Limited Margin Radiation Therapy for Children and Young Adults With Ewing Sarcoma Achieves High Rates of Local Tumor Control.
To determine the rate of local failure using focal conformal, limited margin radiation therapy (RT) and dose escalation for tumors ≥8 cm (greatest dimension at diagnosis) in children and young adults with Ewing sarcoma (EWS).



Eligible patients with EWS were treated on a phase 2 institutional trial of focal conformal, limited margin RT using conformal or intensity modulated techniques. The treatment volume incorporated a 1-cm constrained margin around the gross tumor. Unresected tumors, <8 cm at diagnosis, received a standard dose of 55.8 Gy and tumors ≥8 cm, an escalated dose to 64.8 Gy. Patients with microscopic residual disease after resection received adjuvant RT to 50.4 Gy. Adjuvant brachytherapy was permitted in selected patients.



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 years), 9.0 cm (2.4-17.0 cm), and 54.5 months (1.9-122.2 months), respectively. All patients received systemic chemotherapy. The median (range) RT dose for all patients was 56.1 Gy (45-65.5 Gy). 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 local failure 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.



Treatment with focal conformal, limited margin RT, including dose escalation for larger tumors, provides favorable local tumor control in EWS.
Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee.
Aimee C
AC
Talleur
Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee.
Fariba
F
Navid
Department of Pediatrics, Stanford University School of Medicine, Stanford, California.
Sheri L
SL
Spunt
Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, Tennessee.
M Beth
MB
McCarville
Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee.
John
J
Wu
Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee.
Shenghua
S
Mao
Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennessee; Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
Andrew M
AM
Davidoff
Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennessee.
Michael D
MD
Neel
Department of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee. Electronic address: matthew.krasin@stjude.org.
Matthew J
MJ
Krasin
D000293:Adolescent; D001859:Bone Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D000072662:Margins of Excision; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000517:prevention & control*; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods; D012512:Sarcoma, Ewing / Q000473:pathology* / Q000532:radiotherapy*; D016896:Treatment Outcome; D055815:Young Adult