Concurrent factors associated with adherence to adjuvant endocrine therapy among women with non-metastatic breast cancer

Purpose: Adjuvant endocrine therapy (AET) reduces breast cancer morbidity and mortality, yet women often report suboptimal adherence. Though correlates of AET adherence are well-documented, few studies examine the relative importance of multi-level factors associated with adherence. The aim of this study was to identify factors most strongly associated with AET adherence in women with breast cancer.

Methods: Between 10/2019 and 6/2021, women (N = 100) with non-metastatic, hormone receptor-positive breast cancer, taking AET who reported AET-related distress enrolled into a clinical trial. Participants completed baseline measures, including the Medication Adherence Rating Scale-5, sociodemographics, and validated measures of anxiety, depression, medication-taking self-efficacy, social support, and treatment satisfaction. We created a latent factor and tested associations between sociodemographic, medical, and psychosocial characteristics and adherence. Associated predictors (p < .10) were entered into a structural model, which was corroborated via multivariate regression modeling.

Results: A four-indicator latent adherence factor demonstrated good model fit. Participants (M_age = 56.1 years, 91% White) who were unemployed (B = 0.27, SE = 0.13, p = .046) and reported greater treatment convenience (B = 0.01, SE = 0.01, p = .046) reported greater adherence. Scores of participants who reported greater medication-taking self-efficacy (p = .097) and social support (p = .062) approached better adherence. Greater medication-taking self-efficacy (B = 0.08, SE = 0.02, p < .001) and being unemployed (B = 0.28, SE = .14, p = .042) were most strongly associated with greater adherence, independent of other predictors. Multivariate modeling confirmed similar findings.

Conclusions: Medication-taking self-efficacy and employment status were associated with AET adherence above other related factors.

Implications for cancer survivors: Enhancing patients' confidence in their ability to take AET for breast cancer may represent an important intervention target to boost adherence.