title: Thyroid dysfunction as a late effect in survivors of pediatric medulloblastoma/primitive neuroectodermal tumors: a comparison of hyperfractionated versus conventional radiotherapy.
abstract: BACKGROUND
  Primary hypothyroidism is a common sequela of craniospinal radiotherapy in the treatment of pediatric brain tumors.
  
  
  METHODS
  The authors compared the incidence of primary hypothyroidism after hyperfractionated radiotherapy (HFRT) (n = 14 patients) versus conventionally fractionated radiotherapy (CRT) (n = 34 patients) in a group of pediatric patients with medulloblastoma/primitive neuroectodermal tumors (MB/PNET).
  
  
  RESULTS
  The mean age at the time of tumor diagnosis was 7.9 years in the HFRT group and 8.4 years in the CRT group. The patients were followed for a mean of 4.6 years (HFRT) and 8.3 years (CRT) after diagnosis. Mean radiation doses to the thyroid were similar in both radiotherapy groups (29 gray [Gy] [HFRT] vs. 24 Gy [CRT]). Approximately 14% of the HFRT and 62% of the CRT patients developed primary hypothyroidism within a similar period after irradiation (3.2 years [HFRT] vs. 3.0 years [CRT]). Analysis by cumulative incidence function demonstrated a significant difference in the risk of developing thyroid dysfunction between these two groups of patients (P = 0.02).
  
  
  CONCLUSIONS
  The current study findings suggest that the use of HFRT in the treatment of pediatric patients with MB/PNET is associated with a lower risk of these patients developing primary hypothyroidism.
authors.affiliation: Division of Pediatric Endocrinology, New York University Medical Center, New York 10016, USA.
authors.forename: D
authors.initials: D
authors.lastname: Chin
authors.forename: C
authors.initials: C
authors.lastname: Sklar
authors.forename: B
authors.initials: B
authors.lastname: Donahue
authors.forename: N
authors.initials: N
authors.lastname: Uli
authors.forename: N
authors.initials: N
authors.lastname: Geneiser
authors.forename: J
authors.initials: J
authors.lastname: Allen
authors.forename: A
authors.initials: A
authors.lastname: Nirenberg
authors.forename: R
authors.initials: R
authors.lastname: David
authors.forename: B
authors.initials: B
authors.lastname: Kohn
authors.forename: S E
authors.initials: SE
authors.lastname: Oberfield
mesh_terms: D000293:Adolescent; D001932:Brain Neoplasms / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology*; D008297:Male; D008527:Medulloblastoma / Q000532:radiotherapy*; D018242:Neuroectodermal Tumors, Primitive / Q000532:radiotherapy*; D011832:Radiation Injuries; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods; D011879:Radiotherapy Dosage; D013997:Time Factors