Degree of Kidney Tumor Enhancement Predicts Radiofrequency Ablation Failure
Aaron Lay, Noah Canvasser, Jeremy Stewart, Jeffrey Cadeddu, Jeffrey Gahan
Radiofrequency ablation (RFA) is a minimally invasive technique to treat small renal masses. RFA failure is associated with tumor size and tumor histology, with larger size and clear cell histopathology on biopsy associated with higher rates of RFA failure. Dr. Canvasser’s team reported a study with the hypothesize that kidney tumors that enhance greatly on contrast imaging may be at higher risk for RFA failure due to its vascularity.
Authors performed a retrospective review of patients who underwent RFA for kidney tumors at their institution from 2005 to 2014. A computed tomography (CT) scan with and without contrast pre-procedure must be available to be included in the analysis. Authors defined RFA failure as incomplete ablation defined on initial imaging. The change in Hounsfield units (HU) of the tumor from the non-contrast phase and the contrast-enhanced phase was recorded.
The study included a total of 158 patients with pre-procedure contrast enhanced CT scans. RFA failure rate was significantly less for tumors that enhance <60 HU vs. ≥60 HU (1.2% vs. 9.5%, p=0.018). RFA failure rate is not significantly different in tumors with size <3cm vs. ≥ 3cm, NS <6 vs. NS ≥ 6, and clear cell vs. non-clear cell type. On multivariate logistic regression analysis, tumor enhancement ≥60 HU (OR 1.10, p=0.013) remained significant predictor for RFA failure. 5 year DFS for size <3cm was 100% vs. 74.3% for size ≥3cm, p<0.01. 5 year DFS for HU change <60 was 86.7% compared to 94.8% for HU change ≥60, p=0.71. 5 year DFS for non-clear cell tumors was 100% vs. 86.3% for clear cell tumors, p=0.02.
Authors concluded that kidney tumor enhancement of ≥60 HU predicts higher rate of RFA failure.
Presented by Noah Canvasseh at the 2015 World Congress of Endourology Annual Meeting – October 1-4, 2015, London, United Kingdom.
Written by Zhamshid Okhunov for UroToday.com.