These results suggest that having a breast cancer diagnosis may be associated with cognitive impairment. While chemotherapy may have a negative impact on cognitive function, chemotherapy-related impairments appear to be more acute than chronic side effects of therapy. Further studies are needed to provide insight into the clinical significance and potential mechanisms of cancer and treatment-related cognitive impairments.

BACKGROUNDLittle is known about the effects of chemotherapy on cognitive function. The purposes of this metaanalysis were to estimate the effect sizes for the effect of chemotherapy on each domain of cognitive function and to differentiate effect sizes by each method of comparison of effects (i.e., normative data, control group, or baseline data).METHODSSixteen studies that evaluated cognitive function in chemotherapy patients were included in the study. DSTAT metaanalysis software was used to calculate an effect size and confidence intervals for each neuropsychologic test. Tests were assigned to a specific cognitive domain, and an average effect size was determined for each domain.RESULTSOnly one domain of cognitive function (i.e., visual memory) had significant chemotherapy‐induced impairment across all comparison types. However, when the neuropsychologic test scores of chemotherapy patients were compared with normative data, significant effect sizes were found for four domains of cognitive function (i.e., executive function, information processing speed, verbal memory, visual memory). In addition, significant, albeit small, effect sizes were found for language and verbal memory when chemotherapy patients' test scores were compared with test scores of healthy matched controls. All significant averaged effect sizes were in the negative direction, indicating that mean scores on neuropsychologic tests for patients who had received chemotherapy were on average lower than comparison scores.CONCLUSIONData from this metaanalysis supported the hypothesis that chemotherapy can have a negative impact on cognitive function. However, most deficits in this study ranged from small to moderate and were nonsignificant. Cancer 2005. © 2005 American Cancer Society.

Data from this study supported the hypothesis that chemotherapy may have a negative impact on select domains of cognitive function.

The ability to identify high-risk patients has important implications for practice in regard to informed consent, patient education about the effects of treatment, and preventive strategies.