Smaller regional volumes of brain gray and white matter demonstrated in breast cancer survivors exposed to adjuvant chemotherapy

BACKGROUND: Previous studies have shown cognitive impairment in breast cancer survivors who were exposed to adjuvant chemotherapy. Neural damage by chemotherapy might have played some part in these findings. The current study explored the regional brain volume difference between breast cancer survivors exposed to adjuvant chemotherapy (C+) and those unexposed (C-). METHODS: High-resolution 1.5-tesla brain magnetic resonance imaging (MRI) databases of breast cancer survivors and healthy controls were used. Brain images were preprocessed for optimal voxel-based morphometry. Comparisons of gray matter and white matter were performed between the C+ and the C- groups, by using MRI scans from within 1 year (the 1-year study, n = 51 and n = 55, respectively) or 3 years after their cancer surgery (the 3-year study, n = 73 and n = 59, respectively). As exploratory analyses, correlation analyses were performed between indices of the Wechsler Memory Scale-Revised and regional brain volume where the volume were significantly smaller. As a reference, MRI scans of cancer survivors were compared with those of healthy controls (n = 55 for the 1-year study and n = 37 for the 3-year study). RESULTS: The C+ patients had smaller gray matter and white matter including prefrontal, parahippocampal, and cingulate gyrus, and precuneus in the 1-year study. However, no difference was observed in the 3-year study. The volumes of the prefrontal, parahippocampal gyrus, and precuneus were significantly correlated with indices of attention/concentration and/or visual memory. Comparisons with healthy controls did not show any significant differences. CONCLUSIONS: Adjuvant chemotherapy might have an influence on brain structure, which may account for previously observed cognitive impairments.