The effect of tumor size and location on efficacy and safety of US- and CT- guided percutaneous microwave ablation in renal cell carcinomas.

Purpose: To evaluate the effect of size and central location of the tumor on safety and efficacy of percutaneous CEUS- and CT-guided MWA in biopsy-proven renal cell carcinomas (RCCs).
Materials and Methods: In this IRB-approved retrospective study, 69 biopsy-proven renal tumors in 56 patients, who underwent MWA in our institution from January 2013 to March 2017, were evaluated. Data collection included demographics, tumor characteristics, procedural protocols, and follow-up visits within 6 months post procedure. Primary outcomes were assessed by technical success (TS), local tumor progression (LTP), and complications. The Kaplan-Meier analysis was used for survival rate.
Results: Overall technical success was achieved for all 69 lesions (92.8% primary TS, 100% overall). Median nephrometry score was 8 (4-11) and median tumor size was 2.5 cm (0.8-7). Five lesions which required second ablation had significantly higher median tumor size 4 cm (P = 0.039) with the same nephrometry score. Renal function remained stable with no significant change in eGFR before or after ablation. The LTP rate was 5.8%. The most recurrent tumors were clear cell (50%) followed by papillary tumors (25%). The complication rate was 5.8% with minor complications (hematoma and pain) and no major issues. There was no significant association between nephrometry score and technical success, recurrence, or complication rates. Overall and tumor-specific survival rates were 96.7% and 100% at 11.9 months.
Conclusions: Image-guided MWA appears to be a safe and effective treatment regardless of nephrometry score and tumor location with high technical success, low recurrence, and complication rates.