Factors influencing neurocognitive outcomes in young patients with benign and low-grade brain tumors treated with stereotactic conformal radiotherapy.
OBJECTIVE
To present the effect of radiotherapy doses to different volumes of normal structures on neurocognitive outcomes in young patients with benign and low-grade brain tumors treated prospectively with stereotactic conformal radiotherapy (SCRT).


METHODS
Twenty-eight patients (median age, 13 years) with residual/progressive brain tumors (10 craniopharyngioma, 8 cerebellar astrocytoma, 6 optic pathway glioma and 4 cerebral low-grade glioma) were treated with SCRT to a dose of 54 Gy in 30 fractions over 6 weeks. Prospective neuropsychological assessments were done at baseline before RT and at subsequent follow-up examinations. The change in intelligence quotient (IQ) scores was correlated with various factors, including dose-volume to normal structures.


RESULTS
Although the overall mean full-scale IQ (FSIQ) at baseline before RT remained unchanged at 2-year follow-up after SCRT, one third of patients did show a >10% decline in FSIQ as compared with baseline. Logistic regression analysis demonstrated that patients aged <15 years had a significantly higher chance of developing a >10% drop in FSIQ than older patients (53% vs. 10%, p = 0.03). Dosimetric comparison in patients showing a >10% decline vs. patients showing a <10% decline in IQ revealed that patients receiving >43.2 Gy to >13% of volume of the left temporal lobe were the ones to show a significant drop in FSIQ (p = 0.048). Radiotherapy doses to other normal structures, including supratentorial brain, right temporal lobe, and frontal lobes, did not reveal any significant correlation.


CONCLUSIONS
Our prospectively collected dosimetric data show younger age and radiotherapy doses to left temporal lobe to be predictors of neurocognitive decline, and may well be used as possible dose constraints for high-precision radiotherapy planning.
Jalali
Rakesh
R
Department of Radiation Oncology, Tata Memorial Centre, Mumbai, India. rjalali@tmc.gov.in
Mallick
Indranil
I
Dutta
Debnarayan
D
Goswami
Savita
S
Gupta
Tejpal
T
Munshi
Anusheel
A
Deshpande
Deepak
D
Sarin
Rajiv
R
D000293:Adolescent; D001254:Astrocytoma / Q000532:radiotherapy; D001932:Brain Neoplasms / Q000523:psychology / Q000532:radiotherapy*; D002528:Cerebellar Neoplasms / Q000523:psychology / Q000532:radiotherapy; D002648:Child; D003071:Cognition / Q000528:radiation effects; D003072:Cognition Disorders / Q000209:etiology*; D003397:Craniopharyngioma / Q000523:psychology / Q000532:radiotherapy; D005260:Female; D005910:Glioma / Q000523:psychology / Q000532:radiotherapy*; D006801:Humans; D007360:Intelligence / Q000528:radiation effects*; D008297:Male; D020339:Optic Nerve Glioma / Q000532:radiotherapy; D011446:Prospective Studies; D020266:Radiotherapy, Conformal / Q000379:methods; D055815:Young Adult