Comparison of Safety and Efficacy of Percutaneous Microwave Ablation of Central Versus Peripheral Renal Cell Carcinoma.

PURPOSE Thermal ablation of central renal cell carcinoma has been associated with increased risk of incomplete tumor necrosis and adverse events due to the proximity of tumors to the central collecting system and hilar vessels. The purpose of this study was to compare the safety and efficacy of computed tomography-guided percutaneous microwave ablation of central versus peripheral renal cell carcinoma. MATERIALS AND METHODS An institutional database was used to retrospectively identify 114 patients with renal cell carcinoma who were treated with computed tomography-guided percutaneous microwave ablation between January 2015 and December 2019. Patients were divided into two cohorts based on tumor location: central versus peripheral. Central renal tumors were defined as being within 4 mm of renal pelvis and/or ureter and peripheral tumors were defined as tumors beyond 4 mm the renal pelvis and/or ureter. Patient demographics, tumor type, technical success, primary technique efficacy and adverse events were recorded from the medical record. Technical success, primary technique efficacy and adverse events were compared between the two cohorts. RESULTS There were 44 patients in the central group and 70 patients in the peripheral group. Technical success was 100% for both groups. There was no significant difference in primary technique efficacy rates for peripheral compared to central tumors (93% vs. 89%, p = 0.49). There was no significant difference in overall adverse event rate (17.7% vs. 11.7%, p = 0.34) or Grade II or higher adverse event rate (7.8% vs. 2.6%, p = 0.17) following microwave ablation of central versus peripheral lesions. Adjunctive maneuvers of hydrodissection and/or pyeloperfusion were performed significantly more frequently for treatment for central tumors compared to peripheral tumors (53% vs. 29%, p = 0.006). CONCLUSION When adjunctive procedures were utilized more frequently for central compared to peripheral tumors, there was no significant difference in primary technique efficacy or adverse event rate following CT-guided percutaneous microwave ablation of central compared to peripheral renal cell carcinoma. The data suggest that MWA can be successfully applied to select central renal masses and adjunctive maneuvers such as pyeloperfusion should be strongly considered for patient safety. LEVEL OF EVIDENCE III Non-randomized controlled cohort study/follow-up study.