Doubts linger over next stage of lung RF ablation

Researchers need more data to better define technique's value in various tumors and patients

Radio-frequency ablation of lung malignancies has been proven technically feasible and safe. More studies are needed, however, to understand exactly where the technique fits in with various patient populations, stages of disease, and tumor types.

"You can't compare survival and local control between metastases and primary lung cancer because the patient and tumor biology are so different. Also, many patients are treated in combination with both external radiation and brachytherapy, and this should give us better results compared with ablation alone," said Dr. Damian Dupuy, a professor of diagnostic imaging at Brown Medical School in Providence, RI.

Currently available data provide clues as to which patients can benefit most from RFA. Although surgery should be the first line of treatment for those with very early stage primary lung tumors, patients deemed inoperable because of severely impaired pulmonary function or substantial comorbidity could do well with RFA, said Dr. Riccardo Lencioni, an interventional radiologist at the University of Pisa in Italy.

"In more advanced tumors, RFA has been used for debulking purposes, for pain palliation, or in a combined strategy with conventional treatments such as chemotherapy or radiation therapy," Lencioni said.

A formal trial including a standardized patient population and clearly defined evaluation parameters could provide definitive answers about RFA's role in the clinical management of patients with lung cancer. Such a trial is under way, said Dr. Robert Suh, director of thoracic interventional services at the David Geffen School of Medicine at the University of California, Los Angeles. The RF Treatment of Stage I Lung Cancer in a High-Risk Population multicenter study will be conducted under the auspices of the American College of Radiology Imaging Network and the American College of Surgeons Oncology Group. The pilot study, already approved by the National Cancer Institute's Cancer Therapy Evaluation Program, may enroll about 50 patients and should begin sometime this year.

Several studies reported at the last RSNA meeting indicate the current status of RFA. Dupuy and colleagues found that 60% of 126 inoperable patients who underwent RFA for tumor control are still alive, while 28% have died from causes unrelated to RFA. They also observed that, among complications, the pneumothorax rate was higher in cases in which expandable needles with multiple hooks had been deployed.

Lencioni reported on 14 patients with stage IA non-small cell lung cancer who were unfit for surgery or radical radiotherapy. After one-year follow-up, his group recorded an overall survival rate of 81% and a cause-specific survival rate of 100%.

Boston researchers led by Dr. Eric vanSonnenberg, formerly an interventional radiologist at Brigham and Women's Hospital, found a one-year survival rate of 86% in 30 patients. His group used several procedures to assist RFA, including saline solution instillation, intercostal and paravertebral nerve blocks, and intraprocedural pneumothorax drainages.

At UCLA, Dr. Amanda Wallace, a resident at the David Geffen School of Medicine, and colleagues found that long-term disease continued in half of 16 patients, at the RFA site in two cases and within the same lobe in one. Another Italian team, led by Dr. Giuseppe Belfiore from San Sebastiano Hospital in Caserta, reported similar results. Of 40 patients with primary lung cancer, 25 showed clinical improvement at six months, and 11 at one year.

Researchers agree that RFA cannot go head-to-head with surgery for early-stage, primary malignancy at this time. Most of them frequently treat patients considered nonoperable because of high comorbidities, which often kill them before their tumors do. Either for disease control or palliation, physicians may resort to RFA with discretion until more definitive data become available.

"The big picture is, choose your patients wisely and work with a team of cancer specialists," Dupuy said.