“At UW, we have treated approximately 200 early-stage (T1a RCC) with 0 episodes of major bleeding and only 6 urinomas,” Dr Wells told Cancer Therapy Advisor. “Similar rates are seen in the other large studies around the world.”

Because kidney and renal tumor tissues are very vascular, ablation must overcome local heat-sink effects, and MWA is particularly well-suited for that task, Dr Wells said. That appears to explain some early signs of improved treatment outcomes, compared with other ablation modalities, he said.4,6

But effective ablations can be achieved using radiofrequency and cryoablation, as well, Dr Wells emphasized. 

“Outcomes depend largely on the expertise of the physician performing the procedure,” he commented. “That said, reportable durable oncologic outcomes are better for MWA compared [with] radiofrequency for localized RCC larger than 3 cm. Oncologic control for T1a (4 cm or smaller) and T1b (4.1 cm to 7 cm) are similar for microwave and cryo, when looking at [outcomes at] the best centers in the US and around the world.”

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The cautery effect of heat-based ablation yields lower bleeding rates than cryoablation. While small (T1a) tumors treated with cryoablation have a low risk for significant bleeding, larger (T1b) renal tumors can be embolized before cryoablation to reduce the risk for postprocedure bleeding, Dr Wells noted.

Nevertheless, despite taking the appropriate precautions, bleeding does sometimes occur, the authors of the Mayo study and other studies have shown.