Statistical analysis

Statistical analysis was performed using the IBM SPSS Statistics 27 (IBM Japan, Tokyo, Japan) or R version 4.3.2 (R Foundation for Statistical Computing, Vienna, Austria). Statistical significance was set at P<0.05. Continuous variables are presented as medians and ranges, and comparisons were conducted using the Mann-Whitney U test. Categorical variables are expressed as numbers and percentages, and comparisons were performed using the χ² test or Fisher's exact test. The OS rate was evaluated using Kaplan-Meier survival curves and the log-rank tests. Cox proportional hazards model analysis was used to estimate hazard ratio (HR) and 95% confidence interval (CI). Significant variables in the univariate analysis were included in the multivariate analysis.