Adherence Barriers to Oral Endocrine Therapy Among Breast Cancer Patients



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Breast cancer is the most common type of cancer among women and the 2nd most prevalent cause of cancer deaths in women in the United States. Approximately 70-80% of all breast cancer express hormone receptors (HR) and are called HR-positive (HR+) breast cancer. For HR+ breast cancer, the standard systematic therapy is endocrine therapy (ET) which include selective estrogen receptor modulators like Tamoxifen, and aromatase inhibitors to inhibit the estrogen synthesis. For patients diagnosed with early-stage HR+ breast cancer, ET reduces breast cancer recurrence, metastasis, and mortality. The clinical benefit of ET is maximized when ET is taken daily for 5-10 years. Despite the well-documented clinical benefit of ET, nearly 50% of breast cancer survivors taking ET are non-adherent and 70% discontinue therapy before the recommended 5year. Low adherence and early discontinuation are associated with an increased risk of mortality, enhanced medical costs and lower quality of life years. The determinants of non-adherence and non-persistence are multi-dimensional and should be considered when designing interventions to enhance adherence.