Breast Cancer: Does Tamoxifen Affect Cognitive Function in Postmenopausal Women?

Florien Boel MSc VU University Medical Center Department of Medical Psychology Amsterdam, The Netherlands Interview with:
Florien Boel MSc
VU University Medical Center
Department of Medical Psychology
Amsterdam, The Netherlands

Medical Research: What are the main findings of the study?

Answer: In postmenopausal breast cancer patients, endocrine therapy is widely used, and often for many years on end. Endocrine therapy is thought to have an effect on cognitive functioning, but previous studies have not yet accounted for the possible influence of the diagnosis of cancer and subsequent anxiety, depression or fatigue on cognitive performance. In addition, the cognitive effects of endocrine therapy after long-term use are still mostly unknown.

Therefore, we compared cognitive functioning of postmenopausal breast cancer patients who underwent surgery and/or radiotherapy (N=43) with the cognitive performance of women who also received adjuvant endocrine therapy (tamoxifen) (N=20) and a group of healthy matched individuals (N=44). In accordance with the literature, we found that especially cognitive domains that rely heavily on verbal abilities (verbal memory and fluency) seem to be at risk for deterioration during long-term treatment (~2.5 years) with tamoxifen.

Medical Research: Were any of the findings unexpected?

Answer: Yes, we found that participants in the adjuvant tamoxifen group had worse fluency scores than healthy controls, but not when compared with the surgery and/or radiotherapy group. We had expected that the adjuvant group would also perform worse than this cancer control group. Perhaps future studies, preferably including larger sample sizes, may be able to investigate this further.

Medical Research: What should readers take away from your report?

Answer: With this study, we aimed to provide additional insight into the potential long-term effects of different breast cancer treatments on cognitive functioning. As we included a group of patients who only underwent surgery and/or radiotherapy and a group of healthy controls, we could account for the mental and physical influences of the diagnosis and treatment of while examining cognitive performance. While cognitive domains relying on verbal abilities, e.g., verbal memory and fluency, seem to be at particular risk for deterioration during treatment with tamoxifen, further preclinical and clinical research is needed to guide the development of intervention strategies aimed to prevent or diminish cognitive symptoms.

Medical Research: What recommendations do you have for future research as a result of this study?

Answer: Basic research into the mechanisms underlying the long-term cognitive effects of endocrine treatments and imaging studies on the neural substrate of observed cognitive problems are needed. In addition, to gain further knowledge on the long-term cognitive effects of endocrine treatments and the causal relationships between cognitive sequelae of endocrine treatments, we highly recommend that future studies incorporate a longitudinal study design.


Cognitive functioning during long-term tamoxifen treatment in postmenopausal women with breast cancer.
Boele FW1, Schilder CM, de Roode ML, Deijen JB, Schagen SB.

Menopause. 2014 Jun 23. [Epub ahead of print]


Last Updated on July 17, 2014 by Marie Benz MD FAAD