Chemotherapy and Long-Term Memory

A study just published by a team of Dartmouth researchers in the Journal of Clinical Oncology found that breast cancer and lymphoma patients who had undergone chemotherapy treatment for their disease may experience a subtle loss of memory as long as ten years after their treatment has ended.

An earlier study published a Canadian team of researchers in the same journal found that chemotherapy can have an impact on memory and mental sharpness during the course of treatment.

The Dartmouth-led study, headed by Dr. Tim Ahles, evaluated 35 breast cancer patients and 36 lymphoma patients who were treated with systemic chemotherapy an average of ten years earlier. They compared the patients' results on a series of cognitive function tests with a similar number of breast cancer and lymphoma patients who were treated ten years ago with local therapy (surgery or radiation) but not chemotherapy.

They found that the systemic chemotherapy patients scored significantly lower on tests of verbal memory, working memory, and psychomotor functioning. Furthermore, the researchers noticed a strong correlation between the number of cycles of chemotherapy received and the patients' eventual neuropsychological scores.

Ahles speculated that their findings may indicate that memory loss could result from chemotherapeutic agents crossing the blood-brain barrier, or possibly result from certain metabolites in the drugs. However, he said that further research is clearly needed to explore the relationship between chemotherapy and long-term memory loss, if any does indeed exist.

An earlier study published in the Journal of Clinical Oncology found that chemotherapy can have an immediate impact on memory and mental sharpness during the course of treatment, and possibly thereafter. But the researchers, led by Dr. Ian Tannock of Princess Margaret Hospital in Toronto, said the impact appeared to be temporary and was usually subtle.

Tannock's team assessed the memory and language skills of 31 women over the course of their chemotherapy treatment. They also tested cognitive function in 40 women who had completed chemotherapy at least one year earlier. They found that many of the women showed a small loss of mental sharpness. They speculated that the chemotherapy drugs may have some impact on healthy brain cells in the same way these drugs also impact other healthy cells to cause side effects such as hair loss and nausea.

Both Ahles and Tannock strongly cautioned that their results are preliminary and should in no way discourage cancer patients from chemotherapy treatment for their disease.

SOURCES:
Journal of Clinical Oncology, January 2002; 20:485-493
Journal of Clinical Oncology, July 2000; 18:2695-2701

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