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According to an early online publication in the journal Cancer, adjuvant chemotherapy (chemotherapy administered following surgery) appears to temporarily change the size of some parts of the brain in patients with breast cancer. These findings, if confirmed, may help explain the phenomenon known as “chemo brain”.

A large portion of patients with early breast cancer will ultimately receive adjuvant chemotherapy. Patients undergoing chemotherapy have long complained of a phenomenon referred to as chemo brain. Chemo brain refers to changes in cognitive function, such as loss of memory and inability to think clearly or perform some daily functions. Researchers have not been able to pinpoint the cause of chemo brain, but current studies are evaluating brain structure and function in order to better understand the effects of chemotherapy on the brain.

Researchers from Japan recently conducted a study to evaluate data from patients with breast cancer who had received adjuvant chemotherapy; data from these patients was compared to data from patients with breast cancer who had not received chemotherapy and to healthy individuals. The researchers compared magnetic resonance imaging (MRI) scans, which measured volumes of specific regions of the brain. Scans were taken from patients at one year of their surgery and at three years following surgery.

  • Among patients who were within one year of surgery, those who received chemotherapy had significantly smaller volumes of specific parts of the brain involved in memory and cognition (prefrontal, parahippocampal, cingulated gyrus, and precuneus regions) than patients who had not received chemotherapy.
  • Among patients who were three years from therapy, there were no significant differences in brain volumes between those who had received chemotherapy and those who had not received chemotherapy.
  • Overall, cancer survivors (including those who did and did not receive chemotherapy) did not show a significant difference in brain volumes when compared to healthy individuals, indicating that the cancer process itself was not responsible for the changes in brain volume.
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The researchers concluded that treatment with adjuvant chemotherapy among breast cancer patients is associated with a temporary decrease in brain volume in some areas of the brain that are involved in memory and cognition. These changes in brain volume may be associated with the development of chemo brain. Additional studies are evaluating this issue.

Reference: Inagaki M, Yoshikawa E, Matsuoka Y, et al. Smaller Regional Volumes of Brain Gray and White Matter Demonstrated in Breast Cancer Survivors Exposed to Adjuvant Chemotherapy. Cancer [early online publication]. November 27, 2006. DOI: 10.1002/cncr.22368.

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