Statistical analysis
All statistical analyses were performed using the SPSS (version 25, Chicago, NY, USA) and R software (version 3.6.2, http://www.Rproject.org). Data were expressed as counts (percentages) for categorical variables, as mean ± standard deviation (SD) for quantitative variables according to normal distribution, and as median (range) for variables with non-normal distribution. Pearson χ² tests or Fisher’s exact tests were used to analyse relationships between categorical variables. PFS was performed using the Kaplan-Meier method. Univariate analyses were performed with the log-rank test, and variables with a P value lower than 0.1 were included in the multivariate analysis. Multivariate analyses were performed using the Cox’s proportional hazard regression model. Statistical significance was set at P < 0.05.