Neuroimaging studies suggest that white matter and cognitive function changes were affected by breast cancer and its treatments. Our study interested in the early effect of the brain by chemotherapy. This study included 19 breast cancer survivors who had completed their chemotherapy and 20 healthy control group. Generalized q-sampling imaging (GQI) with voxel-based analysis was performed to show the brain structural differences between two groups. Multiple regression was also used to detect the correlation between Mini-Mental State Examination (MMSE) and the indices of GQI. Our results provided further evidence that breast cancer and adjuvant chemotherapy are associated with adverse effects on white matter.
METHODS
This study included 19 women with a history of breast cancer who had completed their primary chemotherapy less than 6 months before the study entry and were currently without evidence of active cancer. The chemotherapeutic drugs they used are Taxotere and Epirubicin only. We have another 20 healthy women as control group. All participants underwent MRI on a 1.5T scanner (Aera, Siemens, Germany). For diffusion imaging, we performed a single shot, diffusion-weighted spin echo-planar imaging sequence with parameters: repetition time (TR) = 7200 msec, echo time (TE) = 107 msec, resolution = 2 x 2 x 4 mm3, b-values = 0, 1000, 2000 sec/mm2 in 129 noncollinear directions, number of excitations (NEX) = 1, and acquisition time was 16 min. All participants were evaluated by the Mini-Mental State Examination (MMSE), which tests five cognitive functions, including orientation, registration, attention and calculation, recall, and language. Diffusion imaging was first corrected for eddy current by FSL. Probability distribution function was reconstructed using GQI with DSI studio. Independent t-test was performed with SPM to find the differences between two groups. Because a significant difference in age between two groups (p < 0.001) was found, we used age as covariates of no interest. Finally, multiple regression was used to detect the correlation between MMSE and the indices of GQI for all participants. GQI is a q-space reconstruction method that can reconstruct orientation distribution functions (ODF) from a variety of diffusion datasets. The GQI indices included generalized fractional anisotropy (GFA) and normalized quantitative anisotropy (NQA). GFA is defined as the standard deviation divided by the root mean square of the ODF, indicating a measurement of the anisotropy. NQA is defined as the normalized amount of anisotropic spins that diffuse along the fiber orientation3. The MMSE is a brief, quantitative measure of cognitive status in adults. It can be used to estimate the severity of cognitive impairment at a given point in time, and to document an individual's response to treatment4. The higher the MMSE score, the better cognitive performance.CONCLUSION
This study showed the decline of cerebral white matter and cognitive performance beyond chemotherapy. Our results provided further evidence that breast cancer and adjuvant chemotherapy are associated with adverse effects on white matter. Further research of this topic required larger samples and nonchemotherapy-exposed patients to determine the impact of brain organization.1. Hampson JP, Zick SM, Khabir T, et al. Altered resting brain connectivity in persistent cancer related fatigue. NeuroImage Clin. 2015; 8: 305–313.
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