Statistical analysis
Baseline data were compared using the chi-square test. OS and 5-year DFS
were estimated by the Kaplan-Meier method. Prognostic factors were
assessed in univariate analysis using the log-rank test and in
multivariate analysis using Cox models. Statistical calculations were
performed using SPSS (version 23.0; SPSS, Inc. an IBM Company, Chicago,
Illinois). The VHI-30 scores of the two groups were compared using the
Mann-Whitney U test. P value less than 0.05 was defined as statistically
significant.