Postoperative spot-scanning proton radiation therapy for chordoma and chondrosarcoma in children and adolescents: initial experience at paul scherrer institute.

Abstract

To evaluate postoperative spot-scanning proton radiation therapy (PT) and intensity-modulated PT (IMPT) for chordoma and chondrosarcoma in pediatric patients. Between 2000 and 2005, 10 patients (six male patients, four female patients; six chordomas, four chondrosarcomas), aged 10-20 years (median, 16 years), were treated at our institute. Tumor sites were in the brain (one case), skull base (five cases), cervical (three cases), and lumbar spine (one case). Three children had complete resections. In seven children, resection was incomplete, leaving residual tumor behind (range, 2.3-46.3 mL). PT was delivered using spot scanning, with (three patients) or without (seven patients) IMPT. Total dose was 74.0 cobalt Gray equivalents (CGE) for chordoma, and 63.2-68.0 CGE for chondrosarcoma (median, 66.0), depending on histopathological grading and whether the patient had concurrent chemotherapy. Median follow-up time was 36 months (range, 8-77 months). Radiation treatment was well tolerated. All patients remained failure-free at their last follow-up. Late adverse events were reported in three patients and were mild (neurosensory in one patient; alopecia and hypoaccusis in one patient) to moderate (one patient, Grade 2 pituitary insufficiency). Postoperative spot-scanning PT, delivered in combination with and without IMPT, for chordoma and chondrosarcoma in children and adolescents was tolerated without unacceptable adverse event and initial outcome is perfectly satisfactory in this small cohort. Longer follow-up time and larger cohort are needed to more fully assess tumor control, adverse events, as well as functional and cosmetic outcome.