MedWire News: Tamoxifen use is associated with worse verbal memory and executive functioning after 1 year of adjuvant therapy, researchers from the Netherlands report.

The aromatase inhibitior, exemestane, on the other hand, does not appear to have a detrimental effect on cognitive functioning in postmenopausal patients with breast cancer.

Research suggests that estrogens can affect brain functioning. Therefore, “it is theoretically plausible that endocrine treatment for postmenopausal breast cancer, aiming at estrogen deprivation, also might influence brain functioning and cognition,” say Sanne Schagen (Netherlands Cancer Institute, Amsterdam) and colleagues.

To evaluate the influence of adjuvant tamoxifen and exemestane on cognitive functioning, Schagen and team performed neuropsychologic assessments at baseline and after 1 year of adjuvant endocrine treatment in 179 postmenopausal women with breast cancer who did not receive chemotherapy. They compared their results with those of 120 healthy controls.

The researchers report that, after adjustment for baseline performance, exemestane users (n=99) did not perform significantly worse than healthy controls on any cognitive domain after 1 year of treatment.

In contrast, tamoxifen users (n=80) performed significantly worse than healthy controls on verbal memory and executive functioning, and significantly worse than exemestane users on information processing speed.

No significant differences were found between the three groups for visual memory, working memory, verbal fluency, reaction speed, and motor speed.

“Our results support the results of earlier studies performed in postmenopausal patients with breast cancer, which suggested a detrimental effect of tamoxifen on cognitive functioning,” write Schagen and co-authors in the Journal of Clinical Oncology.

The researchers suggest: “The observed differences between tamoxifen and exemestane with respect to cognitive effects might imply different mechanisms of action of the drugs in the brain.”

They conclude that the results of the current study “justify continuing research into the cognitive effects of endocrine therapy and stress the need for more detailed knowledge about differential effects of these therapies on neuropsychological functioning.”

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