Age-Specific Nonpersistence of Endocrine Therapy in Postmenopausal Patients Diagnosed with Hormone Receptor–Positive Breast Cancer: A TEAM Study Analysis

Abstract

Abstract Background. Early discontinuation of adjuvant endocrine therapy may affect the outcome of treatment in breast cancer patients. The aim of this study was to assess age-specific persistence and age-specific survival outcome based on persistence status. Methods. Patients enrolled in the Tamoxifen Exemestane Adjuvant Multinational trial were included. Nonpersistence was defined as discontinuing the assigned endocrine treatment within 1 year of follow-up because of adverse events, intercurrent illness, patient refusal, or other reasons. Endpoints were the breast cancer–specific and overall survival times. Analyses were stratified by age at diagnosis (<65 years, 65–74 years, ≥75 years). Results. Overall, 3,142 postmenopausal breast cancer patients were included: 1,682 were aged <65 years, 951 were aged 65–74 years, and 509 were aged ≥75 years. Older age was associated with a higher proportion of nonpersistence within 1 year of follow-up. In patients aged <65 years, nonpersistent patients had lower breast cancer–specific and overall survival probabilities. In patients aged 65–74 years and patients aged ≥75 years, the survival times of persistent and nonpersistent patients were similar. Conclusion. Nonpersistence within 1 year of follow-up was associated with lower breast cancer–specific and overall survival probabilities in patients aged <65 years, but it was not associated with survival outcomes in patients aged 65–74 years or in patients aged ≥75 years. These results suggest that extrapolation of outcomes from a young to an elderly breast cancer population may be insufficient and urge age-specific breast cancer studies.