DIPG-28. REPEATED LOW DOSE RT FOR PEDIATRIC DIPG – LESS DISEASE BURDEN WITH COMPARABLE OUTCOMES

PURPOSE: Pediatric diffuse intrinsic pontine glioma (DIPG) is the most dismal prognosis pediatric brain tumor. Six weeks radiation therapy (RT) remains the mainstay of treatment. The aim of the current study was to compare the results of firstly reported repeated low dose RT (rLRT) with conventional RT (CRT). METHODS AND MATERIALS: This retrospective review included 24 children with DIPG, aged 3 -18 years, underwent CRT (52- 60.0 Gy in 1.8- 2.0 Gy, n = 16) or rLRT (18 - 30 Gy in 1.5–2.0 Gy per cycle for 1–3 cycles, n = 8). All children had typical symptoms and MRI features of DIPG, or biopsy-proven DIPG. RESULTS: The median overall survival (OS) was 12.6 months in rLRT group and 11.4 months in CRT group (p =0.347), progression-free survival (PFS) was 3.6 months in rLRT group and 6.5 months in CRT group (p = 0.821), no significant survival difference was observed between two groups. Temporary discontinuation or tapering of steroids rate was significantly higher in rLRT group (100% vs 60%, p = 0.028). Although not statistically significant, mean non-hospitalized days were longer in the rLRT group, 403 days versus 305 days in the CRT group, as were mean cumulative progression-free days, 276 days versus 163 days and 1-year free from CSF diversion rate was higher, 100% versus 64.9%. CONCLUSIONS: For patients with newly diagnosed DIPG, repeated low dose RT, given over 3 to 4 weeks per cycle for 1 to 3 cycles, offers comparable survival outcome with less disease burden compared with conventional RT.