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.