Radiofrequency ablation using a monopolar wet electrode for the treatment of inoperable non-small cell lung cancer: a preliminary report

Abstract

Objective: To assess the technical feasibility and complications of radiofrequency ablation (RFA) using a monopolar wet electrode for the treatment of inoperable non-small cell lung malignancies.

Materials and methods: Sixteen patients with a non-small cell lung malignancy underwent RFA under CT guidance. All the patients were non-surgical candidates, with mean maximum tumor diameters ranging from 3 to 6 cm (mean: 4.6 +/- 1.1 cm). A single 16-gauge open-perfused electrode with a 2 cm exposed tip was used for the procedure. A 0.9% NaCl saline solution was used as the perfusion liquid with the flow adjusted to 30 mL/h. The radiofrequency energy was applied for 10-40 minutes. The response to RFA was evaluated by performing contrast-enhanced CT immediately after RFA, one month after treatment and then every three months thereafter.

Results: Technical failure was observed in six (37.5%) of 16 patients: intractable pain (n = 2) and non-stop coughing (n = 4). The mean follow-up interval was 15 +/- 8 months (range: 9-31 months). The mean maximum ablated diameter in the technically successful group of patients ranged from 3.5 to 7.5 cm (mean 5.1 +/- 1.3 cm). Complete necrosis was attained for eight (80%) of 10 lesions, and partial necrosis was achieved for two lesions. There were two major complications (2/10, 20%) encountered: a hemothorax (n = 1) and a bronchopleural fistula (n = 1).

Conclusion: Although RFA using a monopolar wet electrode can create a large ablation zone, it is associated with a high rate of technical failure when used to treat inoperable non-small cell lung malignancies.

Fig. 1

73-year-old woman with lung cancer (adenocarcinoma) in the right middle lobe. A. Before radiofrequency ablation, contrast-enhanced CT scans showed 3-cm, triangular-shaped, enhanced mass in right middle lobe of lung. B. Monopolar electrode was inserted once within lung mass. C. Immediately after radiofrequency ablation, ablated zone showed almost no enhancement on contrast-enhanced CT scans and this was judged as complete ablation. D. Two years later, contrast-enhanced CT scans revealed small subpleural nodule, such as fibrotic nodule, at previous ablated zone.

Fig. 2

40-year-old man with lung cancer (adenocarcinoma) in right upper lobe. After undergoing radiofrequency ablation, patient received repeated chemotherapy and radiotherapy as treatment response was only partial ablation. A. Before radiofrequency ablation, contrast-enhanced CT scans showed 6 cm, lobulated contoured, enhanced mass in right upper lobe of lung. B. During radiofrequency ablation, monopolar electrode was inserted twice into center of mass. C. Immediately after radiofrequency ablation, contrast-enhanced CT scans showed peripheral, mildly enhanced rim outside ablated zone of lung cancer (arrow). D. Ten months later, size of ablated zone decreased in diameter (3 cm) and radiation pneumonia in right upper lobe was observed on contrast-enhanced CT. However, patient died from acute respiratory distress syndrome.