Reirradiation of Recurrent Pediatric Brain Tumors after Initial Proton Therapy

Abstract Purpose: The use of reirradiation for recurrent pediatric brain tumors has been increasing, but the effect of repeat radiation on critical cranial structures is unknown. Methods and Materials: Between July 2009 and May 2013, the records of 12 pediatric patients initially treated with proton therapy and then with reirradiation for recurrent brain tumors were retrospectively reviewed for toxicity and outcomes. Initial and repeat radiation dose distributions were deformed and merged to determine the maximum dose to 0.03 cm3 of the optic chiasm, optic nerves, spinal cord, brainstem, cochleae, pituitary, and uninvolved brain, and to 1 cm3 of the brainstem and brain on individual and composite plans. These dosimetric results were compared with auditory, neurocognitive, ophthalmologic, and endocrine outcomes to identify radiation-associated toxicities. Results: Median follow-up was 3.5 years from diagnosis. Median ages at initial and repeat radiation were 4.6 and 6.7 years, respectively. All patients in...