Brain imaging reflects neurotoxicity in childhood cancer survivors

Loss of white matter fractional anisotropy, as measured by diffusion tensor magnetic resonance imaging (DTI), reflects treatment-related neurotoxicity in posttreatment survivors of childhood medulloblastoma or acute lymphoblastic leukemia, according to a report in the February 20th issue of the Journal of Clinical Oncology.

“DTI has wide applications in the brain and is especially advantageous for the evaluation of white matter fiber tracts and white matter disease,” Dr. Pek-Lan Khong from The University of Hong Kong, told Reuters Health. “DTI is a promising tool for the non-invasive evaluation of treatment-induced neurotoxicity in childhood cancer survivors.”Dr. Khong and colleagues investigated whether DTI-measured loss of white matter fractional anisotropy correlated with intelligent quotient (IQ) scores in 30 survivors of childhood medulloblastoma or acute lymphoblastic leukemia.Survivors of childhood medulloblastoma had the lowest full-scale IQ, verbal IQ, and verbal subtests, information and arithmetic, the authors report, followed by acute lymphoblastic leukemia survivors treated with irradiation and acute lymphoblastic leukemia survivors treated without irradiation, although the differences were not statistically significant.In a multivariate regression analysis, loss of white matter fractional anisotropy correlated significantly with full-scale IQ, verbal IQ, and performance IQ after adjusting for age at treatment, irradiation dose, and time interval from treatment. A 3.3% loss of white matter fractional anisotropy had a 100% specificity, 100% negative predictive value, and 0% negative likelihood ratio for having a full-scale IQ and performance IQ less than 85, the researchers note.”Together with high positive likelihood ratios, our results suggest that fractional anisotropy is a clinically useful indicator of cognitive outcome in this cohort of childhood cancer survivors,” the investigators write.”Apart from the assessment of neurotoxicity, this biomarker may potentially be useful in the assessment of timing and application of neurotoxic treatment and to test the effectiveness of neuroprotective drugs,” the authors conclude. “DTI can be added on as an additional imaging sequence during MR imaging of the brain and it takes only around 5 minutes of extra imaging time in the scanner,” Dr. Khong explained.”We are currently performing longitudinal studies for childhood cancer patients who will undergo whole brain irradiation as part of the treatment protocol,” Dr. Khong said. “We will add DTI to the MRI scanning protocol when these patients are scanned prior to treatment and at early time-points after treatment. We would like to determine the longitudinal pattern of fractional anisotropy changes and if these changes can predict IQ decline.”Neurotoxicity from childhood cancer treatment, resulting in cognitive impairment, will have an increased impact because of improvements in survival, Dr. Khong concluded.(Source: J Clin Oncol 2006;24:884-890: Reuters Health: Oncolink: March 2006.)