AIM: To disclose the mechanisms that accelerate or limit tumor invasion and metastasis in gastric cancer patients. METHODS: The heparanase expression,continuity of basement,degree of infiltration by dendritic cells and lymphocytes in gastric cancer tissues from 33 the early and late stage patients were examined by immunohistochemistry,in situ hybridization and transmission electron microscopy. RESULTS: Heparanase mRNA expression in the late stage patients with gastric cancer was stronger than that in the early stage gastric cancer patients. In the early stage gastric cancer tissues,basement membrane (BM) appeared intact,whereas in the late stage,discontinuous BM was often present. The density of S100 protein positive tumor infi ltrating dendritic cells (TIDC) in the early stage gastric cancer tissues was higher than that in the late stage. The infiltrating degree of tumor infi ltrating lymphocytes (TIL) in the early stage patients whose tumor tissues contained a high density of TIDC was signifi cantly higher than that in the late stage gastric cancer tissues patients with a low density of TIDC. There were few cancer cells penetrated through the continuous BM of cancer nests in the early stage gastric cancers,but many cancer cells were found outside of the defective BM of cancer nests in the late stage. CONCLUSION: Our results suggest that strongheparanase expression is related with the degradation of BM which allows or accelerates tumor invasion and metastasis. However,high density of TIDC and degree of infi ltration by TIL are associated with tumor progression in human gastric cancers. METHODS: The disclose the mechanisms that accelerate or limit tumor invasion and metastasis in gastric cancer patients. METHODS: The heparanase expression, continuity of basement, degree of infiltration by dendritic cells and lymphocytes in gastric cancer tissues from 33 the early and late stage patients were examined by immunohistochemistry, in situ hybridization and transmission electron microscopy. RESULTS: Heparanase mRNA expression in the late stage patients with gastric cancer was stronger than that in the early stage gastric cancer patients. In the early stage gastric cancer tissues, basement membrane (BM) The density of S100 protein positive tumor infi ltrating dendritic cells (TIDC) in the early stage gastric cancer tissues was higher than that in the late stage. The infiltrating degree of tumor infi ltrating lymphocytes (TIL) in the early stage patients whose tumor tissues contained a high density of TIDC wa s signifi cantly higher than that in the late stage gastric cancer tissues patients with a low density of TIDC. there are few cancer cells penetrated through the continuous BM of cancer nests in the early stage gastric cancers, but many cancer cells were found outside of the defective BM of cancer nests in the late stage. CONCLUSION: Our results suggest that strongheparanase expression is related with the degradation of BM which allows or accelerates tumor invasion and metastasis. However, high density of TIDC and degree of infi ltration by TIL are associated with tumor progression in human gastric cancers.