Common Chemotherapy Drug Linked to Memory Problems

By Kathleen Doheny
HealthDay Reporter
Tuesday, April 22, 2008; 4:00 AM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

MONDAY, April 21 (HealthDay News) -- Treatment with a single, commonly used chemotherapy drug causes lingering memory problems and other cognitive difficulties, a common and unpleasant side effect called "chemo brain," a new study has found.

Up to 50 percent of women with breast cancer reported having cognitive problems a year after chemotherapy treatment ended, according to one previous study.

Now, researchers from the University of Rochester Medical Center in New York and Harvard Medical School say they've discovered how the chemotherapy drug 5-fluorouracil -- or 5-FU -- affects the central nervous system even long after treatment ends. The hope is this discovery will lead to ways to decrease or eliminate the damage so cognitive functioning is preserved.

"What we found is the damage done short-term is much less than the damage that occurs long-term," said Mark Noble, senior author of the study published in the April 22 issue of the Journal of Biology. "After the drug is stopped, the cellular damage gets worse."

For years, experts questioned whether chemo brain was a result of chemotherapy or having cancer itself, said Noble, director of the University of Rochester Stem Cell and Regenerative Medicine Institute. "Could they be depressed? Was it really organic damage?" he said, listing some of the suggested possible causes.

"What our studies do is demonstrate [that] it is the chemo," he said. And, the damage can occur with treatment with the single drug, not only the "cocktails" of drugs often used to treat cancer.

In a previous study, Nobel and his colleagues demonstrated that three common chemotherapy drugs were more toxic to healthy brain cells than to the cancer cells they were meant to treat. These studies were among the first to establish a biological basis for chemo brain. But the research didn't explain why the cognitive ill effects persist in some patients.

For the new study, Noble and his colleagues exposed cell lines in a laboratory and in mice to doses of 5-FU, and then evaluated the drug's effects. The drug is used to treat malignancies of the breast, ovaries, stomach, colon and other sites.