Percutaneous microwave ablation of 100 T1a renal cell carcinoma: short and intermediate term efficacy with emphasis on tumor complexity and mitigation of complications

To examine the safety and oncologic efficacy of percutaneous microwave (MW) ablation for the treatment of 100 biopsy-proven T1a renal cell carcinoma (RCC) with emphasis on tumor complexity and mitigation of complications. Retrospective single center review of 96 consecutive patients with 100 T1a N0M0 biopsy-proven RCC (68 M/28 F, mean age 66±9.4; mean tumor diameter 2.6±0.8) treated with percutaneous MW ablation between March 2011 and June 2015. Patient and procedural data were collected including BMI, comorbidities, tumor size, histology and grade, RENAL nephrometry scores, number of antennas, generator power and duration of ablation. Mean patient BMI was 32.2 (SD=8.6) and mean Charlson comorbidity index was 6 (SD=1.8). Mean RENAL nephrometry score was 6.6 (SD=1.6). Technical success, presence of local tumor progression (LTP), and complications were assessed at immediate and serial follow-up imaging. Technical success was achieved for 100 tumors (100 %) including 52 moderate to highly complex RCC. Mean clinical and imaging follow-up was 14 months (range 0-42) and 12 months (range 0-38) respectively. One treatment failure (1%) was identified at 24 months post-procedure. Local progression-free survival, cancer specific survival and overall survival were 95/96 (99%), 96/96 (100%) and 93/96 (97%), respectively. No change in eGFR was noted post-procedure (p=0.49). There were 11 (11%) early (0 – 30 days) complications with three directly related to the ablation procedure and 6 (6%) delayed complications, all urinomas. Percutaneous MW ablation is an effective treatment option for low, moderate and highly complex T1a RCC with a low rate of procedure-related complications. Long-term follow-up is needed to establish durable oncologic efficacy and survival relative to competing ablation modalities and surgery.