Cognitive problems after chemotherapy for breast cancer

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cancer treatment

Most women facing chemotherapy for breast cancer know about its side effects. They've heard about them from friends or family, or their physicians have explained the unpleasant possibilities: hair loss, nausea, fatigue, mouth sores, diarrhea, and emotional distress.

Fortunately, new medications and treatments can help ease some of chemotherapy's worst discomforts. But one reported side effect goes largely unmentioned --and unaddressed. It's cognitive dysfunction, known in this context as "chemo brain." Patients have reportedly complained about chemo brain for a long time now, but few doctors are familiar with it. And researchers have only recently turned their attention to learning what's behind it.

Chemo brain is not a scientifically defined syndrome, but a small body of research suggests that 20%-30% of chemotherapy recipients may suffer from it and that it may last as long as 10 years. However, there's no evidence that it causes permanent damage.

What are the symptoms?
A woman who reports chemo brain generally describes it as an increase in distractibility and inattentiveness. She may forget where she parked the car, have trouble concentrating on an in-depth article or book, or ask a question that was answered only moments before. She may also have trouble finding the right words to describe things.

These difficulties may sound familiar to women so busy juggling job challenges, children, aging parents, and physical changes that they can't keep track of all of life's details. Also, we should expect some age-related changes in memory. What seems to distinguish the effects of chemotherapy is the sudden increase in problems with memory and thinking.

Why does it happen?
At this point, experts have only theories to explain this phenomenon. Some believe that the sudden early menopause induced by chemotherapy may dramatically affect cognitive function, albeit in the short term.

Other specialists think that what alters cognitive function is the combination of the many different drugs that women take during and after chemotherapy, including steroids and antihistamines--much the same way that multiple medications can affect older people. Another possibility is that chemotherapy drugs, especially at high doses, may somehow damage the brain.

Breast cancer survivors seem to report chemo brain more often than people treated for other cancers. It's possible that their physiological situation is unique. But they also tend to be well connected through support groups and Internet activities. They may have been the first to recognize and openly discuss a pattern of cognitive problems.

Growing research interest
One central issue is whether the symptoms are caused by chemotherapy or by the stress and depression that accompany a cancer diagnosis. The little research that has been done suggests that chemotherapy is the major culprit.

A Dutch study compared breast cancer patients treated with chemotherapy to those who had only surgery and radiation (Journal of the National Cancer Institute, Feb. 4, 1998). Two years after treatment, patients who had received chemotherapy continued to have reduced cognitive ability compared to those who'd had other forms of treatment.

Moreover, in that study, the risk for cognitive impairment correlated with the amount of chemotherapy taken. High-dose chemotherapy patients had a risk for cognitive problems 3.5 times that of women receiving standard-dose therapy and 8 times that of women who had no chemotherapy.

A more recent study carried out at the Dartmouth-Hitchcock Medical Center reported similar results over a longer period of time (Journal of Clinical Oncology, Jan. 15, 2002). Researchers compared 71 breast cancer and lymphoma patients who had received chemotherapy to 57 cancer patients who had not. All of the women were at least five years past diagnosis, disease-free, and no longer receiving cancer treatments.

As in the Danish study, the Dartmouth research found that chemotherapy patients performed worse on cognitive tests than women who were treated with radiation and surgery. Levels of depression, anxiety, and fatigue were similar in the two groups, suggesting that such factors were not responsible for the cognitive differences.

The search for more evidence
While most published studies document a link between cognitive dysfunction and chemotherapy in breast cancer patients, none of them have tested women before treatment. Therefore it's hard to know the extent of cognitive change following chemotherapy. Also, no research has studied whether tamoxifen, a hormonal therapy, influences cognitive function. (Some research suggests that tamoxifen helps preserve it.)

One research project designed to correct this shortcoming is under way at the Vermont Cancer Center. Researchers there are measuring the patients' cognitive abilities before they undergo chemotherapy, with or without tamoxifen, and then again after. Results should be out some time this year.

Possible treatments
Because so little is known about chemo brain, clinicians are hard-pressed for ideas about how to treat it.

A small study presented at the May 2002 annual meeting of the American Society of Clinical Oncology suggests that weekly shots of epoetin alpha may improve cognitive function in patients undergoing chemotherapy. Epoetin alpha is a synthetic version of erythropoietin, a hormone that stimulates red blood cell production. Another, larger trial will follow up on these results.

A different study will test the stimulant methylphenidate (Ritalin) as a treatment for both fatigue and chemotherapy-associated cognitive dysfunction in breast cancer patients.

What to do

We don't know whether any medications can help with chemotherapy-related cognitive problems. Trials are under way to find out. In the meantime, you can adopt some tried-and-true strategies that others have used to cope with memory difficulties.

• Make lists, lists, and more lists. Write down everything, even where you park your car.

• Try focusing strategies. If you're having trouble in one area, such as misplacing your keys, take extra time to think about or visualize what you're doing every time you put them down.

• Tell your friends and family what you're going through so that they'll understand when you forget things you normally wouldn't.

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