Abstract C59: Initiation of adjuvant hormonal therapy among uninsured stage I-III breast cancer patients treated in a safety-net healthcare system
Authors: Murphy Caitlin C. , Tiro Jasmin A. , Jean Gary , Balasubramanian Bijal A. , Higashi Robin T. , Le Brian , Teng Hugh , Alvarez Carlos A. 
Published: May 2016

Background: Adjuvant hormonal therapy (AHT) significantly improves the overall and disease-free survival of breast cancer patients with hormone receptor-positive disease. Despite the benefits of AHT, many patients do not initiate or complete therapy as recommended. Further, adherence and patterns of AHT use in low-income and minority populations has not been well-studied. This study 1) estimated the prevalence of AHT initiation among breast cancer patients receiving care at a large safety-net healthcare system from 2008 to 2012; and 2) examined patient sociodemographic, tumor/treatment, and health history characteristics associated with AHT initiation.

Methods: Patients diagnosed with stages I-III hormone receptor-positive breast cancer were identified from an academic cancer registry at Dallas' Parkland Health and Hospital System (Parkland), one of the largest integrated safety-net healthcare systems in the U.S. We excluded patients who had a prior diagnosis of breast cancer, previously used AHT, did not receive definitive treatment and/or cancer-directed surgery at Parkland, or had commercial or Medicaid insurance. Uninsured residents of Dallas County are eligible for Parkland HEALTHplus, an income-based medical assistance program that covers prescriptions filled and dispensed by Parkland outpatient pharmacies. In addition, Parkland oncology and primary care clinics use the same, comprehensive electronic medical record (EMR). Thus, Parkland's payor and clinical informatics infrastructure provides a unique opportunity to examine initiation of AHT in uninsured, low-income, and minority populations. We extracted and linked pharmacy claims, cancer registry, and patient EMR data to determine the prevalence of AHT Initiation. Initiation was defined as a new AHT prescription within 18 months of the incident breast cancer diagnosis. Descriptive statistics were used to examine characteristics of the study population by AHT initiation, and log-binomial regression was used to identify correlates of initiation.

Results: We identified 291 breast cancer patients eligible for the study. Most patients were Hispanic (42.6%), not married (66.3%), and postmenopausal (63.9%). The mean age was 52.9 years. The majority (72.2%) of patients had one or more comorbid conditions, and the most prevalent comorbidities were hypertension (51.2%), hyperlipidemia (25.1%), and diabetes (20.3%). Overall, 239 (82%) patients initiated AHT within 18 months of diagnosis, and 52 (18%) did not initiate therapy. Among initiators, tamoxifen (42.3%) and anastrozole (55.2%) were the most commonly prescribed types of AHT. The mean retail price of tamoxifen and anastrozole was $126.80 and $472.20, respectively, with a mean copay of $4.90 for tamoxifen and $6.00 for anastrozole. In univariable analysis, patients who were Hispanic (RR 1.29, 95% CI 1.04—1.61) and other (RR 1.31, 95% CI 1.02—1.68) race/ethnicity, diagnosed in year 2008 (vs. 2012, RR 1.24, 95% CI 1.07—1.44), and received primary care at Parkland prior to diagnosis (RR 1.14, 95% CI 1.01—1.28) were more likely to initiate AHT. Current smokers (vs. never, RR 0.78, 95% CI 0.65—0.94) were less likely to initiate AHT. No variables remained statistically significant in the final multivariable model.

Conclusion: This study is an important first step in understanding AHT adherence behaviors in low-income and uninsured breast cancer patients. Our results suggest the majority of patients receiving care in a safety-net setting initiate AHT, and there are few differences in initiation by patient characteristics. Safety-net systems that provide access to AHT (e.g., through reduced prescription copays) may have a positive impact on disparities in AHT initiation rates among breast cancer patients. Future work is needed to determine if pharmacy benefits improve completion of the AHT regimen.

Citation Format: Caitlin C. Murphy, Jasmin A. Tiro, Gary Jean, Bijal A. Balasubramanian, Robin T. Higashi, Brian Le, Hugh Teng, Carlos A. Alvarez. Initiation of adjuvant hormonal therapy among uninsured stage I-III breast cancer patients treated in a safety-net healthcare system. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C59.