Comparison of microwave ablation and partial nephrectomy for T1a small renal masses.

OBJECTIVE:To compare the oncological and renal function outcomes of microwave ablation (MWA) compared to partial nephrectomy (PN) in two small renal mass (SRM) tumor size cohorts, <3 cm and 3-4 cm. MATERIALS AND METHODS:This study included retrospective data from 2009 to 2015 and prospective data since 2015 from a single-institution database. Patient demographics, renal mass characteristics, and treatment outcomes were collected. Survival curves and hazard analysis were used to assess oncological outcomes. Changes in eGFR and CKD stage following surgery were used to assess renal function outcomes. RESULTS:A total of 80 PN and 126 MWA patients were analyzed. Median age and Charlson Comorbidity Index (CCI) of MWA patients were greater than PN for each tumor size cohort. Cumulative progression free survival at 36-months was 91% for MWA and 90% for PN. Preoperative renal function was significantly lower in patients undergoing MWA for both tumor sizes, however there was no significant difference in the postoperative change in renal function between MWA and PN for tumors up to 4 cm. CONCLUSIONS:Oncological outcomes and renal preservation were comparable between MWA and PN cohorts for SRMs <3cm and 3-4cm despite the MWA cohort being older and having more comorbidities. Our findings suggest that MWA can be used as a safe and effective alternative to PN for T1a renal tumors up to 4 cm.