Chemo drugs damage healthy brain cells

Dec 4 2006

According to new research chemotherapy drugs which are used to treat cancer, damage the brain.

But the good news is that the damage appears to be temporary.

In two separate studies researchers have found that chemotherapy affected healthy cells in the brain and caused short-term structural changes in the cognitive areas.

A team at the University of Rochester led by Dr. Mark Noble, found that several types of key brain cells were sensitive to the three drugs used for cancer: carmustine, cisplatin and cytosine arabinoside.

They say this could explain such side effects as seizures and memory loss caused by chemotherapy treatment.

They found drug therapy for cancer was found to trigger varied neurological side effects, including dementia.

The study shows that the average chemotherapy doses killed 40% to 80% of cancer cells but also affected 70% to 100% of human brain cells grown in the laboratory along with serious damage to brain cells in mice.

Dr. Noble says all three drugs tested as toxic, even at very low concentrations, to the types of brain cells whose role is to repair other cells in the brain.

In the second study a team of Japanese researchers used MRI to take high-resolution images and measure volumes in specific areas of the brain of breast cancer patients who received chemotherapy.

They then compared the brains of the cancer survivors one-year after surgery and three-years after surgery, with healthy subjects.

They found that at one-year, patients treated with chemotherapy had smaller volumes in cognitively sensitive areas, however, three-years later there were no differences between cancer patients and healthy controls.

The team led by Dr. Masatoshi Inagaki, of the Breast Cancer Survivors' Brain MRI Database Group in Japan, say though the study shows that the brain changes happen as a result of the chemotherapy rather than a secondary effect of the cancer, the changes to the central nervous system were not sustained for patients three years after chemotherapy and the chemotherapy appeared to have a temporary effect on brain structure.

Experts say doses of chemotherapy needed to treat cancer effectively while leaving the body's healthy cells as unharmed as possible is a fine balance, and all available cancer treatments have undergone extensive clinical trials to ensure that their benefits outweigh unwanted effects.

They say no patient should stop their treatment because of this research.

The research is published in the January 1, 2007 issue of CANCER, a peer-reviewed journal of the American Cancer Society.