Objective To study the mechanism and of interventional chemotherapy through the intercostal arteries and evaluate multiple treatment plans for malignant pleural effusion with pulmonary carcinoma.Methods 20 MPE cases totally.Pleurectomy are performed on 2 cases of them with trapped lung for pathological study.The rest 18 cases were divided into three groups,6 cases in each group:carboplatin was administrated through bronchial artery in groupⅠ,through intercostal artery in groupⅡ,and through pulmonary artery in groupⅢ.All patients were treated with small-bore catheter drainage system,interventional chemotherapy and HASL.The Pt concentration in pleural effusion of three groups were compared at different time after carboplatin administration and their clinical results,side effects and life quality improvement were observed.Results Pt concentration curves of the three groups were similar to each other,rose quickly after administration of carboplatin,reached a peak 1 hour or so later,and then began to decrease slowly,but still kept certain levels after 12 hours.Pt concentration of group Ⅱwas obviously higher than that of the other two groups (P<0.05).Pt concentration of groupⅠand group Ⅲ were low,and had no difference between the two groups (P>0.05).The side effects of 18 cases were insignificant.The rates of CR+PR for pleural effusion and pulmonary carcinoma were 94.4% and 50% respectively,and life quality improved significantly after the treatment(P<0.05).Pathological study found embolus of tumor cells in lymphatic vessels of parietal pleura.Conclusion MPE with lung cancer mainly caused by parietal pleura metastasis supplied by intercostal artery,thus we may lay particular emphasis on intercostal artery intervention chemotherapy for MPE with pulmonary carcinoma.The combined therapy of small-ball catheter drainage system,local administration of HASL in pleural cavity and multi interventional therapy is safe,effective and deserving of being widely used.