Data Management and Statistical Analysis
Data were collected prospectively and entered by the local center’s data manager into the database POND (Pediatric Oncology Network Database)11 (this database was retired in 2019). Data frozen as of December 31st 2017 are included in this report. The data were reviewed and confirmed by the primary country team and the PI, with constant quality reviews. Abandonment of therapy was defined as failure to return to continue treatment for 4 weeks or more12. Lost to follow-up was defined as 2 years from the end of therapy. Upfront refusals were excluded from the analysis.
Primary outcomes were abandonment-sensitive event-free survival (AS-EFS) and abandonment-sensitive overall survival (AS-OS)13. AS-EFS was defined as the time from date of diagnosis to date of first event (progressive disease, relapse, abandonment, or toxic death) or date of last contact for those who were event-free. AS-OS was calculated as time from diagnosis to abandonment or death, or last contact for those still alive. In addition, EFS and OS rates censoring abandonment, were also calculated. Survival rates were estimated using the Kaplan-Meier method with standard errors of Peto et al14,15 The two-sided log-rank test was used for comparison of survival curves. P-values <0.05 were considered statistically significant for all comparisons. All analyses were performed using SAS® version 9.4. Graphics were generated using R (http://www.R-project.org, version 4.1.1).