Endocrine Therapy Nonadherence and Discontinuation in Black and White Women

Stephanie B. Wheeler; Jennifer Spencer; Laura C. Pinheiro; Caitlin C. Murphy; Jo Anne Earp; Lisa Carey; Andrew Olshan; Chiu Kit Tse; Mary E. Bell; Morris Weinberger; Katherine E. Reeder-Hayes

Disclosures

J Natl Cancer Inst. 2019;111(5):498-508. 

In This Article

Abstract and Introduction

Abstract

Background: Differential use of endocrine therapy (ET) by race may contribute to breast cancer outcome disparities, but racial differences in ET behaviors are poorly understood.

Methods: Women aged 20–74 years with a first primary, stage I–III, hormone receptor–positive (HR+) breast cancer were included. At 2 years postdiagnosis, we assessed nonadherence, defined as not taking ET every day or missing more than two pills in the past 14 days, discontinuation, and a composite measure of underuse, defined as either missing pills or discontinuing completely. Using logistic regression, we evaluated the relationship between race and nonadherence, discontinuation, and overall underuse in unadjusted, clinically adjusted, and socioeconomically adjusted models.

Results: A total of 1280 women were included; 43.2% self-identified as black. Compared to white women, black women more often reported nonadherence (13.7% vs 5.2%) but not discontinuation (10.0% vs 10.7%). Black women also more often reported the following: hot flashes, night sweats, breast sensitivity, and joint pain; believing that their recurrence risk would not change if they stopped ET; forgetting to take ET; and cost-related barriers. In multivariable analysis, black race remained statistically significantly associated with nonadherence after adjusting for clinical characteristics (adjusted odds ratio = 2.72, 95% confidence interval = 1.75 to 4.24) and after adding socioeconomic to clinical characteristics (adjusted odds ratio = 2.44, 95% confidence interval = 1.50 to 3.97) but was not independently associated with discontinuation after adjustment. Low recurrence risk perception and lack of a shared decision making were strongly predictive of ET underuse across races.

Conclusions: Our results highlight important racial differences in ET-adherence behaviors, perceptions of benefits/harms, and shared decision making that may be targeted with culturally tailored interventions.

Introduction

Nationally, breast cancer mortality is 41.5% higher among black women compared with white women, despite a historically lower incidence rate.[1] Racial differences in screening, stage at diagnosis, insurance status, and tumor biology explain some, but not all, of this disparity.[2,3] Although breast cancer in black women is characterized by higher estrogen receptor negativity, higher grade, and histological differences,[4–10] studies suggest that black women have worse prognoses regardless of subtype and biologic profile of disease.[11,12] In fact, the largest racial disparity in outcomes occurs within the biologically similar hormone receptor–positive (HR+), HER-2-negative subtypes, suggesting that treatment differences and other nonbiological factors may explain these racial differences.[11]

Failure to receive appropriate treatment[13–16] is an important cause of observed racial disparities in breast cancer mortality.[17,18] Black women are less likely to receive timely and guideline-recommended surgery, radiation, and endocrine therapy (ET).[19] Importantly, however, black and white women with clinically similar disease profiles can achieve similar outcomes under similar treatment modalities.[20,21]

Oral adjuvant ET is an important part of treatment for HR+ cancer, the majority of all breast cancer cases. Evidence suggests that taking ET for up to 10 years reduces the risk of recurrence and cancer-specific mortality.[22,23] However, between 15% and 49% of women with HR+ disease never initiate ET,[24–27] and more than half do not take ET as recommended,[28,29] with black women having lower medication usage (including taking medication as prescribed [adherence] and continuing to take medication at all [continuation]).[30] Reasons for nonadherence and discontinuation may differ by race. Beliefs about medication efficacy, patient–provider relationship, and level of social support have all been associated with ET underuse, but it is unknown if modifiable factors such as these are experienced differently by black and white women or whether correlates of nonadherence and discontinuation differ.[31]

The social-contextual framework considers the ways in which both health and health behaviors are influenced by one's social context, including access to care, material hardship, and social support.[32] It is essential to understand the complex social contextual predictors of ET nonadherence and discontinuation if we are to develop culturally sensitive interventions to reduce disparities in breast cancer outcomes. Existing literature provides snapshots of reasons for ET underuse, but fails to elucidate racial differences in associations.[27,33,34] We sought to extend this literature by examining to what extent ET-related side effects, perceptions of recurrence risk, and shared decision making explain black/white differences in nonadherence and discontinuation. Our analysis from a large, minority-enriched, longitudinal cohort study provides novel insights into ET adherence behavior by race and points to potential reasons why black women with HR+ disease may experience higher mortality.

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