Statistical analysis
Overall survival (OS) was defined as the time from diagnosis to the date
of last follow-up or death from any cause. EFS was defined as the time
from diagnosis to the first event (remission failure, relapse, death, or
secondary malignancy) or the last follow-up. Continuous variables were
expressed as medians and ranges, while categorical variables were
expressed as frequencies and percentages. The differences between
different groups were analyzed using a Mann-Whitney U-test or a
Chi-square test for continuous and categorical variables, respectively.
OS and EFS were analyzed using the Kaplan-Meier method and a log-rank
test. Cox regression analysis was performed using a multivariate
analysis. Statistical analysis was performed using SPSS software
(version 22.0; IBM, Armonk, NY). A P value of < 0.05
was considered statistically significant.