Cognitive Effects of Systemic Therapy in Patients with Breast Cancer.

Many patients with breast cancer complain about concentration and memory problems in connection with systemic therapy. A number of studies investigating the possible decrease in cognitive abilities were published in the 1980s. Numerous studies showed impaired performance of patients receiving chemotherapy. The results concerning profile, extent, and duration of cognitive impairments are, however, non-uniform. Increasing interest has been focused in the last years on effects of endocrine therapy on cognitive capacity - especially concerning the effects of the almost complete estrogen depletion caused by aromatase inhibitors. Often, the published studies did not evaluate particular effects of endocrine therapy without considering interference of cytotoxic treatment. Furthermore, the different endocrine medications (antiestrogens vs. aromatase inhibitors) were usually not regarded separately despite different mechanisms of action. Hence, the results of past investigations are also controversial. In the future, prospective trials with larger samples are necessary. Differentiation between chemotherapy and endocrine therapy is essential. Likewise, different types of endocrine therapy should be examined separately.