Objective    To investigate the relationship of matrix metalloproteinase-9 (MMP-9) expression and angiogenesis in lung carcinoma tissue and its significance.     Methods    Totally 84 patients were subjected

including 40 cases of  lung squamous cell carcinoma

34 of  lung adenocarcinoma    and 10 of  small cell lung cancer. Twenty samples of normal adjacent tissues served as control. The expression of MMP-9 and CD34 was detected in these 104 lung tissue samples by immunohistochemical method. The expression of MMP-9 was analyzed with clinical pathological data and microvascular density (MVD).     Results    The expression of MMP-9 in lung carcinoma tissues was significantly higher than that in para-cancerous normal lung tissues (P0.01). Small cell lung cancer and adenocarcinoma had higher MMP-9 expression than squamous cell carcinoma (P0.01). The expression of MMP-9 was significantly higher in lung carcinomas with lymph node metastasis than in lung carcinomas without lymph node metastasis (P0.01)

higher in stage-Ⅲ and -Ⅳ tumors than in stage-Ⅰ and -Ⅱ (P0.05). MVD was significantly higher in lung carcinomas with MMP-9 positive than in those negative (P0.01).     Conclusion    MMP-9 can improve the neovascularization of lung carcinoma

and is closely correlated with invasion and metastasis of lung carcinoma.