Thyroid dysfunction as a late effect in survivors of pediatric medulloblastoma/primitive neuroectodermal tumors: a comparison of hyperfractionated versus conventional radiotherapy.
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.
Chin
D
D
Division of Pediatric Endocrinology, New York University Medical Center, New York 10016, USA.
Sklar
C
C
Donahue
B
B
Uli
N
N
Geneiser
N
N
Allen
J
J
Nirenberg
A
A
David
R
R
Kohn
B
B
Oberfield
S E
SE
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