title: A dosimetric comparison of proton and intensity modulated radiation therapy in pediatric rhabdomyosarcoma patients enrolled on a prospective phase II proton study.
abstract: BACKGROUND
  Pediatric rhabdomyosarcoma (RMS) is highly curable, however, cure may come with significant radiation related toxicity in developing tissues. Proton therapy (PT) can spare excess dose to normal structures, potentially reducing the incidence of adverse effects.
  
  
  METHODS
  Between 2005 and 2012, 54 patients were enrolled on a prospective multi-institutional phase II trial using PT in pediatric RMS. As part of the protocol, intensity modulated radiation therapy (IMRT) plans were generated for comparison with clinical PT plans.
  
  
  RESULTS
  Target coverage was comparable between PT and IMRT plans with a mean CTV V95 of 100% for both modalities (p=0.82). However, mean integral dose was 1.8 times higher for IMRT (range 1.0-4.9). By site, mean integral dose for IMRT was 1.8 times higher for H&N (p<0.01) and GU (p=0.02), 2.0 times higher for trunk/extremity (p<0.01), and 3.5 times higher for orbit (p<0.01) compared to PT. Significant sparing was seen with PT in 26 of 30 critical structures assessed for orbital, head and neck, pelvic, and trunk/extremity patients.
  
  
  CONCLUSIONS
  Proton radiation lowers integral dose and improves normal tissue sparing when compared to IMRT for pediatric RMS. Correlation with clinical outcomes is necessary once mature long-term toxicity data are available.
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Ladra
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Samantha K
authors.initials: SK
authors.lastname: Edgington
authors.affiliation: The University of Texas MD Anderson Cancer Center, Houston, USA.
authors.forename: Anita
authors.initials: A
authors.lastname: Mahajan
authors.affiliation: The University of Texas MD Anderson Cancer Center, Houston, USA.
authors.forename: David
authors.initials: D
authors.lastname: Grosshans
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Jackie
authors.initials: J
authors.lastname: Szymonifka
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Fazal
authors.initials: F
authors.lastname: Khan
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Maryam
authors.initials: M
authors.lastname: Moteabbed
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Friedmann
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: MacDonald
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Tarbell
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, USA. Electronic address: tyock@partners.org.
authors.forename: Torunn I
authors.initials: TI
authors.lastname: Yock
mesh_terms: D002648:Child; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D059351:Organ Sparing Treatments / Q000379:methods; D010386:Pelvic Neoplasms / Q000532:radiotherapy*; D011446:Prospective Studies; D061766:Proton Therapy / Q000379:methods*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012208:Rhabdomyosarcoma / Q000532:radiotherapy*; D013899:Thoracic Neoplasms / Q000532:radiotherapy*
keywords: Pediatrics; Protons; Rhabdomyosarcoma