4.0 Statistical Consideration 4.1 Sample size Review of literatures showed that the 2-year survival rate of post-operative HCC was 25% to 60% [7-14]. We estimate that adjuvant IFN-α can improve the 2-year survival rate from 50% to 70%. According to the methods of Casagrande et al.[129], to give a 90% power for detecting the increase of 20% for a two-sided statistical significance test, 134 patients for each of the two treatment arms are needed. 4.2 Randomization Patients are stratified into two strata : one with HBsAg(+),another with HBsAg(-) but with anti-HCV(+). Randomization of patients into control or treatment group is taken within each stratum. Balanced block sizes of two strata for randomization are different. 4.3 Analysis 4.31 The primary objectives are as follows: 4.311 To determine if adjuvant IFN-α can reduce or delay the occurrence in curatively resected HCC. 4.312 To determine if adjuvant IFN-α prolong disease-free survival (DFS) and/or overall survival (OS) in curatively resected HCC. 4.313 To determine the safety and tolerance of IFN-αin post-operative H.C.C patients. 4.314 To evaluate the anti-viral activity of IFN-α in post-operative HCC patients. 4.32 DFS and OS are computed from the date of randomization. 4.321 In analysis of DFS, patients died without disease recurrence will be censored for recurrence at the date of death. 4.322 In analysis of OS, an event is defined as death from any cause. 4.323 The survival distributions of DFS and OS will be estimated by the Kaplan and Meier method [130]. 4 4.324 Statistical comparisons of DFS and OS between the two treatment arms will be performed with the log-rank statistic [131]. 4.325 Cox proportional hazards model [132] will be used to assess the importance of potential prognostic factors, as well as to test the significance of treatment when adjusting for factors. 4.33 Tumor size, Liver inflammation, viral status such as HBsAg. anti- HCVand