Abstract A138: Evaluating medication adherence of oral endocrine therapy among breast cancer survivors in a large academic medical center

Abstract

Abstract Introduction: Clinical guidelines suggest maximum benefit of oral endocrine therapy (OET) for hormone receptor-positive breast cancer (HR+ BC) when taken for five to ten years. Despite benefits of improved outcomes, more than half of the breast cancer survivors are non-adherent to OET. The objective of this study was to evaluate the adherence of OET for HR+ BC survivors of different race and ethnicity at 6- and 12-months using Houston Methodist Hospital (HMH) electronic medical records (EMRs). Methods: A single-center, retrospective, observational study was conducted. EMRs were collected for survivors with OET prescriptions at the HMH outpatient center from May 2018 through December 2018. Adherence rates using proportion of days covered (PDC) were calculated at 6- and 12-months interval. Adherence was defined as PDC ≥ 0.8 while non-adherence was defined as PDC < 0.8 and was the outcome variable. Descriptive statistics were conducted, and differences between adherent and non-adherent groups were assessed using chi-square and student’s t-tests. Separate multivariable logistic regression models were used to assess the predictors of adherence at 6 and 12 months controlling for demographic and clinical characteristics. These included age, ethnicity, cancer stage, type of endocrine therapy, duration of therapy, and switch of therapy. Results: A total of 338 survivors on OET were identified. At 6-months, 82% of survivors (n=277) were adherent. At both 6-and 12 months the adherent group mainly comprised of Caucasians (68%) and African American (14-16%) survivors. In the multivariable logistic model for 6-months, survivors on tamoxifen were 52% less likely to be adherent to OET as compared to survivors on aromatase inhibitors (OR 0.48; 95% CI 0.24-0.95). Similarly, survivors on OET therapy for 3-5 years were significantly associated with lower adherence as compared to survivors on OET therapy for less than or equal to 2 years (OR 0.29; 95% CI 0.09-0.91). Although not significant, survivors of Hispanic origin were less likely to be adherent to OET as compared African Americans (OR 0.37; 95% CI 0.12-1.09). Of the 237 survivors included in the 12 months analysis, 78.9% (n=187) were adherent at 12 months. None of the variables showed a significant association with adherence at 12 months due to smaller sample size. Conclusion: Adherence rates decreased from 6-to 12 months. Type of OET therapy and duration of therapy were significantly associated with adherence at 6-months. Future longer-term multi-center studies with more patients from diverse ethnicity, race, and socioeconomic status will elucidate mechanisms of cancer health disparity in OET adherence. Citation Format: Rutugandha Paranjpe, Grace Hwang, Carine Opsomer, Kelvin Lu, Uzo Abajue, Hanna Zaghloul, Susan Abughosh, Meghana Trivedi. Evaluating medication adherence of oral endocrine therapy among breast cancer survivors in a large academic medical center [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr A138.