title: Differential attenuation of clavicle growth after asymmetric mantle radiotherapy.
abstract: OBJECTIVE
  To determine the effects of 15 Gy on bone growth as a function of time and age by comparing clavicle length before and after asymmetric mantle irradiation in pediatric patients.
  
  
  METHODS
  We measured the lengths of both clavicles from radiographs made before and after radiotherapy (median follow-up, 39.6 months), in 15 children (median age, 13.3 years) with early-stage Hodgkin's disease treated with combined modality therapy. The intercepts and slopes of regression lines for individual patients were used to form an estimating regression curve for the population.
  
  
  RESULTS
  The irradiated volume, patient age, and time elapsed after treatment influenced the measured growth. Fully irradiated clavicles grew 1.3 +/- 0.3 cm, significantly less (0.5 cm; p = 0.007) than did the partially irradiated clavicles. The difference between partially and fully irradiated clavicle lengths was statistically significant, regardless of age. Also, the growth rate of partially and fully irradiated clavicles was significantly different between younger (mean age, 9.9 years) and older (mean age, 16.4 years) patients (p = 0.036).
  
  
  CONCLUSIONS
  Clavicle growth is vulnerable to radiation doses as low as 15 Gy, and patient age at the time of irradiation influences the growth rate.
authors.affiliation: Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA. thomas.merchant@stjude.org
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Merchant
authors.forename: Lan
authors.initials: L
authors.lastname: Nguyen
authors.forename: Duyen
authors.initials: D
authors.lastname: Nguyen
authors.forename: Shengje
authors.initials: S
authors.lastname: Wu
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Hudson
authors.forename: Sue C
authors.initials: SC
authors.lastname: Kaste
mesh_terms: D000016:Abnormalities, Radiation-Induced / Q000209:etiology*; D000293:Adolescent; D000367:Age Factors; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D002968:Clavicle / Q000002:abnormalities / Q000254:growth & development / Q000528:radiation effects*; D003131:Combined Modality Therapy; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006689:Hodgkin Disease / Q000188:drug therapy / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000008:administration & dosage; D011241:Prednisone / Q000008:administration & dosage; D011829:Radiation Dosage; D012189:Retrospective Studies; D014747:Vinblastine / Q000008:administration & dosage
chemical_list: D014747:Vinblastine; D004317:Doxorubicin; D011241:Prednisone; D008727:Methotrexate