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Adapted from the NCI Cancer Bulletin, vol. 3/no. 47, Dec. 5, 2006 (see the current issue ²).

The cognitive impairments demonstrated by breast cancer patients who undergo chemotherapy - symptoms commonly called "chemobrain" - may be related to structural brain changes, according to Japanese researchers in a study published early online November 27, 2006, in the journal Cancer (see the journal abstract).

The researchers used high-resolution brain magnetic resonance imaging to look at the distribution of gray and white brain matter regions in women who received chemotherapy after surgery and women who did not receive chemotherapy, with a set of healthy controls for comparison.

Fifty-one women who received chemotherapy were scanned in the first year after surgery, and 73 women were scanned three years after their surgery; 55 women who didn't receive chemotherapy were scanned in the first year after surgery, and 59 were scanned three years after surgery. The women received Wechsler Memory Scale-Revised testing for cognitive indices including attention, concentration, and visual memory.

The researchers found that in the first year of chemotherapy treatment, women had smaller right-prefrontal brain regions and smaller parahippocampal gyri (regions that are associated with memory) than women who didn't receive chemotherapy, and these changes correlated with decreased cognitive function. Other areas with similar shrinkage, also associated with memory, included the superior and middle-frontal gyri, the cingulated gyrus, and the precuneus.

By contrast, these structural differences were not seen in the group that was analyzed three years after surgery and chemotherapy, leading the authors to suggest "that the brain volume change related to adjuvant chemotherapy may well recover over the course of time." They noted that while other studies have shown cognitive effects lasting longer than three years, these studies have also demonstrated eventual cognitive recovery.

Glossary Terms

Additional cancer treatment given after the primary treatment to lower the risk that the cancer will come back. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, targeted therapy, or biological therapy.

A procedure in which radio waves and a powerful magnet linked to a computer is used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. Magnetic resonance imaging makes better images of organs and soft tissue than other scanning techniques, such as computed tomography (CT) or x-ray. Magnetic resonance imaging is especially useful for imaging the brain, the spine, the soft tissue of joints, and the inside of bones. Also called MRI, NMRI, and nuclear magnetic resonance imaging.