The cognitive effects of endocrine therapy in survivors of breast cancer: A prospective longitudinal study up to 6 years after treatment

Background: After treatment of primary breast cancer, endocrine therapy (ET) is prescribed for patients with hormone receptor-positive cancers. Despite ET recommendations of 5 to 10 years of treatment, to the authors' knowledge there is little prospective study of its impact on cognitive function over an extended period of time. ET has known pharmacologic effects on the brain. Cognitive side effects are a concern for many women, with mixed findings reported in various studies. The current prospective longitudinal study examined the neuropsychological effects of ET over time, up to 6 years after treatment.

Methods: A total of 189 survivors of early-stage breast cancer enrolled in the study prior to initiating ET if prescribed, and were followed at 6 months (175 patients), 12 months (173 patients), and for 3 to 6 years (102 patients) with self-report and neuropsychological assessments. Using linear mixed models, the authors examined whether neuropsychological performance or impairment rates differed over time based on whether or not ET was received.

Results: The authors did not find any effect of ET on neuropsychological performance or impairment at any time point among survivors who received it compared with women who did not. However, those who participated in the 3-year to 6-year year visit demonstrated better executive function at baseline.

Conclusions: In the current observational cohort study, no detrimental effect of ET on cognitive function was identified in survivors of early-stage breast cancer receiving treatment with ET compared with those who were not.