Monday, October 13, 2008
Cancer Drug Causes Permanent Brain Damage
A widely used chemotherapy drug causes damage to the brain that can last for years after treatment is completed, according to a study conducted by researchers from the University of Rochester and published in the Journal of Biology.
"It is clear that, in some patients, chemotherapy appears to trigger a degenerative condition in the central nervous system," lead researcher Mark Noble said.
The findings may help explain why many chemotherapy patients complain of a condition called "chemo brain," suffering impaired concentration, memory loss, and even vision problems, dementia or seizures. According to a previous study by the same research team, more than 82 percent of breast cancer patients report at least one negative cognitive side effect from chemotherapy.
A different study found that 50 percent of breast cancer survivors still felt cognitively impaired one year after the end of chemotherapy, while another estimated that the effects last for years in 15 to 20 percent of women.
Many health professionals have dismissed these symptoms as side effects of cancer-related anxiety, depression or fatigue, saying there is no evidence for physical causes.
In the current study, researchers gave the drug 5-fluorouracil (5-FU) to mice and observed the effects on their brains. They found that 5-FU attacked cells in the brain known as oligodendrocytes, destroying them so thoroughly that even six months after the end of treatment, the mice's brains were almost devoid of the cells.
Oligodendrocytes are responsible for producing the protective myelin sheath that keeps nerve signals traveling smoothly. The degeneration of this sheath is associated with a variety of neurological conditions, including Alzheimer's disease and multiple sclerosis.