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.