2. Statistical analysis

Categorical variables were described using counts and frequencies, and quantitative variables were described using medians and ranges. Patients' characteristics according to periods and complete resection were compared using χ² test or Fischer test. Quantitative values were compared using t-test. Significant factors associated with stoma and complications were determined using binary logistic regressions. Comparisons of survival results were analyzed with Log-rank test and multivariate Cox regression model. The level of statistical significance was set at α=0.05. Statistical analyses were carried out with the SPSS® software version 16 (Chicago, IL, USA).