Low-energy Intermittent Percutaneous Microwave Ablation For The Treatment Of Pulmonary Tumors At Special Anatomy Site

ObjectiveIn recent years,great progress had been made in the clinical research of microwave ablation for lung cancers.However,the current researches were mainly about the ablation of tumors at low dangerous anatomy sites,and the ablation powers were usually high-energy(60W-80W).For some tumors of high dangerous anatomy sites such as near the pleura or invading the pleura or near the heart or near diaphragm or near the thoracic aorta,the effectiveness and safety of microwave ablation were reported rarely.For these tumors of high dangerous anatomy sites,we choose the low-energy ablation power 50 W and intermittent ablation(keep ablating for 3-5 minutes and rest 2 minutes).The temperature in the ablation area is relatively low,and the ablation range is relatively small in the same time.Theoretically,the safety is relatively high.The purpose of this study is to study the effectiveness and safety of low-power intermittent microwave ablation at 50 W for the treatment of lung cancer(primary and metastasis)at special anatomy sites such as near the pleura or invading the pleura or near the heart or near the diaphragm or near the thoracic aorta.Materials and MethodsA retrospective review was undertaken of 42 patients(34 men,8 women;median age,63y;range,29-81y)who were hospitalized at Affiliated Hospital of Taishan Medical University between June 2014 and December 2017,and 44 pulmonary tumors were underwent low-energy intermittent MWA.Primary tumor origin was lung(n=29),colorectal(n=1),esophageal(n=8),kidney(n=4),and bile duct(n=1).Median tumor size was 28 mm(range,7-50 mm).There were 44 cases near the pleura or invading the pleura,4 cases near the thoracic aorta,5 cases near the heart,6 cases near the diaphragm.We chose the low-energy ablation power 50 W and intermittent ablation(keep ablating for 3-5 minutes and rest 2 minutes).If the diameter of tumors were ≤3 cm,we use single needle ablation.However the diameter of tumors were > 3 cm and ≤5 cm,we chose double needle.And we chose intermi-ttent ablation based on response during patient ablation.The rates of local control of ablation were recorded.And pneumothorax,pleural effusion,pain,infection,cardiac events,pleural bronchial fistula,diaphragmatic injury,pseudoaneurysm,hemoptysis and other adverse reactions were recorded respectively.Technique effectiveness was assessed by longitudinal follow-up CT scan.ResultsComplete ablation was performed in 37 tumors undergoing 50 W low-power intermittent microwave ablation with a complete ablation rate of 84.09%(37/44).A complete ablation rate of 96.15%(25/26)was achieved in tumors whose diameters were ≤3cm,and complete ablation rate of tumors whose diameters > 3 cm were 66.67%(12/18).P value was < 0.05,and the two groups had statistical significance.The overall incidence rate of pneumothorax was 29.55%(13/44).The incidence rate of pneumothorax for the tumor invading the pleura was 10.53%(2/19),and the incidence rate of pneumothorax for the tumor near the pleura(0 <distance from the pleura ≤10mm)was 44%(11/25).P value was < 0.05,and the two groups had statistical significance.The overall incidence of pleural effusion was 27.27%(12/44).The incidence rate of pleural effusion for the tumor invading the pleura was 47.37%(9/19),the incidence rate of pleural effusion for the tumor near the pleura(0 < distance fro-m the pleura ≤ 10mm)was 12%(3/25).P value was < 0.05,and the two groups have statis-tical significance.35 cases were recorded in pain and they were given intraoperative analg-esic drugs during the operation,and they were not recorded in pain after surgery.There are 4 persons who have pulmonary infection.After been given hormone and antibiotics,the in-fection was controlled.In the group of 5 cases near the heart,only one case has postoperat-ive atrial fibrillation and cardiac insufficiency.Symptoms disapeared after they were given amiodarone,cardiac diuretic and other drugs.For the 6 cases near diaphragm,2 cases suff-ered diaphragmatic injury after ablation.The pleura bronchial fistula was not recorded.Th-ere were no hemoptysis and deaths.Conclusions50w low-power intermittent microwave ablation was safe and effective for tumors which were near or invading the pleura,near the heart,near the diaphragm,near the thoracic aortic.Complete ablation rates were higher in tumors whose diameters were ≤3 cm.The risk of pneumothorax was greater in the tumors near pleural lesion than tumors invading the pleural.Tumors invading the pleural were associated with a greater risk of pleural effusion than the tumors near the pleural.Low-power intermittent microwave ablation could cause pain but the pain could be tolerated.The probability of infection was low and was within controllable range.Diaphragm injury and myocardial damage could happen,and it could be cured.Bronchial pleural fistulas had a lower probability.