According to results from the neuropsychological side study of the Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial, the adjuvant use of tamoxifen is associated with a reduction in some aspects of cognitive functioning in postmenopausal patients with breast cancer, whereas exemestane does not seem to be associated with any reduction in function.
The TEAM trial was a randomised study comparing the efficacy and safety of five years of adjuvant exemestane (25 mg/d) with 2.5 to 3 years of tamoxifen (20 mg/d) followed by 2 to 2.5 years of exemestane. Participants had adenocarcinoma of the breast, positive oestrogen and/or progesterone receptor status, and had undergone surgery with a curative intent. This neuropsychological sub-study included 179 women who took part in the main study - 80 tamoxifen users (mean age 68.7 years; range 51 to 84) and 99 exemestane users (mean age 68.3 years; range, 50 to 82). Anyone who had received adjuvant chemotherapy or had CNS disease or signs of dementia according to a dementia screening tool were excluded from participation. A control group consisting of healthy female friends or relatives having approximately the same age as the participating TEAM patients was included (n=120, mean age 66.2 years), in order to take into account test-retest effects of neuropsychological tests.
Neuropsychological assessments were performed before the start and after 1 year of adjuvant endocrine treatment. After adjustment for baseline performance, women randomised to exemestane did not perform worse on any cognitive domain after one year. Women randomised to tamoxifen however performed worse than healthy controls on verbal memory and executive functioning, and worse than users of exemestane on information processing speed. There were no differences between the groups in terms of visual memory, working memory, verbal fluency, reaction speed, and motor speed.
The authors note that the impact (if any) of the observed effects on daily life has yet to be determined, but that their results ‘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.’