Cognitive effects of adjuvant endocrine therapy in older women treated for early-stage breast cancer: a 1-year longitudinal study

Purpose Evidence suggests endocrine therapy (ET) for breast cancer (BC) has adverse cognitive effects, but its specific effects on older women are unknown. This is despite the fact that older women are at increased risk of both breast cancer (BC) and cognitive decline relative to younger women. This study prospectively examined the cognitive effects of ET in a cohort of older BC patients. Our primary outcome measure was change in verbal memory, the cognitive domain most consistently affected by estrogen deprivation. Methods Forty-two chemotherapy-naïve women age 60+, without dementia and recently diagnosed with hormone receptor-positive BC, completed neuropsychological tests at the time of ET initiation and after 1 year of treatment. Change in age-standardized verbal memory performance was examined using paired t tests. To assess a broader range of potential cognitive effects, we also examined changes in visual memory, processing speed, frontal executive function, and perceptual reasoning. Results Participants exhibited significant decline from baseline to 1 year in verbal memory ( p = 0.01). This decline was small to moderate in effect size ( d = − 0.40). Performance on other domains did not change significantly over the year (all p > 0.05). Conclusions Our findings suggest potentially detrimental effects of ET on verbal memory in older women after just 1 year of treatment. Given that ET is prescribed for courses of 5 to 10 years, additional studies examining longer-term effects of treatment in older women are critical.