 Difficulty with some mental functions after chemotherapy, often referred to by cancer survivors as "chemo brain" is real, according to a researcher who says future research should focus on learning the cause, how to prevent these difficulties and how to best help patients who confront them.
Tim A. Ahles, PhD, professor of psychiatry at Dartmouth Medical School, presented the results of his research during a panel on breast cancer Tuesday at the 42nd annual Science Writers Seminar of the American Cancer Society (ACS) in Tampa, Fla.
The difficulties with mental function reported by some cancer survivors include problems with memory and learning, attention and concentration, language and judging spaces and layout when moving about.
The negative impact that cancer treatment can have on survivors has been recognized by experts, but most of the focus in the past has been on patients who received radiation therapy to the brain, or high-dose chemotherapy with bone marrow or stem cell transplant. Many studies have looked at mental function during and shortly after treatment. Few have looked at long-term effects.
Dr. Ahles? study compared 71 patients who had standard-dose chemotherapy for breast cancer or lymphoma to 57 patients who had had only local therapy -- surgery and/or radiation without chemotherapy.
Because the study focused on long-term effects of chemotherapy, all the patients included were at least five years past their treatments. They were all cancer-free at the time of the study and had no other medical problems that could affect mental function.
The study results showed that those treated with chemotherapy scored significantly lower on standardized tests measuring mental and psychological functions than those who had only local therapy. The chemotherapy patients? scores were lower on average whether or not patients reported having depression, anxiety or fatigue, which can also reduce mental function.
This study is important because it looks at standard doses of chemotherapy, said William Wood, chair of the seminar?s breast cancer panel and chairman of surgery at Emory University in Atlanta. Previous studies have looked at high-dose chemotherapy.
Dr. Ahles said the study points to the need to learn exactly how chemotherapy causes difficulty with mental functions and which chemotherapy drugs are most likely to cause it. Researchers should also look at how people recover from these difficulties ? and why some patients don?t fully recover. "There are two theories about how this works," Dr. Ahles said. "One is that drugs may be crossing the blood-brain barrier more than we thought and having an effect. The second is an immune system type of effect. This is the kind of study that triggers more questions than it answers."
Another expert points out that not all patients will experience mental difficulties and that some who do find those difficulties are not permanent. "While this research provides valuable information about another side effect of chemotherapy, we need to remember that many cancer patients who undergo chemotherapy either experience no cognitive impairment or find that most mental difficulties, such as confusion and memory impairment, are only temporary," said Kevin Stein, PhD, a clinical health psychologist with the Behavioral Research Center of the ACS.
Future research also should focus on ways to prevent chemotherapy from harming mental function, and the best ways for patients already affected to minimize the impact of those effects in their daily lives, says Dr. Ahles.
He added that the study points to the need for patients to be aware of the possibility that chemotherapy may have long-term effects on mental function, so that they can make informed decisions about which treatment options are best for them, given individual circumstances.
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