Study: Chemotherapy Can Alter Brain by Killing Cells
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Temporary Brain Shrinkage May Explain ‘Chemobrain’
Neil Osterweil, Senior Associate Editor, MedPage Today
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
November 27, 2006
CHIBA, Japan, Nov. 27 — The thought-fogging phenomenon known as “chemobrain” appears to be related to a reversible shrinking of brain structures induced by chemotherapy, researchers here have found.
scans of breast cancer survivors within a year of completing adjuvant
chemotherapy showed significantly smaller regional volumes of gray and
white matter in areas involved in cognitive function compared with other
survivors or healthy controls, they reported in an online release from
the Jan. 1 issue of Cancer.
three years after treatment, however, those differences had vanished,
said Masatoshi Inagaki, M.D., Ph.D., of the National Cancer Center
Hospital East, and colleagues.
lead to the idea that adjuvant chemotherapy could have a temporary
effect on brain structure,” the authors wrote. “These findings
can provide new insights for future research to improve the quality of
life of cancer patients who receive adjuvant chemotherapy.”
undergoing chemotherapy often complain of cognitive and memory problems,
and clinical studies have confirmed cognitive declines. Evidence from
animal studies has also shown that systemic chemotherapy can have
agents are hypothesized to have neurotoxic potential through their
ability to interfere with DNA and RNA synthesis and function, inhibition
of microtubule formation, and/or immunosuppressive properties,” the
They performed a retrospective study to determine whether there were significant regional brain-volume differences between breast cancer survivors exposed to adjuvant chemotherapy and those who did not undergo chemotherapy.
authors compared gray and white matter volumes as measured on
high-resolution 1.5-tesla brain MRI scans from databases of breast
cancer survivors, both in breast cancer patients who were within one
year of their surgery, and those who were three years out from surgery.
They also compared data on cancer survivors with scans taken from
healthy controls recruited from the local population for the study.
found that in the one-year study survivors who underwent chemotherapy
had smaller gray matter and white matter in areas involving cognition
and memory, including the prefrontal, parahippocampal, and cingulate
gyrus, and precuneus regions, compared with patients who were not
exposed to chemotherapy.
they looked at the three-year data, however, they saw no differences
between the patients who had received adjuvant chemotherapy and those
who had not.
authors also performed an analysis to determine whether the volume of
key brain structures correlated with scores on the Weschler Memory
Scale-Revised, and found that the volumes of the prefrontal,
parahippocampal gyrus, and precuneus regions were significantly
correlated with indices of attention and concentration and/or visual
they compared the brain regions of all cancer survivors at the one- and
three-year intervals with those of healthy controls, however, they did
not see any significant differences, suggesting that there were no
significant effects of the cancer itself on cognitive function.
authors noted that the effects of chemotherapy on specific brain regions
were unclear, and that the potential pathophysiologic mechanisms for the
differences they saw in regional brain volumes were unknown.
also noted that “the reason we did not explore effects of each
chemotherapeutic agent in the study setting was that interactions
between each chemotherapeutic agent may exist and may make our inference
also pointed out that the current study did not have any specific
functional targets related to each of the detected regions.