Statistical analyses
Descriptive statistics were calculated for the baseline demographic and clinical features and treatment outcomes. Graphical and mathematical methods tested the normality of distribution. As appropriate, continuous variables were presented as means with standard deviations or medians with 25th-75th percentiles. Categorical variables were presented as numbers and percentages. Differences between groups were analysed using Student’s t-test for continuous variables (or the Mann-Whitney test) and the Pearson chi-squared test for categorical variables. Survival analysis was performed using the Kaplan-Meier method, and the groups were compared using the log-rank test. In addition, Kaplan-Meier survival curves were truncated at a timepoint in follow-up, when at least 10% of patients were still at risk, to avoid visual misinterpretation.(13) The significance level was set at 0.05, and all testing was two-sided. Statistical analysis was performed using the IBM SPSS Statistics for Windows, version 21.0. (Armonk, NY, USA) package.