Identification of factors associated with non-adherence to oral endocrine therapy in breast cancer patients of low socioeconomic status: a single centre retrospective study.

[INTRODUCTION] The standard treatment for Hormone Receptor-Positive breast cancer (BC) is Oral Endocrine Therapy (OET). OET reduces BC recurrence rates by ~ 50%, and non-adherence to OET leads to worse outcomes. However, OET adherence remains suboptimal, particularly among low socioeconomic status populations.

[AIM] This study assessed 12-month OET adherence and identified factors associated with non-adherence among BC patients at a multispecialty hospital in Edinburg, Texas in the Rio Grande Valley region.

[METHOD] A 12-month single-center retrospective study of BC patients taking OET was conducted. Information on patient demographics, tumor characteristics, and prescription details was gathered from electronic medical records. Inclusion criteria included patients 18 years or older who filled at least one OET prescription. OET adherence was assessed using the proportion of Days Covered. Differences between the adherent and non-adherent groups were analyzed using chi-square and Student's t-tests, while multivariable logistic regression was employed to identify factors associated with non-adherence.

[RESULTS] Of the total 346 adult female patients, 322 (93%) were Hispanic/Latino. The mean age was 60.8 years, and the mean body mass index was 30.7. Only 122 (35.3%) patients were adherent at 12 months. Patients with diabetes were less likely to be adherent (odds ratio, 0.44; 95% confidence interval: 0.25-0.80). Longer duration of therapy was associated with higher OET adherence, which was estimated to increase 1.84-fold with each additional year of therapy.

[CONCLUSION] Approximately two-thirds of BC patients were non-adherent to OET. Diabetes and shorter time on therapy predicted poorer adherence. These results present the urgent need to address barriers to OET adherence among BC patients in the underserved area of South Texas.