Intensity modulated radiotherapy (IMRT) and fractionated stereotactic radiotherapy (FSRT) for children with head-and-neck rhabdomyosarcoma

Abstract

9065 Background: To evaluate intensity-modulated radiotherapy (IMRT) and fractionated stereotactic radiotherapy (FSRT) for children with head-and-neck rhabdomyosarcoma (RMS) with special regard to radiation induced toxicity. Methods: From 1995 to 2005, we treated 19 children with head-and-neck RMS with FSRT (n=14) or IMRT (n=5). The median age at the time of RT was 62.5 months. All children received systemic chemotherapy according to the German Soft Tissue Sarcoma Study protocols (CWS). Patients were grouped classified according to the grouping system used in Intergroup Rhabdomyosarcoma Study Group (IRSG) trials. Patients were immobilized using an individual mask fixation system. For treatment planning contrast-enhanced MRI- and CT-scans were performed. Median size of PTV for RT was 93,4 ml. We applied a median total dose of 45 Gy (range 32 - 54 Gy) using a median fractionation of 5 × 1,8 Gy/week (range 1,6 - 1,8 Gy / week). Deep sedation or general anaesthesia was required for children < 5 years. Results: RT was well tolerated in all children and could be completed without interruptions > 4 days. Minor RT-induced side effects included skin erythema, alopecia, conjunctivitis, mucositis and nausea / vomiting, however no toxicities >CTC grade II developed. The median follow-up time after precision RT was 17 months. Until now, no secondary malignancies developed. After RT, the 3- and 5-year survival rate was 94%. The 3- and 5-year actuarial local control rate after RT was 89%. With respect to tumor localization, the 3- and 5-year local control rates were 100% for patients with RMS of the orbit and 91% for patients with parameningeal tumors. The actuarial freedom of distant metastases rate was 89% at 5 years. For patients with RMS of the orbit only, the actuarial distant progression-free survival rate was 100% at 5 years. The actuarial 3- and 5-year distant metastases-free survival rate was 91%, in children with parameningeal RMS. Conclusions: High precision RT techniques such as IMRT and FSRT offer good coverage of complex shaped target volumes in critical locations with the necessary RT dose while adhering to the tolerance doses of nearby critical normal tissue structures. Local and distant control rates are not reduced. No significant financial relationships to disclose.