Abstract: Objective To explore the feasibility and clinical effect of the microwave ablation technology with water circulation cooling system on treating advanced peripheral lung cancer. Methods 36 patients with inoperable advanced peripheral lung cancer were treated firstly with chemotherapy and radiotherapy. The residual tumors were then treated by microwave ablation with water circulation cooling system. Results  Operations were completed in 36 patients，the completion rate was 100%. 3 days after treatment，33 cases showed remission of cough，sputum，hemoptysis，chest pain and other symptoms，the remission rate was 91.67%3~6 months after treatment，with enhanced CT on 42 tumors，36 (85.71%) showed complete necrosis absorption，4 (9.52%) expressed as most (≥ 90%) necrotic absorption，2 showed 50% to 70% necrotic absorption. Tumor diameters were reduced 2.5 to 5cm，with the average of 4cm. 31 (86.11%) cases obtained complete remission，4 (11.11%) cases obtained partial remission and 1 (2.78%) case had no change. The total remission rate was 97.22% and clinical benefit rate was 100%，the overall survival time was 10 to 46 months，and the average survival time was 28 months.ConclusionMicrowave ablation technique with water circulation cooling system can be used as a palliative treatment for inoperable advanced peripheral lung cancer.

Key words: Microwave ablation, Lung cancer, Treatment effect