Identifying adherence barriers to oral endocrine therapy among breast cancer survivors

Approximately 70-80% of breast cancers are hormone receptor-positive (HR+). OET, including tamoxifen and aromatase inhibitors, is considered standard adjuvant therapy for HR+ breast cancer. Despite demonstrated benefits, nearly half of patients are non-adherent and over two-thirds discontinue therapy before the recommended 5 years. Our objective was to identify and summarize literature-reported barriers associated with non-adherence/non-persistence to OET among breast cancer survivors.

A PUBMED literature search was conducted using the following terms: 'breast cancer,' 'oral endocrine therapy' or 'Tamoxifen' or 'Aromatase Inhibitors,' 'adherence,' or 'barriers.' The search was restricted to past six years. The abstracts of each result were reviewed and categorized as either patient-reported or physician-reported. All patient- and physician-reported factors that affected adherence and persistence were listed and grouped together into the three main categories: Socio-demographic and medical parameters, general psychosocial parameters, and psychosocial parameters related to OET.

A total of 320 articles were identified, of which 19 met inclusion criteria. Adverse drug reactions were the most commonly reported barrier but were generally underreported among physicians. Among patient-reported barriers, common social-demographic and medical parameters were age, comorbidity, and financial status. General psychosocial variables were lack of patient-provider communication, depressive symptoms, and lack of perceived self-efficacy. Treatment toxicity was the most commonly reported psychosocial parameter related to OET.

The determinants of non-adherence and non-persistence are multi-dimensional and influenced by several factors. The three categories of adherence barriers should be evaluated and considered when designing future interventions to enhance OET adherence for a tailored approach.