http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20080421/chemo_brain_080421/
20080421?hub=Health

More about chemo brain [excerpts]
Updated Mon. Apr. 21 2008 8:28 PM ET
The study was conducted by researchers at the University of Rochester
Medical Centre (URMC) and Harvard Medical School and was published Monday
in the Journal of Biology.

he 5-FU chemotherapy drug treats cancer by halting cell division, and has
been used for more than 40 years. It is often given in combination with
other chemotherapy drugs, and is commonly used to treat breast, ovarian,
stomach, colon, pancreatic and other types of cancer.

In this study, the researchers found that cells in the nervous system
known as oligodendrocytes were severely damaged when exposed to levels of
5-FU common in cancer treatment.

Oligodendrocytes produce myelin, the fatty substance that coats nerve
cells, enabling signals to be sent rapidly between cells. Myelin membranes
turn over quite rapidly, but without oligodendrocytes, they break down,
disrupting transmission of the messages.

"It is clear that, in some patients, chemotherapy appears to trigger a
degenerative condition in the central nervous system," Noble added in his
statement.

"Because these treatments will clearly remain the standard of care for
many years to come, it is critical that we understand their precise impact
on the central nervous system, and then use this knowledge as the basis
for discovering means of preventing such side effects."

Researchers say that because not all cancer patients develop cognitive
problems, the next avenue of study should be why chemotherapy so
negatively affects some and not others.