Objective To investigate the clinical efficacy and safety of CT-guided percutaneous microwave ablation (MWA)in elderly patients with early-stage lung cancer who were unable to underwent surgery,and to evaluate the risk factors for prognosis.Methods A total of 51 patients with early stage(stages Ⅰ and ⅡA)non-small cell lung cancer (NSCLC)who underwent MWA in Beijing hospital from January 2016 to December 2018 were collected as the MWA group.And 50 patients with similar age and gender receiving lobectomy surgery were collected as the control group.In a retrospective follow-up study,the clinical efficacy and safety of treatment were compared between the study(n=51)and control(n=50)groups.Kaplan-Meier survival analysis was used to assess the overall survival and local recurrence-free survival.COX analysis was used to evaluate the risk factors.Results Of the 101 patients,62 were male(61.4％),aged 60-85 years(average,72.3± 11.6 years).There was no significant difference in baseline characteristics,including age,gender,smoking,medical history,lung function,tumor size,pathological type and histological grading,tumor position and clinical stage between the two groups(P＞0.05).There were no serious complications in the MWA group during perioperative period,and 14 cases (27.5％)had a small amount of pneumothorax after operation,which were absorbed after special treatment.Five cases (9.8％)had a small amount of hemoptysis,7 cases(13.7％)had a small amount of pleural effusion,9 cases(17.6％)had low fever (＜ 38.5 ℃),and 9 cases (17.6 ％) had postoperative mild pain.There were no serious complications in the control group.The follow-up period was up to December 31,2018,and the median follow-up time was 11.7 months(4.5 20.3 months).During the follow-up,local recurrence occurred in 10 patients(9.9％),including 7 patients(13.7％)in the MWA group and 3 patients(6.0％)in the control group.There was no significant difference between the MWA group and the control group in the 1-year overall survival rate(92.2％ or 47 cases vs.96.0％ or 48 cases,P =0.313),tumor-specific survivalrate(100.0％ vs.100.0％,P=1.00),local recurrence free survival rate(86.3％ or 44 cases vs.94.0％ or 47 cases,P =0.156).Multivariate COX regression analysis showed age (HR =1.22,95 ％CI:1.06-1.38,P =0.004),tumor size (HR =1.75,95 ％ CI:1.14-2.36,P =0.005) and clinical stage of tumor(HR =1.53,95 ％ CI:1.17-1.89,P =0.001) were risk factors for the local recurrencefree survival.Conclusions MWA is an effective and safe treatment for elderly patients with early-stage lung cancer who are not suitable for surgery.Age,tumor diameter and clinical stage are risk factors for local recurrence-free survival.