摘要AIM:To investigate the changes of histology and expression of MMP-2 and nm23-H1 in primary and metastatic gastric cancer.METHODS:One hundred and seventy-seven gastric cancer patients with lymph node and/or distal metastasis between 1997 and 2001 were reviewed.Differences in histology of the primary and metastatic gastric cancer were assessed.MMP-2 and nm23-H1 immunoreactivity was compared in 44 patients with tumor infiltration to the serosa layer.RESULTS:Poorly and moderately differentiated metastatic gastric cancer was found in 88.7% (157/177)and primary gastric cancer in 75.7% (134/177) of the patients.The histological type of metastatic gastric cancer that was not completely in accordance with the preponderant histology of primary gastric cancer was observed in 25 patients (14.1%).MMP-2 immunoreactivity in metastatic gastric cancer was significantly stronger than that in primary gastric cancer,while nm23-H1 immunoreactivity showed no difference in primary and metastatic gastric cancer.CONCLUSION:Metastatic gastric cancer presents more aggressive histological morphology and higher MMP-2 immunoreactivity than primary gastric cancer.This heterogeneity may elicit a possible mechanism of gastric cancer metastasis.