Limited Margin Radiotherapy for Children and Young Adults with Ewing Sarcoma Achieves High Rates of Local Tumor Control
Mené sur 45 patients pédiatriques ou jeunes adultes atteints d'un sarcome d'Ewing et recevant un traitement multimodal (âge médian : 13 ans ; durée médiane de suivi : 54,5 mois), cet essai de phase II met en évidence l'efficacité, du point de vue du contrôle de la maladie, d'une radiothérapie avec marge d'irradiation limitée (volume tumoral + 1 cm)
Purpose : Determine the rate of local failure (LF) using focal conformal, limited margin radiotherapy (RT) and dose escalation for tumors ≥ 8cm (greatest dimension at diagnosis) in children and young adults with Ewing sarcoma (EWS). Methods and Materials : Eligible patients with EWS were treated on a Phase II institutional trial of focal conformal, limited margin RT using conformal or intensity modulated techniques. The treatment volume incorporated a 1cm constrained margin (CTV1) around the gross tumor. Unresected tumors, <8cm at diagnosis, received a standard dose of 55.8Gy and tumors ≥8cm an escalated dose to 64.8Gy. Patients with microscopic residual disease after resection received adjuvant RT to 50.4Gy. Adjuvant brachytherapy was permitted in selected patients. Results : Forty-five patients were enrolled, 26 with localized and 19 with metastatic disease. Median (range) age, tumor size and follow-up were 13.0 years (2.9-24.7), 9.0cm (2.4–17.0) and 54.5 months (1.9-122.2), respectively. All patients received systemic chemotherapy. The median (range) RT dose for all patients was 56.1Gy (45-65.5). Seventeen patients received adjuvant, 16 standard dose and 12 escalated dose RT. Failures included 1 local, 10 distant and 1 local/distant. The estimated 10-year cumulative incidence of LF was 4.4% ± 3.1%, with no statistical difference seen between RT treatment groups and no local failures in the escalated dose RT treatment group. Conclusions : Treatment with focal conformal, limited margin RT, including dose escalation for larger tumors, provides favorable local tumor control in EWS.