Noninvasive Ablation Relieves Chronic Chest Wall Pain

TORONTO, Ontario—Image-guided thermal ablation can provide much needed relief of chronic pain in chest wall tumor patients. According to research presented at the annual meeting of the Society of Interventional Radiology (abstract 168), thermal ablation not only relieves pain but may even contribute to longer survival. In addition, ablation may have synergistic effects with radiation therapy.

Chest wall cancer can be debilitating, and often spreads to bone, said Damian Dupuy, MD, professor of diagnostic imaging, Brown University, and Rhode Island Hospital. Indeed, skeletal metastases are present in more than 80% of advanced lung, breast, and prostate cancer patients, and of these patients, 50% to 70% have uncontrollable pain.

Dr. Dupuy pointed out that as cancer treatments are getting better at prolonging life, more people are surviving with metastatic disease—making the issue of chronic pain a growing problem.

A retrospective study was launched to evaluate the subjective benefits of palliative thermal ablation applied to tumors of the chest wall. Most patients had non-small-cell lung cancer, and the most frequent site for metastasis was the ribs. "Most of these cancers were about 2 inches in diameter when we treated them, and some were as large as 5 inches in diameter," he said.

58 Thoracic Tumors

The study included 52 adults (median age, 65 years) with 58 thoracic tumors treated with ablation—51 with radiofrequency ablation, 5 with microwave ablation, and 2 with cryoablation.

Pain was evaluated through several methods: standard pain scale measures, tracking changes in narcotic use by the patients, and reviewing individual medical records. Because of the retrospective nature of the study, evaluations were not the same for all patients. "Initially, we assessed the pain response within 2 weeks after the therapy," Dr. Dupuy said.

Follow-up data were available on 39 patients who had undergone a total of 44 ablations (median follow-up, 6 months). "More than 70% had an improved symptomatology after the treatment. In about 15% to 17%, pain was unchanged, and in about 11% it was worse," he said. Close to 67% of surviving patients reported that their pain was under control a year after ablation, showing that the treatment has durability.

Radiation/Ablation Synergy?

A correlation was seen between radiation therapy and ablation. Dr. Dupuy noted that if patients underwent radiation treatment within 90 days of their thermal ablation, "they had 100% improvement in symptoms," he said. The observation suggests a synergy between radiation and thermal ablation.

Pain relief appeared to be connected to improved survival in some patients, although this was not a study endpoint. "If they had an improvement in their pain, they had a statistically significant improvement in survival, compared with patients who did not have symptomatic relief," he said. For the 31 patients with improved pain symptoms, the 2-year survival rate was 37%, whereas all of the 8 patients with no pain relief had died by 8 months.

This raises the question of whether an improvement in survival is "related to the actual ablation or to the biology of the tumor. Obviously, if we're more effective at controlling the tumor, it can be many factors that relate to this finding. We're not sure if it's cause or effect," Dr. Dupuy said.

Pain did return in some patients: 5 (16.1%) of the 31 patients who survived to 1 year reported recurrent pain anywhere from 3 to 12 months postablation. Recurrence was unrelated to radiation treatment status. Tumor progression as seen in images did not reliably predict the level of pain symptoms. In addition, 7 patients had a postprocedural flare shortly after ablation, although 4 of these went on to achieve an overall improvement in pain. "If you can get patients over the procedural irritation from treating the tumor, they can still benefit," Dr. Dupuy said. Overall, "image-guided thermal ablation is something that should be considered for these patients," he concluded.

Another study Dr. Dupuy is involved with will address further questions about the role of palliative ablation. The ACRIN protocol 6661 trial is a multicenter prospective phase I/II study of percutaneous radiofrequency ablation of bone metastases using CT guidance. Results are expected in the fall of 2006.