Radiofrequency Ablation Complements Radiation in Patients With Unresectable Early NSCLC

NEW YORK-Radiofrequency ablation (RFA) plus radiation is an effective and well-tolerated minimally invasive technique that warrants further investigation in early-stage non-small-cell lung cancer (NSCLC), Thomas A. Dipetrillo, MD, said at the 10th Annual International Conference on Screening for Lung Cancer. In 25 NSCLC patients with T1 and T2 disease treated with the RFA/ radiation combination, 1-year survival was 81%, reported Dr. Dipetrillo, assistant professor of radiation oncology, Brown University Medical School. "Our data suggest that these two therapies are very complementary," he said. RFA is a newer technology that researchers believe will be useful in early NSCLC cases that cannot be surgically excised because of coexisting morbidities, Dr. Dipetrillo said. The RFA technique involves insertion of a probe into the tumor. A high-frequency electrical current is generated and applied through the probe. Agitation of ions in tissue results in frictional heat, causing coagulative necrosis of tissue. "The heat can be directed at a relatively well-defined area, depending on the type of probe that is used," Dr. Dipetrillo said. "You can get to about a 3-cm spheroid type shape, and the probe can be put in through CT fluoroscopy, with excellent positioning." According to Dr. Dipetrillo, RFA is a single-day procedure that is "about as safe as biopsy itself. . . . We haven't seen any increase in toxicity above biopsy, at least for RFA alone." The procedure takes about 1 to 3 hours in the imaging room and patient recovery takes about 3 hours. In their initial experience with RFA alone, Dr. Dipetrillo and his colleagues noted that starting at about a year after the procedure, there were some increases in density along the peripheral region of the initial area of ablation. Going on the theory that not enough current was being generated to allow appropriate heating, they went on to combine RFA with radiation. Phase I Study At Rhode Island Hospital, the investigators undertook a phase I trial including 25 consecutive patients (age range, 58 to 85) with T1 or T2 NSCLC (biopsy proven and PET-confirmed node negative). All patients were medically inoperable, typically due to cardiopulmonary disease, and had received up-front cytoreduction with RFA, followed by 3D conformal radiation ± chemotherapy. Follow-up included PET (6 and 12 months) and CT (every 3 months for the first year, then every 6 months). Pulmonary function tests were given 6 months after completion of therapy. The mean lesion size treated was 3.4 cm. Immediately after the procedure, the pneumothorax rate was about 12%, consistent with what is expected from biopsy. There were no treatment-related deaths or grade 3-4 toxicities, "although these were veryhigh- risk patients," he said. Investigators noted no significant changes in pulmonary function tests. With a median follow-up of 17.2 months (range, 4 to 48 months), 1- year survival is 81% (16 of 25 patients). There have been five cancer deaths (four in T2 patients); the remaining four deaths were related to COPD or cardiovascular disease and occurred at least 6 months after RFA/ radiation treatment. Of five patients who developed metastatic disease, four were T2 patients. There was one local and one intrathoracic recurrence, both in T2 patients. Brachytherapy Studied Now, the investigators have moved from external radiation to brachytherapy. In an open protocol with an enrollment goal of 25 patients with lesions 3 cm or less in size, they are using brachytherapy immediately following RFA. "We have inserted a brachytherapy catheter to try to isolate an area of treatment and give 18 to 20 Gy to approximately 5 mm around that area," he said. To date, 12 of 14 patients have been treated successfully. "With median follow-up of 8 months, there were no local or systemic recurrences and very little toxicity, although these are very early data," Dr. Dipetrillo said.