Breast cancer chemotherapy affects gray matter
MedWire News: US researchers have used magnetic resonance imaging (MRI) to show that chemotherapy is associated with reduced brain gray matter density in breast cancer patients, which partially recovers over time.
Gray matter changes were most prominent in frontal, temporal, and cerebellar regions, consistent with the profile of cognitive dysfunction observed in breast cancer patients after chemotherapy, Andrew Saykin (Indiana University School of Medicine, Indianapolis) and colleagues report.
To investigate the neural mechanisms underlying cognitive changes related to breast cancer and its treatment, Saykin and team carried out a prospective MRI study of women undergoing treatment with or without chemotherapy (n=17 and 12, respectively), as well as healthy controls (n=18).
They underwent MRI scans at baseline (after surgery but before radiation, chemotherapy, and/or anti-estrogen treatment), 1 month after completion of chemotherapy (M1), and 1 year later (Y1).
The researchers report that there were no between-group gray matter differences at baseline, as assessed by voxel-based morphometry.
However, group-by-time interaction analyses revealed reduced gray matter density from baseline to M1 in both cancer groups compared with controls.
Patients who received chemotherapy had decreased gray matter density in the bilateral frontal, temporal, and cerebellar regions and the right thalamus at M1, compared with baseline.
At Y1, some of these regions, including the bilateral superior frontal, left middle frontal, and right superior temporal and cerebellar regions had recovered, but reduced density persisted in other regions.
Of note, no significant within-group changes in gray matter density from baseline to M1 or Y1 were observed among the patients who did not receive chemotherapy or the controls.
This suggests that the gray matter alterations observed are related to the effects of chemotherapy, rather than solely reflecting host factors, the cancer disease process, or effects of other cancer treatments, remark Saykin et al in the journal Breast Cancer Research and Treatment.
Indeed, analysis of potential confounders revealed that the researchers' findings were not attributable to recency of cancer surgery, disease stage, psychiatric symptoms, psychotropic medication use, or hormonal treatment status.
"These analyses, suggest an anatomic basis for the cognitive complaints and performance changes seen in patients [with breast cancer]," said Saykin.
He added: "Memory and executive functions like multi-tasking and processing speed are the most typically affected functions and these are handled by the brain regions where we detected gray matter changes."
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By Laura Dean