Structural brain changes found in chemoradiation-treated glioblastoma patients

By Shreeya Nanda, Senior medwireNews Reporter

US researchers find evidence of marked and progressive brain atrophy during standard chemoradiation therapy in patients with glioblastoma.

But Jorg Dietrich (Massachusetts General Hospital, Boston) and colleagues temper their conclusions by pointing out that their results do not “provide conclusive evidence regarding the irreversibility of these changes, as the longest follow-up was 35 weeks”.

They write in Neurology: “While we did not find evidence of reversibility within this time period, we cannot exclude the possibility that some degree of [central nervous system] repair leads to partial or complete reversal of morphometric changes in long-term survivors.”

The study included 14 glioblastoma patients treated with 6 weeks of temozolomide plus focal radiotherapy followed by up to 6 months of temozolomide alone. Study participants underwent scanning 3 to 7 days and 1 day prior to initiating treatment, followed by weekly and monthly scans during the chemoradiation and chemotherapy alone phases, respectively.

Voxel-based morphometry revealed a significant reduction, independent of age, gender and tumour volume, in whole brain and cortical grey matter volumes from baseline to final follow-up (average percent volume reductions at 35 weeks of between 1.5% and 2.0% and between 4.0% and 5.0%, respectively). But there were no significant changes in white matter volumes.

Noting that the latter finding differs from previous reports, Dietrich et al wonder whether focal rather than whole-brain radiotherapy may spare parenchymal white matter from atrophy.

Volumetric analysis showed that anterior lateral ventricle volume increased significantly over time, independent of confounders such as age, gender and steroid use during chemoradiation. By contrast, hippocampal volumes did not show any significant longitudinal changes.

Moreover, there was a significant confounder-independent increase in the apparent diffusion coefficient within the subventricular zone.

“The use of neuroimaging at multiple time points over several months offers a novel view of the nature, severity, and time course of treatment-associated brain changes in patients with glioma”, say the researchers.

But they add: “Definitive confirmation and validation of our findings must await further exploration in larger datasets.”

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