Patterns of change in cognitive function with anastrozole therapy.

BACKGROUND The purpose of this study was to examine and compare the effects of the first 18 months of anastrozole therapy on cognitive function in women with breast cancer. METHODS This large, longitudinal cohort study was composed of postmenopausal women with early-stage breast cancer who received chemotherapy plus anastrozole (n = 114) or anastrozole alone (n = 173) and a control group (n = 110). Cognitive function was assessed before systemic therapy and 6, 12, and 18 months after therapy initiation and at comparable time points in controls. RESULTS The chemotherapy-anastrozole and anastrozole-alone groups had poorer executive function than the controls at nearly all time points (P < .0001 to P = .09). A pattern of deterioration in working memory and concentration was observed during the first 6 months of anastrozole therapy for the chemotherapy-anastrozole group (P < .0001 and P < .0009, respectively) and the anastrozole-alone group (P = .0008 and P = .0002, respectively). This was followed by improved working memory and concentration from 6 to 12 months in both groups. The anastrozole-alone group had a second decline in working memory and concentration from 12 to 18 months after the initiation of therapy (P < .0001 and P = .02, respectively). CONCLUSIONS Women with breast cancer had poorer executive functioning from the period before therapy through the entire first 18 months of therapy. A pattern of decline in working memory and concentration with initial exposure to anastrozole was observed. Women receiving anastrozole alone had a second deterioration in working memory and concentration from 12 to 18 months after therapy initiation. The longer term effects (>18 months) of anastrozole on cognitive function remain to be determined. Cancer 2015;121:2627–2636. © 2015 American Cancer Society.