Statistical analysis

The data were presented as the mean ± SEM. Student’s t test and the chi-square test were used for comparisons between two independent groups, and one-way ANOVA was used to compare differences among more than two groups. Data analysis was performed using GraphPad Prism 7.0 (La Jolla, CA, USA) and SPSS 21.0 (Abbott Laboratories, Chicago, IL, USA). Pearson’s correlation coefficient analysis was used to determine correlations. Survival curves were plotted using the results of Kaplan-Meier analysis, and disease-free survival was defined as the time from the date of diagnosis to the time of progression/death or the last follow-up. p <0.05 was defined as statistically significant.26