Radiofrequency ablation for lung tumors: outcomes,effects on survival,and prognostic factors

PURPOSE

We aimed to evaluate the survival benefit achieved with radiofrequency (RF) ablation of primary and metastatic lung tumors and determine significant prognostic factors for recurrence-free survival.

METHODS

Forty-nine patients with lung cancer (10 primary and 39 metastatic) underwent computed tomography-guided percutaneous RF ablation between June 2005 and October 2013. A total of 112 tumors (101 metastatic and 11 primary non-small cell lung cancer) were treated with RF ablation. Tumor diameter ranged from 0.6 to 4 cm (median 1.5 cm). Effectiveness of treatment, complications, and survival were analyzed.

RESULTS

Primary success rate was 79.5% and local tumor progression occurred in 23 tumors. Among tumors showing progression, 10 were re-treated with RF ablation and secondary success rate was 87.5%. One-, two-, and three-year overall survival rates of 10 patients with primary lung cancer were 100%, 86%, and 43%, respectively. One-, two-, three-, four-, and five-year overall survival rates for 39 patients with metastatic lung tumors were 90%, 73%, 59%, 55%, and 38%, respectively. One-, two-, three-, and four-year overall survival rates for 16 patients with colorectal pulmonary metastases were 94%, 80%, 68%, and 23%, respectively. Complications occurred in 30 sessions (24.6%). Pneumothorax occurred in 19 sessions with seven requiring image-guided percutaneous chest tube drainage. Tumor status (solitary or multiple) and presence of extrapulmonary metastasis at initial RF ablation were significant prognostic factors in terms of recurrence-free survival.

CONCLUSION

RF ablation is a safe and effective treatment with a survival benefit for selected patients with primary and secondary lung tumors.Primary lung cancer is the leading cause of cancer-related death worldwide (1). Treatment of primary lung cancers includes surgical resection, radiation therapy, chemotherapy, and thermal ablation. Surgical resection remains the treatment of choice for patients with early stage non-small cell lung cancer (NSCLC) (2). However, primary lung cancers are generally diagnosed in advanced stages. Moreover, due to the high incidence of associated comorbidities and limited pulmonary reserve, most patients are considered ineligible for surgery (3, 4).In addition to primary cancers, lungs are the second most frequent site of metastatic disease. In selected patients with metastatic lung cancer, surgical resection is the preferred treatment. However, even patients who have undergone a complete resection have a high incidence of recurrence and may require multiple surgeries (5). Repeat thoracotomy leads to further removal of functional pulmonary tissue. Surgical resection might not be possible in patients with certain comorbidities and limited pulmonary reserve.Patients with pulmonary colorectal metastases constitute a significant portion of metastatic lung tumor group. Approximately 10% of patients with colorectal cancer develop pulmonary metastases during the course of disease (6). It has been reported that in patients with limited colorectal pulmonary metastases and no extrapulmonary disease, five-year survival following surgical resection is approximately 35%–45% (7). However, many patients are not suitable candidates for surgery.Percutaneous image-guided radiofrequency (RF) ablation is a minimally invasive technique established in the treatment of solid tumors. Since Dupuy et al. (8) reported the first clinical use of RF ablation to treat lung cancer in 2000, it has been increasingly used as a treatment option for patients with primary and secondary lung tumors, who are not surgical candidates. RF ablation offers reduced morbidity and mortality, and allows preservation of pulmonary functions because surrounding uninvolved lung parenchyma is preserved (9, 10). It is very useful for patients who have limited pulmonary reserve or with multifocal or bilateral metastatic disease. It is performed with computed tomography (CT) guidance and avoids thoracotomy in patients with significant comorbidities or in patients who refuse surgery. Repeatability of the procedure is a great advantage (11). It can be performed on an outpatient basis or with a minimum hospital stay (12).The aim of this study was to evaluate the survival benefit achieved with RF ablation for primary and secondary lung tumors and determine significant prognostic factors in terms of recurrence-free survival.