Radt-06. Encouraging Outcomes After Cranio-Spinal Irradiation (Csi) With Modern Image Guided Intensity Modulated Proton Therapy (Impt) (Impt-Csi) in Children and Young Adults (Aya)- An Institution Experience

Abstract BACKGROUND Outcomes of IMPT-CSI in children and adolescent-young adults (AYA) treated at our institute over a period of 5 years was analyzed MATERIALS AND METHODS 92 children/AYA were treated by IMPT-CSI. PTV definition of the spine for skeletally immature patients was modified to only the vertebral body without isotropic margins. All plans were multifield optimized for 5 mm robustness (cranio-caudal) 97%. Isodose 95% covered the cribriform plate completely and optic nerves keeping Dmax to the lens 3.9 GyRBE, critical OARs (mean of the cohort- Cochlea Dmax 28GyE, midline mucosa 23.2GyE, Esophagus 23.2GyE and gonads (testes and ovaries- 0GyE and 0.4GyE). The online set-up verification showed translational and rotational deviation within 2 mm and 0.5 in 94% and 97% of the cases. Radiation dermatitis was Grade 2-40%; Gr3-10%. Neutropenia was Grade 3 in 30%; few needed G-CSF. Less than 10% developed grade 3 significant weight loss/ anorexia/ mucositis. At median F/U 20 months (6–60m), 12 patients have progressed with PFS of 78% 0.014) CONCLUSION Outcomes of IMPT-CSI in children and young adults, showed very encouraging dosimetry, toxicity profile and long-term survival.