Percutaneous microwave ablation of renal masses in a UK cohort.

John, Joseph B; Anderson, Moira; Dutton, Thomas; Stott, Mark; Crundwell, Malcolm; Llewelyn, Rhys; Gemmell, Andrew; Bufacchi, Rory; Spiers, Alexander; Campain, Nicholas

OBJECTIVES To report a tertiary referral centre's experience of microwave ablation (MWA) for suspected renal cell carcinoma (RCC), describing complications and oncological outcomes. PATIENTS AND METHODS Consecutive MWA procedures (n=113) for renal masses (October 2016 to September 2019) were maintained on a prospective database. Data describing patient, disease, procedure, complications and oncological outcomes were analysed. RESULTS Median age was 68 (33-85), 73% were male, and median Charlson Comorbidity Index was 0. Median tumour diameter was 25mm (IQR 20 - 32mm). In total 95% had renal mass biopsy, with histologically proven cancer in 75%. Median R.E.N.A.L. nephrometry score was 7 (IQR 6-8). Median ablation time was 6 minutes, and length of stay was 1 day for 95%. Clavien-Dindo complication grades I, II, IIIb and IV occurred in 18%, 1.8%, 0.9% and 0.9% respectively. Median follow-up was 12 months and median renal function change was -4% (IQR -18-0%). One patient (0.9%) had local recurrence, treated with re-ablation. Two developed metastatic progression. Two (1.8%) had indeterminate findings on follow-up (one lung nodule and one possible local recurrence), managed with ongoing protocolised CT-surveillance. Post-procedure complications were associated with total ablation time (OR 1.152/min, 95% CI 1.040 - 1.277) and total ablation energy (OR 1.017/kJ, 95% CI 1.001 - 1.033). CONCLUSIONS We describe the largest UK series of MWA treatment for T1a/small T1b renal masses to date. MWA was well tolerated, with 95% discharged the following day and low complication/readmission rates. Current follow-up demonstrates favourable disease control. MWA appears to be safe and effective and should be considered in future prospective comparisons of treatments for T1a/small T1b renal masses.