HCC,7,8 but a shortage of liver grafts limits the applicability of this approach. Radiofrequency ablation (RFA) is a minimally invasive technique as a curative treatment modality for HCC. It is well- tolerated in HCC patients with advanced cirrhosis, with low mor- bidity rate ranging from 0% to 28% and peri-operative mortality rate of 0% to 2%.9,10 A recent randomized controlled trial also suggested that percutaneous RFA was as effective as hepatic re- section in terms of overall survivals in selected patients.11 Despite its technical simplicity and safety, deterioration of liver function is inevitable after RFA.12 Furthermore, the recurrence rate of HCC af- ter RFA is not negligible ranging from 49% to 74% in 5 years.13,14 Thus, maintaining residual liver function reservoir is very impor- tant to treat recurrent HCC appropriately. Although RFA is widely performed in clinical practice, there is little knowledge in changes of residual liver function in patients after RFA. In this study, we evaluated changes in liver function parameters after RFA therapy and identified risk factors for aggravation of liver function. PATIENTS AND METHODS Patients Between January 2005 and December 2008, 651 patients with HCC were treated in Kyungpook National University Hospital. Of those patients, we included 102 patients diagnosed as HCC with underlying cirrhosis, who had complete ablation without recur- rence for 12 months after RFA, and did not receive any other ther- apies such as surgical resection, transarterial chemoembolization (TACE) and radiotherapy. Exclusion criteria included patients with previous treatment for HCC, follow-up loss after RFA, and any therapies which can influence liver function parameters such as albumin infusion and therapeutic paracentesis. Anti-viral therapies in patients with chronic hepatitis B were permitted. Patients who had abnormal liver function test due to drug resistance excluded. Diagnosis of liver cirrhosis were made by either presence of esophageal varix, or radiologic evidences of cirrhosis including surface nodularity and splenomegaly. Diagnosis of HCC was based on the American Association for the Study of Liver Diseases prac- tice guidelines on the management of HCC in 2005. Techniques of RFA Cool-tipTM Radiofrequency Ablation system (Valleylab, USA) was used for RFA. The ablation was performed using an automatic Hyun Seok Lee, et al. Liver function deterioration after radiofrequency ablation impedance control mode in which the current output was auto- matically adjusted according to the impedance at the needle tip. For large tumors, multiple overlapping ablations were performed. All ablations aimed at achieving ablation of 1 cm margin of non- tumorous liver parenchyma in a single RFA session. Data collection and follow up Clinical data and treatment outcomes of all patients were ret- rospectively collected in a computerized database. The treatment protocol and data collection were approved by the institutional review board. To confirm complete ablation, abdominal dynamic computed tomogram (CT) scan was performed 1 month after RFA. All patients underwent serial monitoring of alpha-fetoprotein (AFP) and dynamic CT scan at 3 month intervals for detection of local recurrence, distal intrahepatic recurrence and extrahepatic metas- tasis. Liver function test along with complete blood count test and prothrombin time (PT), were measured and Child–Pugh score was calculated before RFA and 1, 3, 6, 12 months after RFA therapy. Analysis of risk factors for aggravation of liver function Deterioration of liver function after RFA therapy was defined as an increase in Child-Pugh score by 2 or more at 12 months after RFA therapy. Patients with deteriorated liver function and those with well-preserved liver function after RFA were compared in relation to 16 clinical variables that potentially represent changes of liver function. These included 11 host-related factors (gender, age, hepatitis B surface antigen status, hepatitis C antibody sta- tus, Child–Pugh classification, Child-Pugh score, pre-RFA albumin, pre-RFA total bilirubin, pre-RFA platelet count, pre-RFA alanine aminotrasferase (ALT), pre-RFA PT), and 5 tumor-related factors (pre-RFA AFP, size of tumor, number of tumor, ablation time, num- ber of ablation). Statistics Laboratory data are shown as mean±standard error and range. Comparison of variables after RFA (3, 6, 12 months) was performed using the repeated measured ANOVA. Risk factors for deterioration of liver function were analyzed by Cox proportional hazards regression model. Parameters identified as significant in univariate analysis were tested in the multivariate analysis. P <0.05 was considered to be significant. Data processing and analysis http://www.e-cmh.org http://dx.doi.org/10.3350/cmh.2012.18.3.302 303