Abstract PO-114: Initiation and adherence to adjuvant endocrine therapy among urban, insured American Indian/Alaskan Native breast cancer survivors

Abstract

Abstract Background: Disparities in adjuvant endocrine therapy (AET) initiation and adherence have been shown by race/ethnicity, however the relationship among American Indian/Alaskan Natives (AIAN) is poorly understood, particularly among the 73% of urban residing AIAN. We evaluated whether AET-initiation and adherence were lower among AIAN than other races/ethnicities enrolled in Kaiser Permanente of Northern California (KPNC) health system. Methods: We identified 23,680 AET- eligible (first primary, stage I-III, hormone receptor-positive breast cancers) patients from 1997 to 2014 and used KPNC’s pharmacy records to identify AET-prescriptions and refill dates. We assessed AET-initiation (≥1 filled prescription within 1-year of diagnosis) and AET-adherence (proportion of days covered [PDC] ≥80%) every year up to 5-years post AET-initiation. Results: At the end of the 5-year period, 83% were AET-initiators and 58% were AET-adherent. Compared to all other races/ethnicities, AIAN women had the second lowest AET-initiation (Black=78.0%, AIAN=78.6%, Hispanic=83.0%, non-Hispanic white [NHW]=82.5%, Asian=84.7%), the lowest AET- adherence by the end of the 1-year and 5-year period (70.3% and 50.8% vs. NHW=76.4% and 58.8%, respectively), and the greatest AET-discontinuation in year period 4 to 5 (13.8% AET-adherence decrease, 64.6% to 50.8%), after AET-initiation. In the multivariable models adjusting for age, socioeconomic and clinical factors, AIAN, Hispanic, and Black women were less likely than NHW women to be AET- adherent although the number of AIAN was small leading to imprecise estimates. At the end of the 5-year period, total underutilization (combining initiation and adherence) in AET-eligible was greatest among AIAN (70.6%), followed by Black (69.6%), Hispanic (63.2%), NHW (58.7%), and Asian (52.3%), underscoring the AET- treatment gap. Conclusion: Our results suggest that AET-initiation and adherence are particularly low for insured AIAN women. Results suggest that interventions are needed, even for urban, insured AIAN women who tend to have greater geographic access and fewer financial issues than their rural counterparts. Citation Format: Marc A. Emerson, Ninah Achacoso, Halei C. Benefield, Melissa A. Troester, Laurel A. Habel. Initiation and adherence to adjuvant endocrine therapy among urban, insured American Indian/Alaskan Native breast cancer survivors [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-114.