Spss statistical software program version 17

The χ2 test or Fisher's exact test was used appropriately to analyze the relationship between NOTCH4 expression and clinicopathological variables. Multiple comparisons between groups were determined using Bonferroni's correction with type I error adjustment. For OS analysis, patients who died at the last follow-up were defined as clinical endpoints. For analysis of DFS, tumor progression after surgical resection was the clinical endpoint, documented as either tumor recurrence or metastasis. Follow-up data were recorded by phone or medical records. The survival rates were calculated by the Kaplan-Meier method and the differences between the survival curves were examined by the log-rank test. Univariate Cox proportional hazards regressions were applied to estimate the individual hazard ratio (HR) for the DFS and OS. The significant variables in the univariate analyses (P<0.05) were then put into the multivariate analysis. The HR with 95% confidence interval (CI) was measured to estimate the hazard risk of individual factors. A two-sided P-value of <0.05 was considered to indicate statistical significance. Analyses were performed using the SPSS statistical software program version 17.0 (SPSS Inc., Chicago, IL).