Abstract No. 507 Microwave ablation of T1a renal cell carcinoma: immediate short-term outcomes

Abstract

Studies demonstrating the technical efficacy and short-term outcomes in patients with cT1a small renal masses treated with microwave ablation are lacking. As such the American Urological Association has no current recommendations regarding microwave ablation (MWA) in clinically localized T1a renal cell carcinoma. We aim to describe our initial experience with microwave ablation in these patients to demonstrate technical efficacy and clinical outcomes. We performed an IRB-approved single-center retrospective analysis of percutaneous microwave ablations at our institution. Seventy-nine small renal masses in 72 consecutive patients were identified between October 2016 and June 2018. Patients with an embolization, biopsy alone, or non-neoplastic pathology were excluded from evaluation leaving 53 renal masses in 50 patients. Patient, tumor, ablation, admission, and follow-up characteristics were documented. Successful ablation of the renal cell carcinomas was evaluated using technical success and technique efficacy as defined by the International Working Group on Image Guided Tumor Ablation in October 2014. A single Clavien Dindo I complication (nausea with vomiting) and no grade II-V complications occurred in this patient population. A renal mass biopsy was performed prior and during ablation in 10 (18.9%) and 43 (81.1%) of 53 renal tumors, respectively. The renal biopsy was diagnostic in 100% of the patients. Immediate follow up 4.4 (0.4- 16.8) months showed technical success and technique efficacy in 53 (100%) and 52 (98%) of 53 ablated tumors respectively. Specifically, primary technique efficacy was achieved in 98% of patients with 1 of 53 tumors showing residual unablated tumor on follow up imaging. Secondary efficacy was achieved after re-treatment of this tumor. In this initial evaluation of 53 T1a renal cell carcinomas in 50 patients at our institution between October 2016 and June 2018 microwave ablation has excellent immediate technical success and technique efficacy with low morbidity at a mean follow up of 4.4 (0.4-16.8) months.Table 1Patient, Tumor, Ablation, Admission, and Follow-up CharacteristicsPatient Characteristics (n=50)Male82%Charlson Index*3.81 (2.8)Age* (yr)68 (10.84)BMI*27.7 (3.5)Tumor Characteristics (n=53)Size*2.11 (0.73)Pathology GroupClear Cell 25 (47.2%), Papillary 11 (20.8%), Oncocytic 8 (15.1%), Other 6 (11.3%), Chromophobe 2 (3.7%)R.E.N.A.L. score*4.65 (1.40)Procedure Characteristics (n=53)Simultaneous Biopsy81.1%Power* (Watts)65.10 (9.00)Duration* (min)8.74 (3.56)Post-operative Characteristics (n=50)Admission length (hr)†3.140.7-8.57Length of Follow Up (mo)†4.40.4-16.8Complication12%Retreatment12%* Mean (standard deviation).†Mean (range). Open table in a new tab