Small tumors on the surface of the kidney can't escape from radio-frequency ablation treatment, according to researchers at Massachusetts General Hospital.
In the largest such study to date, researchers followed 34 patients who had been treated with RF ablation for 42 renal cell carcinoma tumors during a 3.5-year period. The team defined technical success as elimination of the entire area of tumor enhancement on imaging. They followed all patients with unenhanced and contrast-enhanced CT, excluding those patients with renal insufficiency, who were imaged with unenhanced and gadolinium-enhanced MR.
Led by Dr. Debra A. Gervais, director of abdominal intervention at Mass General, researchers were able to completely ablate all of the 29 exophytic tumors and both parenchymal tumors in one or more visits. The mean diameter of the tumors was 3.2 cm.
Tumor size and location could affect patient selection for this technique. RF ablation is most appropriate for patients with tumors 3 cm or smaller growing out of the kidney, especially tumors surrounded by fat and away from the bowel or ureter, Gervais said.
"Tumors growing out tend to be surrounded by fat that acts as an insulator, allowing higher temperatures to be reached and maintained," she said. "This helps RF ablation destroy larger tumor volumes."
The team could completely ablate only five of the 11 tumors -- all large -- that had a component in the renal sinus. Three of the six not treated completely are awaiting further ablation, and three are no longer in treatment either because of continued metastatic disease or personal preference. Central tumors are closer to large blood vessels, which act as heat sinks by continuously allowing cool blood to flow into the area.
"Patients with central tumors are more likely to experience complications," Gervais said.
Overall complication rates were low, with one minor and two major hemorrhages and one ureteral stricture among 54 ablation sessions. The study was published in the February issue of Radiology.
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