Abstract P5-14-16: Factors associated with endocrine therapy refusal in hormone receptor-positive breast cancer patients
Authors: Advani Pooja P , Guzman Ricardo Torres , Verduzco Francisco Avila , Maita Karla , Garcia John , Eldaly Abdullah , Forte Antonio , Spaulding Aaron 
Published: March 2022

Abstract
Background: Endocrine therapy (ET) reduces breast cancer (BC) recurrence risk and improves BC outcomes. However, patients (pts) may refuse ET, potentially impacting their outcomes. However, the exact incidence and factors associated with ET refusal are largely unknown. Methods: We conducted a retrospective study of BC pts in the National Cancer Data Base between 2003 and 2017. Demographic, socioeconomic, co-morbidity index and tumor-specific data were compared between BC pts who refused ET versus those who agreed to ET using bivariate and multivariate models. Female pts 18 to 89 years of age with stage I, II, and III were included. Logistic regression was used to determine associations with ET refusal. Results: Among 463,228 pts, the incidence of ET refusal was 5.26% (24, 401). Of these pts, 85% were non-Hispanic White, 7.9% were Non-Hispanic Black, 3.1% non-Hispanic Asian/pacific islander, and 3.6% were Hispanic. A majority (56.9%) had government insurance, and 87.2% were from a metro residential area. Infiltrating ductal carcinoma BC subtype comprised 78% of pts. Most pts were 51-89 years of age (80%), and 20% were 18-50 years of age. On multivariable analysis (Table 1), non-Hispanic black (OR 0.82), non-Hispanic Asian (OR 0.72), and Hispanic (OR 0.84) pts had a reduced odds of refusing ET than non-Hispanic white pts. Pts with government insurance (OR 1.6, p&lt;0.001) and noninsured pts (OR 1.3, p&lt;0.001) had increased odds of refusing ET compared to privately insured pts. Estrogen receptor (ER) -/Progesterone (PR) +, and ER +/PR - had increased odds of refusing therapy (OR 2.9, and 1.1 respectively, p&lt;0.001) than ER +/PR + pts. Patients with positive lymph nodes had reduced odds of refusing ET than those with negative lymph nodes (p&lt;0.001). Additionally, pts with a 2.1-5 cm (OR 0.92) or &gt;5 cm (OR 0.87) tumor size had a reduced odd of refusing ET than those with tumors less than 2 cm (p&lt;0.001). Finally, patients with well-differentiated BC (grade I) had increased odds of refusing ET (OR 1.2, p&lt;0.001) than moderately differentiated (grade II) BC. Conclusions: The incidence of ET therapy refusal is relatively low; however, survival outcomes may be negatively impacted. This is the first study to evaluate specific demographic and disease-specific factors associated with ET refusal, which can inform strategies to improve ET acceptance rate.
Table 1.Multivariable Logistic Regression – ET Therapy Acceptance (Referent) vs. Refusal.VariableOR95% CIp-valueAge51 - 89 years18 - 50 years0.940.900.970.001Race/EthnicityWhite Non-HispanicBlack Non-Hispanic0.820.760.88&lt;0.001Pacific Islander Non-Hispanic0.720.660.76&lt;0.001Hispanic0.840.790.87&lt;0.001InsurancePrivateGovernment1.61.521.61&lt;0.001Not insured1.31.181.47&lt;0.001ResidenceMetroUrban0.900.870.87&lt;0.001Rural0.870.780.970.014HistologyInfiltrating ductal carcinomaLobular carcinoma0.840.800.87&lt;0.001Infiltrating duct and lobular carcinoma0.900.850.95&lt;0.001Others1.171.101.24&lt;0.001Positive Nodes01 - 30.620.600.65&lt;0.0014 - 90.610.570.66&lt;0.00110 +0.610.550.68&lt;0.001VariableOR95% CIp-valueER/PR ExpressionER +/PR +ER -/PR +2.92.563.18&lt;0.001ER +/PR -1.11.061.14&lt;0.001Tumor size≤ 2 cm2.1 - 5 cm0.920.880.94&lt;0.001&gt; 5 cm0.870.800.93&lt;0.001GradeIII1.211.181.25&lt;0.001III0.980.951.020.518Charlson-Deyo Score010.940.910.980.00421.070.991.150.071≥31.120.981.280.079
Citation Format: Pooja P Advani, Ricardo Torres Guzman, Francisco Avila Verduzco, Karla Maita, John Garcia, Abdullah Eldaly, Antonio Forte, Aaron Spaulding. Factors associated with endocrine therapy refusal in hormone receptor-positive breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-14-16.