Analysis and Sample Size
A minimum number of patients is typically required for individual study. We compared the number of patients required in the WR vs the number actually enrolled to fulfill the WR when the WR is completed. Eight pediatric trials in WRs for solid tumors and 2 pediatric trials in WRs for hematologic malignancies recruited less patients than requested; while 3 pediatric trial for solid tumor and 3 pediatric trials for hematologic malignancies recruited more patients than requested.