinophil infiltration. Infiltration of the primary tumor by eosinophils was found to have a marked prognostic significance. Five years after the resection of tumor in the patients with gastric cancer, 29 of 51 patients (56.0%) who showed previously the infiltration of more than 100 eosinophils in tumor tissue were alive, while only 38.6% (61/158) of the patients with the infiltration of less than 100 eosinophils survived (P less than 0.05). Eosinophil infiltration in the resected tumor was detected in 157 patients (24%). The intensive degree of infiltration correlates well with a special pathologic type of cancer, poorly differentiated adenocarcinoma, the size of tumor mass and preoperative blood eosinophilia. The extract from tumors with the marked eosinophilic infiltration was highly chemotactic for eosinophils in vitro. The eosinophil chemotactic activity was found to be heat-labile and nondialyzable. It was therefore considered most likely that eosinophil infiltration in the tumor and blood eosinophilia observed in some patients with gastric cancer were caused by an eosinophil chemotactic factor of gastric cancer and the good indication of the prolonged survival of the patients.