Cognitive function after adjuvant treatment for early breast cancer: a population-based longitudinal study.

The purpose of this study was to examine cognitive function in patients with early breast cancer before and after adjuvant chemotherapy or 6 months of tamoxifen. We performed a population-based study in the county of North Jutland, Denmark, including 120 women aged <60 years who received adjuvant chemotherapy with seven cycles of cyclophosphamide, epirubicin and fluoruracil or adjuvant tamoxifen for 6 months for early breast cancer from 2004 to 2006. They were compared with an aged-matched group of 208 women without previous cancer selected randomly from the same population. Data were collected before start of adjuvant treatment and after 6 months by neuropsychological tests and questionnaires to evaluate cognitive function, quality of life and psychological distress. Neuropsychological tests did not reveal any differences in cognitive function between breast cancer patients after chemotherapy and healthy controls. Patients rated their own cognitive functions as improved after 6 months, and patients, who did not receive adjuvant medical treatment, reached the same level as controls within 6 months. Patients receiving chemotherapy or tamoxifen were up to three times more likely than controls to rate themselves as impaired at 6 months. Our results do not support that adjuvant chemotherapy is associated with cognitive side effects in breast cancer patients.