Percutaneous microwave ablation of T1a and T1b renal cell carcinoma: short-term efficacy and complications with emphasis on tumor complexity and single session treatment

Purpose To update the oncologic outcomes and safety for microwave (MW) ablation of T1a (≤4.0 cm) and T1b (4.1–7.0 cm) renal cell carcinoma (RCC) with emphasis on tumor complexity and single session treatment. Materials and Methods Retrospective review of 29 consecutive patients (30 tumors) with localized (NOMO) RCC (23 T1a; 7 T1b) treated with percutaneous MW ablation between 3/2013 and 6/2014. Primary outcomes investigated were technical success, local tumor progression (LTP), and complications. Technical success was assessed with contrast-enhanced computed tomography (CECT) immediately after MW ablation. Presence of LTP was assessed with CECT or contrast-enhanced magnetic resonance at 6-month target intervals for the first two years and annually thereafter. Complications were categorized using the Clavien-Dindo classification system. Results Median tumor diameter was 2.8 cm [IQR 2.1–3.3] for T1a and 4.7 cm [IQR 4.1–5.7] for T1b tumors. Median RENAL nephrometry score was 7 [IQR 4–8] for T1a tumors and 9 [IQR 6.25–9.75] for T1b tumors. Technical success was achieved for 22 T1a (96%) and 7 T1b (100%) tumors. There were no LTP during a median imaging follow-up of 12.0 months [IQR 6–18] for the 23 patients (24 tumors) with greater than 6 months of follow-up. There were three Clavien-Dindo grade I–II complication (10%) and no Clavien-Dindo grade III–V complications (0%). All but two patients (93%) are alive without metastatic disease; two patients died after 12-month follow-up of causes unrelated to the MW ablation. Conclusion Percutaneous MW ablation appears to be a safe and effective treatment option for low, moderate, and highly complex T1a and T1b RCC in early follow-up.