Limitations of this study
The small number of study reports available for references in the design of this study made it difficult to estimate the number of relapses and to determine the necessary number of patients to enroll. Although this study suggested that ESC had a relapse-prevention effect, there was no statistically significant difference in the primary analysis (log-rank test for time to relapse) due to the lower relapse rate and lower power than expected. A repeat of this study that includes more patients might verify the relapse-prevention effect of ESC.