Sample size calculation and statistical analysis

The sample size calculation was based on the assumption that there would be a median overall survival increase of 6 months from TACE treatment alone. A sample size of 28 cases in each group would provide a 90% power to estimate the overall survival improvement at 5% level of significance in this study. Taking into account a possibility of loss to follow-up of 20%, 35 cases were required in each group for this study.

Survival analysis was performed with the log-rank test. Cox proportional hazard regression was utilized to determine hazard ratios (HRs) of factors on survival. Univariate analysis and multivariate analysis were deployed to determine the influence of probable risk factors on survival. Similarly, the odds ratios (ORs) of factors on PES were calculated by logistic regression. Chi-square test was used for evaluating tumour responses. Baseline characteristics were tested using the chi-square or student's test, depending on the type of data. All the statistical work was conducted with SPSS 13.0 software (IBM, Chicago, USA).