The impact of adjuvant therapy for breast cancer on cognitive function: current evidence and directions for research.

Available evidence supports the hypothesis that adjuvant chemotherapy for breast cancer can produce cognitive deficits, and that these deficits may have a significant impact on patients' quality of life. Studies have generally compared the results of a variety of cognitive measures performed following treatment to standardized population-based norms or to cancer patients who received local therapy, rather than to the individual's baseline level of functioning. Several longitudinal studies are in progress or in the planning stages to better quantify and understand the incidence and impact of cognitive effects of adjuvant chemotherapy, and to identify possible susceptibility factors in subgroups. Although the neurocognitive changes appear to be subtle, there may be enough data to consider discussing the possibility of cognitive dysfunction as an adverse effect when assessing the risks and benefits of adjuvant chemotherapy. Likewise, as the aromatase inhibitors are increasingly given to larger numbers of women in the adjuvant setting, it will be important to understand the cognitive impact of estrogen deprivation. Finally, there is interest in examining supportive pharmacologic or behavioral measures that might prevent or decrease cognitive effects in this setting. Herein, the data on cognitive changes associated with chemotherapy for breast cancer, current and future research directions, as well as possible treatments are reviewed.