Patients' survival in lung malignancies treated by microwave ablation: our experience on 56 patients

We retrospectively evaluated percutaneous CT-guided microwave (MW) ablation safety and efficacy in unresectable lung malignancies focusing on patients' survival.

All procedures were approved by the hospital ethical committee. From 2008 to 2012 we treated 69 unresectable lesions (44 lung cancer, 25 lung metastases) in 56 patients (35 men/21 women; mean age: 61.5 years). Treatment was performed under CT guidance using 14 G needles with a 3 cm active tip and a 55 W MW generator (Vivawave Microwave Coagulation System; Valley Lab). Treatment was performed at 45 W for 6-10 min. Patients were scheduled for a 3 and 6 month CT follow-up to evaluate lesion diameter and enhancement. Survival rate was evaluated by Kaplan-Meier analysis.

Ablation procedures were completed according to protocol in all patients. Pneumothorax occurred in 18 patients and 8 required chest tube. Four lesions (all >4.3 cm) were retreated 20 days after the ablation because of peripheral focal areas of residual tumor. Follow-up CT evaluation showed a decrease in maximum diameter in 44/69 lesions (64%) and in 42/59 lesions (71%) at 3 and 6 months, respectively. In all cases no pathologic enhancement was observed. Cancer-specific mortality yielded a survival rate of 69% at 12 months, 54% at 24 months and 49% at 36 months, respectively. An estimate mean for survival time was 27.8 months with a standard error of 2.8 months (95% confidence interval: 22.4-33.2 months).

Based on our experience, MW ablation seems to represent a potential safe and effective percutaneous technique in the treatment of lung malignancies. MW ablation may improve survival in patients not suitable to surgery.