Case Report Radio-frequency ablation of hepatocellular carcinoma before liver transplantation: a histologic and ‘TUNEL’ study G. J. Netto 1 , B. Altrabulsi 1 , N. Katabi 1 , P. Martin 2 , K. Burt 1 , M. Levy 2 , E. Sanchez 2 , D. L. Watkins 1 , L. Jennings 1 , G. Klintmalm 2 and R. Goldstein 2 Departments of 1 Pathology and 2 The Baylor Regional Institute of Transplantation, Baylor University Medical Centre, Dallas, TX, USA Netto GJ, Altrabusi B, Katabi N, Martin P, Burt K, Levy M, Sanchez E, Watkins DL, Jennings L, Klintmalm G and Goldstein R. Radio-frequency ablation of hepatocellular carcinoma before liver transplantation: a histologic and ‘TUNEL’ study. Liver International 2006: 26: 746–751. r 2006 The Authors. Journal compilationr 2006 Blackwell Munksgaard Abstract: Background: Radio-frequency ablation (RFA) is an increasingly used treatment modality for hepatocellular carcinoma (HCC) in patients awaiting liver transplantation (OLTX). The current study evaluates the effectiveness of RFA in this setting based on evaluation of total cell death in explanted native livers. Design: We evaluated 36 tumors from 35 patients with RFA-treated HCC who underwent OLTX at our center between 1998 and 2002. Native livers from OLTX were extensively sampled for histologic evaluation. For each HCC, an estimate ratio of necrotic tumor areas was calculated based on hematoxylin and eosin (H&E) sections. In tumors with 10% or more residual viable areas, Tdt-mediated UTP nick-end labeling (TUNEL) was further performed to assess apoptosis in the morphologically ‘viable’ areas. A final ‘tumor cell death’ (TCD) ratio was recalculated for each HCC to include areas of apoptosis identified by TUNEL. Results: Based on H&E evaluation, 22/36 (61.1%) HCC revealed  90% necrosis including 12/ 36 HCC (33.3%) showing no evidence of residual viable tumor. The overall median tumor necrosis was 79%. When TUNEL findings were added, 26/36 (72.2%) HCC revealed  90% TCD including 14/36 HCC (38.8%) showing complete TCD (median TCD of 88.4%). None of our patients died of HCC while awaiting OLTX. Longer RFA-to-transplant time appears to be associated with a higher TCD rate (median of 154.5 days in patients with less than 90% TCD vs 326 days for patients with  90% TCD; P 5 0.019). There was no significant correlation between tumor grade or pre-RFA size of the tumors and TCD rate in RFA-treated HCC (P 5 0.11). Conclusion: Extensive TCD (88.4% median) can be obtained using RFA for HCC in patients awaiting OLTX. Our TUNEL findings suggest that RFA- induced cell injury could be associated with apoptosis. Keywords: apoptosis – RFA-hepatoma – TUNEL G. J. Netto, Department of Pathology, Johns Hopkins University, 402 N. Broadway, Weinberg Building/Room 2242, Baltimore, MD 21231, USA. e-mail: gnetto1@jhmi.edu Received 30 January 2006, accepted 20 March 2006                                                                                                               The estimated worldwide prevalence of hepato- cellular carcinoma (HCC) is 500 000–1 million cases. HCC accounts for 90% of primary hepatic malignancies. The incidence of HCC is rising in the western hemisphere and Asia mainly because of the increasing prevalence of chronic viral hepatitis C-induced cirrhosis (1–3). Currently, under the widely accepted ‘Milano criteria’ (4), patients with a single HCC tumor smaller than 5 cm, and those with up to three HCC tumors each smaller than 3 cm, are maintained on OLTX waiting list. In many centers however, waiting-list periods are on the rise making pretransplant ablation of such lesions of utmost utility. Several treatment modalities are currently in use in this setting to include percutaneous ethanol (ETOH) injection, trans-catheter arterial chemo-emboliza- tion, and radio-frequency ablation (RFA) (5, 6). RFA is accomplished by applying electrical energy that generates frictional heat among tu- mor molecules. The generated heat leads to cell death and ultimately widespread destruction of the tumor mass. RFA can be applied using small electrodes and under real-time imaging guidance allowing for selective destruction of tumor areas with only minimal injury to the surrounding non- Liver International 2006: 26: 746–751 r 2006 The Authors Journal compilation r 2006 Blackwell Munksgaard DOI: 10.1111/j.1478-3231.2006.01278.x 746