Ablation Difficulty Score: Proposal of a new tool to predict success rate of percutaneous ablation for hepatocarcinoma

PurposeIdentify the factors related to failure ablation after percutaneous ultrasound guided single electrode radiofrequency ablation (RFA) for hepatocarcinoma (HCC) and propose a score for improving patient selection and treatment allocation.MethodsFrom 2010 to 2020 585 HCC nodules treated with RFA were prospectively collected. Ablation Difficulty Score (ADS) was built-up according to clinical and radiological factors related to failure ablation identified by Cox-logistic regression analysis. The study population was stratified in low risk (ADS 0), intermediate risk (ADS 1), and high risk (ADS ≥ 2) of failure ablation.ResultsOverall ablation success rate was 85.5%. Morbidity and mortality rates were 3.5% and 0.0%. According to per nodule analysis the following factors resulted related to failure ablation: size > 20 mm (p = 0.002), sub-capsular location (p = 0.008), perivascular location (p = 0.024), isoechoic appearance (p = 0.008), and non-cirrhotic liver (p = 0.009). The ablation success rate was 93.5% in ADS 0, 85.8% in ADS 1 and 71.3% in ADS ≥ 2 (p < 0.001). The 1-year local tumor progression (LTP) free survival was 90.2% in ADS 0, 80.6% in ADS 1, and 72.3% in ADS ≥ 2 (p = 0.009). Nodule's size > 20 mm (p = 0.014), isoechoic appearance (p = 0.012), perivascular location (p = 0.012) resulted related to lower LTP free survival.ConclusionAblation Difficulty Score could be a simple and useful tool for guiding the treatment decision making of HCC. RFA in high risk nodules (ADS ≥ 2) should be carefully evaluated and reserved for patients not suitable for surgery or liver transplantation.