Abstract 1566: Guideline-concordant care among women with HER2 negative metastatic breast cancer: A SEER-Medicare analysis
Authors: Vyas Ami M. , Mantaian Tyler , Kogut Stephen J. 
Published: August 2019

Abstract
Objectives: Limited data exist regarding the rates of guideline-concordant care among women with HER2 negative metastatic breast cancer (MBC). The primary objective of the study was to determine the proportion of women with HER2 negative MBC who received guideline-concordant care and also its predictors using a multivariable framework.
Methods: A retrospective observational cohort study was performed using the Surveillance, Epidemiology, End Results-Medicare linked database. The study cohort consisted of women age ≥ 66 years diagnosed with HER2 negative MBC in 2010-2013. Guideline-concordant initial care within six months of cancer diagnosis was determined as per The National Comprehensive Cancer Network (NCCN) treatment guidelines. The Andersen behavioral model of healthcare services utilization was utilized to identify the significant factors that affect guideline-concordant cancer care. A multivariate logistic regression was performed to identify the significant predictors of guideline-concordant care in the study cohort, after controlling for predisposing, enabling, and need-related factors, healthcare use, and external environmental healthcare factors.
Results: Among 1,089 older women with HER2 negative MBC, 72.3% received guideline-concordant care, while 27.7% did not receive guideline-concordant care. Marital status and education among enabling factors, hormone status among need-related factors, and the number of oncology visits among healthcare use were significant predictors of guideline-concordant care for women with HER2 negative MBC. Compared to women who did not receive guideline-concordant care, women who received guideline-concordant care were significantly more like to have had positive hormone receptor status, be married, resided in census areas with the higher proportion of people age ≥ 25 years with at least years of education, and had the higher number of oncology visits. The adjusted odds ratios were 4.004 (95% confidence interval (CI)=2.726-5.881, 1.543 (95% CI=1.087-2.191), 2.180 (95% CI=1.111-4.278), and 4.908 (95% CI=3.313-7.270). Among predisposing factors, age at cancer diagnosis was a significant predictor of guideline-concordant care. The likelihood of receiving guideline-concordant care decreased for women who were at least 70 years of age at cancer diagnosis. The adjusted odds ratios were 0.573 for women in 70-74 years age group, 0.592 for women in 75-79 years age group, and 0.403 for women at least 80 years old (p&lt;0.0001).
Conclusion: Approximately 28% of older women with HER2 negative MBC were not treated as per the NCCN breast cancer treatment guidelines. These study findings have identified the opportunities to improve cancer care for older women at least 70 years of age at cancer diagnosis, who are single or divorced, and those with negative hormone receptor status.
Citation Format: Ami M. Vyas, Tyler Mantaian, Stephen J. Kogut. Guideline-concordant care among women with HER2 negative metastatic breast cancer: A SEER-Medicare analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1566.