AIM:To investigate the relationship between theexpression of inducible nitric oxide synthase(iNOS),vascular endothelial growth factor(VEGF),themicrovascular density(MVD)and the pathologicalfeatures and clinical staging of gastric cancer.METHODS:Immunohistochemical staining was used fordetecting the expression of iNOS and VEGF in 46resected specimens of gastric carcinoma;themonoclonal antibody against CD34 was used fordisplaying vascular endothelial cells,and MVD wasdetected by counting of CD34-positive vascularendothelial cells.RESULTS:Of 46 resected specimens of gastriccarcinoma,the rates of expressions of iNOS and VEGFwere 58.70% and 76.09%,respectively,and MVDaveraged 55.59±19.39.Judged by the standard TNMcriteria,the rate of expression of iNOS in stage Ⅳ(84.46%)was higher than those in stage Ⅰ,Ⅱ,Ⅲ(Fishexact probabilities test,P=0.019,0.023 and 0.033,respectively);the rates of expression of VEGF in stageⅢ,Ⅳ(76.0%,92.31%,respectively)were higher thanthose in stage Ⅰ,Ⅱ(Fish exact probabilities test,P=0.031,0.017,0.022 and 0.019).MVDs in stage Ⅲ,Ⅳ(64.72±14.96,67.09±18.29,respectively)werehigher than those in stage Ⅰ,Ⅱ(t=2.378,4.015,2.503and 2.450,P<0.05,P<0.001,P<0.001,P<0.05,respectively).In 37 gastric carcinoma specimens withlymph node metastasis,MVD(68.69±18.07)and therates of expression of iNOS and VEGF(70.27%,83.78%,respectively)were higher than those in the specimenswith absence of metastasis(t=2.205,x~2=6.3587,x~2=6.2584,P<0.01,P<0.05,P<0.05,respectively).MVDand the expressions of iNOS and VEGF were notcorrelated to the location,size or grade of tumor,nor withthe depth of invasion of tumor;MVDs in the positive iNOSand VEGF specimens(59.88±18.02,58.39±17.73,respectively)were higher than those in the negative iNOSand VEGF specimens(x~2=6.3587 and 6.1574,P<0.05,P<0.05,respectively);thus the expressions of iNOS andVEGF was correlated to MVD,but the expression of iNOSwas not correlated to that of VEGF.In addition,of the46 surviving patients,the 5-year survival rate ofpatients with positive iNOS or VEGF tumors wassignificantly less than that of patients with negativeINOS-or VEGF tumors(x~2=4.3842 and 5.4073,P<0.05,P<0.05,respectively). CONCLUSION:The expressions of iNOS and VEGF areclosely related to tumor angiogenesis,and are involvedin the advancement and the lymph node metastasis;thus MVD and the expressions of iNOS and VEGF mayserve indexes for evaluating staging of gastriccarcinoma and forecasting its risk of metastasis,whichwill help establish a comprehensive therapeuticalmeasure of post-operative patients and provide a newapproach to tumor therapy. AIM: To investigate the relationship between theexpression of inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF), the mycrovascular density (MVD) and the pathological features and clinical staging of gastric cancer. METHODS: Immunohistochemical staining was used for detecting the expression of iNOS and VEGF in 46rected specimens of gastric carcinoma; themonoclonal antibody against CD34 was used fordisplaying vascular endothelial cells, and MVD wasdetected by counting of CD34-positive vascularendothelial cells .RESULTS: Of 46 resected specimens of gastriccarcinoma, the rates of expressions of iNOS and VEGFwere 58.70% and 76.09% respectively, and MVDaveraged 55.59 ± 19.39.Judged by the standard TNMcriteria, the rate of expression of iNOS in stage IV (84.46%) was higher than those in stage I, II, III (Fishexact probabilities test, P = 0.019,0.023 and 0.033, respectively); the rates of expression of VEGF in stageⅢ, Ⅳ (76.0%, 92.31%, respectively) were higher thanthose in stageⅠ, (Fish exact probabilities test, P = 0.031,0.017,0.022 and 0.019) .MVDs in stageⅢ, Ⅳ (64.72 ± 14.96,67.09 ± 18.29, respectively) werehigher than those in stageⅠ, Ⅱ (t = 2.378,4.015,2.503 and 2.450, P <0.05, P <0.001, P <0.001, respectively) .In 37 gastric carcinoma specimens with lymph node metastasis, MVD (68.69 ± 18.07) and therates of expression of iNOS and VEGF (70.27%, 83.78 %, respectively) were higher than those in the specimens with absence of metastasis (t = 2.205, x ~ 2 = 6.3587, x ~ 2 = 6.2584, P <0.01, P < iNOS and VEGF were notcorrelated to the location, size or grade of tumor, nor with the depth of invasion of the tumor; MVDs in the positive iNOS and VEGF specimens (59.88 ± 18.02, 58.39 ± 17.73, respectively) were higher than those in the negative iNOSand VEGF The expressions of iNOS and VEGF were correlated to MVD, but the expression of iNOS was not correlated to that of VEGF. addition, of the 46 surviving (x 2 = 6.3587 and 6.1574, P <0.05, P <0.05, respectively) pa tients, the 5-year survival rate of patients with positive iNOS or VEGF tumors wassignificantly less than that of patients with negativeINOS-or VEGF tumors (x ~ 2 = 4.3842 and 5.4073, P <0.05, P <0.05, respectively). CONCLUSION: The expressions of iNOS and VEGF areclosely related to tumor angiogenesis, and are involved in the advancement and the lymph node metastasis; thus MVD and the expressions of iNOS and VEGF mayserve indexes for evaluating staging of gastric cancer and forecasting its risk of metastasis, whichwill help establish a comprehensive therapeuticalmeasure of post-operative patients and provide a newapproach to tumor therapy.