Using either a percutaneous, thoracoscopic, or open (thoractomy) route, an RF needle electrode is advanced into the unresectable lung tumor. Placement is guided by radiologic guidance (3D Fluoroscopy, CT , thoracoscopy, or endoscopic ultrasound. The advantage of Fluoroscopy with navigation is “real time” guidance allowing needle electrode advancement to the target tumor, thereby minimizing having to redirect the needle for optimal placement into the tumor. This would lessen complications of air leak or bleeding. The individual tines then are deployed into the tissue to surround the tumor. Following deployment, the tines are attached to an RF generator, and four dispersive electrodes (return or grounding pads) are placed on the patient, two on each thigh. An established treatment algorithm is followed to apply the RF energy (only Boston Scientific LeVeen needle electrode has an established algorhythm for RF ablation of lung tumors). The needle electrode is used to produce a thermal lesion that incorporates not only the tumor, but also nonmalignant lung parenchyma to create 1-cm-wide zone surrounding the tumor, which mimics a surgical margin. The resulting cystic-density lesion, as shown on computerized tomography (CT) scans, usually is larger than the original tumor; however, the size of this cystic area generally decreases slightly over time.

• Using high resolution Fluoroscopic, Ultrasonic or CT guidance, a radiofrequency electrode is inserted into the tumor and an umbrella-shaped array is deployed in the target tumor.
• The electrode is connected to a radiofrequency generator.

Tumor location

• Power is applied until tissue impedance (resistance to electrical current) rises
• Generator detects impedance rise and signals completion of procedure

In liver RFA, Arata found that in lesions with roll-off, the local recurrence rate at 6 months was 15%, whereas those treatments not reaching roll-off had a local recurrence rate of 43%. The recurrence rates obtained by Curley et al and Arata were lower than those reported in other studies, which suggests that monitoring tissue impedance and use of roll-off as a therapeutic endpoint may result in lower rates of recurrence.

RFA Techniques compared Boston Scientific vs Rita

1. Tissue desiccates gradually and eventually loses its ability to conduct current. 2. Target lesion becomes resistant to current flow (impedance). 3. Post RF Ablation cystic-density lesion is formed which is usually larger than the original tumor; however, the size of the cystic area decreases slightly over time.

Most patients with primary lung cancers and metastases to the lung are not candidates for surgical resection. For treatment of primary lung tumors, surgical resection remains the gold standard; however, relatively few patients are candidates for surgery. For patients with metastases to the lung and patients with lung malignancies who are not candidates for resection, RFA may provide a relatively safe, effective treatment to achieve local disease control. RFA of lung tumors can be used to debulk tumors, possibly increasing the efficacy of chemotherapy on remaining tumor cells.

Monitoring tissue impedance and use of roll-off as a therapeutic endpoint possibly could lead to lower rates of recurrence. New metastases may appear in time so continued surveillance is important. Retreatment may be beneficial in extending longevity.

• Radiofrequency ablation fills a need for addressing nonresectable lung malignancies
• While continued evaluation is necessary, clinical results to date seem favorable