Introduction of Microwave Ablation Into a Renal Ablation Practice: Valuable Lessons Learned

The purpose of this study was to evaluate the early outcomes of percutaneous microwave ablation (MWA) for clinical stage T1 (cT1) renal masses when performed within a high-volume ablation practice with critical emphasis on procedural safety.

A retrospective review of a percutaneous renal ablation registry identified 26 patients with a total of 27 cT1 renal masses treated with MWA between 2011 and 2017. Mean patient age was 63.8 years and 16 (61.5%) patients were male. Mean renal mass size ± SD was 2.3 ± 0.8 cm (range, 1.1-4.7 cm). The main outcome parameters investigated were technical success, local tumor progression, survival rates, and complications. Complications were categorized using the Clavien-Dindo classification system. Rates of local progression-free and cancer-specific survival (PFS and CSS, respectively) were estimated using the Kaplan-Meier method.

Technical success was 100% on contrast-enhanced CT or MRI performed immediately after renal MWA. Twenty-four patients (92%) with 25 tumors had follow-up imaging for 3 months or longer (mean, 20.6 ± 11.6 months), with no local tumor recurrences identified. Estimated 3-year local PFS and CSS were 96% and 94%, respectively. The overall complication rate was 19.2%; two patients (7.7%) experienced minor complications (grade I or II) and three patients (11.5%) experienced major bleeding or urinary-related complications (grade III or higher), including one death.

This study suggests that percutaneous MWA is a promising minimally invasive treatment option for cT1 renal masses. Nonetheless, major bleeding and urinary-related complications can occur, and further studies are needed to determine optimal patient and tumor selection for renal MWA.

AJR. American journal of roentgenology. 2018 Sep 24 [Epub ahead of print]

Scott M Thompson, John J Schmitz, R Houston Thompson, Adam J Weisbrod, Brian T Welch, Boyd R Viers, James D Hannon, Grant D Schmit, Thomas D Atwell, A Nick Kurup

1 Department of Radiology, Mayo Clinic School of Medicine, 200 1st St SW, Rochester, MN 55905., 2 Department of Urology, Mayo Clinic School of Medicine, Rochester, MN., 3 Department of Anesthesiology, Mayo Clinic School of Medicine, Rochester, MN.