MBCL-11. TIME TO RADIOTHERAPY IMPACTS SURVIVAL IN PEDIATRIC AND ADOLESCENT NON-METASTATIC MEDULLOBLASTOMA TREATED BY UPFRONT RADIOTHERAPY – A REPORT FROM THE HIT 2000 TRIAL

PURPOSE: To evaluate prognostic factors and impact of participation in a randomized trial in non-metastatic medulloblastoma. METHODS AND PATIENTS: 382 patients with non-metastatic medulloblastoma aged 4–21 years with primary neurosurgical resections between 2001 and 2011 were enrolled into the HIT 2000 trial and centrally reviewed. Between 2001 and 2006, 176 of these patients participated in the randomized trial HIT-SIOP PNET 4. Three different radiotherapy protocols were applied. Molecular subgroup was available for 157 patients. RESULTS: Median follow-up was 6.35 [0.09–13.86] years. The 5-year progression-free (PFS) and overall survival (OS) rates were 80.3 % ± 2.1 % and 86.5 % ± 1.8 %, respectively. On univariate analysis, there was no difference in PFS and OS according to radiotherapy protocols or in patients who participated in the HIT-SIOP PNET 4 trial or not, while histology, molecular subgroup and postoperative residual tumor influenced PFS significantly. Time interval between surgery and irradiation (≤48 days vs. ≥49 days) failed the significance level (p=0.052). On multivariate analyses, molecular subgroup (WNT activated vs. Group3 HR 5.49; p=0.014) and time interval between surgery and irradiation (HR 2.2; p=0.018) were confirmed as independent risk factors. CONCLUSION: Using a centralized review system, multiprofessional and multiinstitutional collaboration as established for pediatric brain tumor patients in Germany, and risk-stratified therapy, outcome for non-metastatic medulloblastoma treated within HIT-SIOP PNET4 could be maintained outside the randomized trial. Prolonged time to radiotherapy negatively influenced survival.