Statistical analysis
RECRUITMENT
Intention-to-treat analysis was used to analyze the data. The sample size was calculated using Power and Sample Size Calculations software (Version 3.0, 2009, USA). On the basis of previous study, the current study was estimated to detect an improvement in the median OS of 35 months for the DP group to 20 months for the PF group with a two-sided test with alpha level 0.05 and 80% statistical power. An estimated sample of 182 participants (91 per group) was required. Because recruitment in this trial was slower than expected, we performed an interim analysis in March 2015, after 86 patients had been enrolled. The Kaplan-Meier method was used to estimate survival, and the log-rank test was used to determine significance. It was considered significant only if the P-value was < 0.05 on two sides. Comparing baseline characteristics of the treatment groups was done using the t-test or Mann-Whitney U-test for continuous variables, and the Fisher’s exact test for categorical variables. Statistics were analyzed using SPSS version 19.0.