Modeling radiation dosimetry to predict cognitive outcomes in pediatric patients with CNS embryonal tumors including medulloblastoma.
OBJECTIVE
Model the effects of radiation dosimetry on IQ among pediatric patients with central nervous system (CNS) tumors.


METHODS
Pediatric patients with CNS embryonal tumors (n = 39) were prospectively evaluated with serial cognitive testing, before and after treatment with postoperative, risk-adapted craniospinal irradiation (CSI) and conformal primary-site irradiation, followed by chemotherapy. Differential dose-volume data for 5 brain volumes (total brain, supratentorial brain, infratentorial brain, and left and right temporal lobes) were correlated with IQ after surgery and at follow-up by use of linear regression.


RESULTS
When the dose distribution was partitioned into 2 levels, both had a significantly negative effect on longitudinal IQ across all 5 brain volumes. When the dose distribution was partitioned into 3 levels (low, medium, and high), exposure to the supratentorial brain appeared to have the most significant impact. For most models, each Gy of exposure had a similar effect on IQ decline, regardless of dose level.


CONCLUSIONS
Our results suggest that radiation dosimetry data from 5 brain volumes can be used to predict decline in longitudinal IQ. Despite measures to reduce radiation dose and treatment volume, the volume that receives the highest dose continues to have the greatest effect, which supports current volume-reduction efforts.
Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
Thomas E
TE
Merchant
Erin N
EN
Kiehna
Chenghong
C
Li
Hemant
H
Shukla
Saikat
S
Sengupta
Xiaoping
X
Xiong
Amar
A
Gajjar
Raymond K
RK
Mulhern
D016543:Central Nervous System Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D003072:Cognition Disorders / Q000209:etiology*; D016371:Cranial Irradiation / Q000379:methods; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007360:Intelligence / Q000528:radiation effects*; D007361:Intelligence Tests; D008297:Male; D008527:Medulloblastoma / Q000188:drug therapy / Q000532:radiotherapy; D008960:Models, Psychological; D009373:Neoplasms, Germ Cell and Embryonal / Q000188:drug therapy / Q000532:radiotherapy*; D017599:Neuroectodermal Tumors / Q000188:drug therapy / Q000532:radiotherapy; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D018335:Rhabdoid Tumor / Q000188:drug therapy / Q000532:radiotherapy; D015173:Supratentorial Neoplasms / Q000188:drug therapy / Q000532:radiotherapy; D013702:Temporal Lobe / Q000528:radiation effects