Images confirm what patients know: Chemo can hurt the brain

For the first time, scientists have used brain imaging to visualize how cancer drugs can affect breast cancer survivors years after treatment. These findings help pinpoint what happens in patients who complain of ``chemo brain" -- chronic difficulties with concentration, multitasking, and particularly short-term memory.

Researchers at the University of California, Los Angeles, took PET scans of the brains of 34 women as they performed short-term memory tests. Those who had received chemotherapy five to 10 years earlier required significantly more blood flow in a brain region associated with short-term memory than healthy women or those who only had surgery to treat the cancer.

Their brains were clearly working harder to perform the same tasks, said the lead author, Dr. Daniel Silverman. For these women, brain cells in that memory region also showed lower basic levels of activity when they were at rest, meaning they have reduced capacity to communicate with other nerve cells.

The brain scans of women who also took tamoxifen, often prescribed to prevent breast cancer recurrences, showed less at-rest activity than in women who had chemotherapy alone.

``The good news is that breast cancer patients are surviving longer," Robert Raffa, a Temple University pharmacology professor who is unconnected to the research, wrote in an e-mail. ``The bad news is that the longer survival is uncovering adverse effects of these treatments that can last, as this study shows, for years afterward."

Timothy Ahles, director of the Neurocognitive Research Laboratory at Memorial Sloan Kettering Cancer Center in New York, said more research is needed to understand the link between medications and ``brain fog," and the work is too new to use as the basis for treatment decisions.

Still, he said, the findings validate the frustrations of breast cancer survivors, many of whom report subtle but lifestyle-changing difficulties in completing mental tasks. It's not clear whether chemotherapy treatments for other diseases cause similar effects.

Silverman and his colleagues are starting a federally funded study that will track women receiving chemotherapy and associated treatments over five years, monitoring factors such as brain activity and hormone levels.

Because brain chemical changes precede actual symptoms by several years, Silverman said, he is optimistic that doctors will someday be able to use PET scans to identify patients who are susceptible to brain changes and prevent the damage.

No therapy is currently proven to prevent or treat chemo brain, though ongoing clinical studies are testing ginkgo biloba and Alzheimer's therapies as potential remedies, according to Dr. Janette Vardy, an oncologist at Princess Margaret Hospital in Toronto.