Abstract 2617: Factors associated with utilization of post-mastectomy adjuvant therapies in privately insured female patients with early-stage invasive breast cancer
Authors: Arriaga Yull , Tkacz Joseph , Roebuck M Christopher , George Judy , Willis Van , Dankwa-mullan Irene 
Published: July 2021

Background: In a commercially insured cohort of female patients with early-stage invasive breast cancer we examined geographic and clinical factors associated with variation in uptake of post-mastectomy adjuvant endocrine therapy (AET), cytotoxic chemotherapy (ACT) and biologic therapy (ABT).

Methods: Retrospective observational study of the IBM® MarketScan® claims data from 01/01/2012-03/31/2018. Eligibility criteria included: 1) diagnosis of non-metastatic invasive breast cancer in female patients 18 years old or older, 2) mastectomy within 6 months of initial diagnosis. Patients with breast carcinoma in situ only and those who received neoadjuvant therapies were excluded. Multivariate logistic regression was used to identify factors associated with receipt of adjuvant therapy, including: 1) age, insurance plan type, and select chronic comorbid conditions, 2) sociodemographic, community-level (ZIP3) measures obtained from the 2019 Area Health Resource Files, and 3) time effects. Analyses were conducted at the patient level with standard errors clustered by ZIP3.

Results: Of the 16,680 patients identified, 5,341 (32%) received AET only, 2,290 (14%) received ACT only and 729 (4%) received ABT. 7,911 (47%) did not have any claims for adjuvant therapy. 3% received adjuvant combinations, mostly post-radiation treatment (2%). We observed the following statistically significant associations (p&lt;.001 to p&lt;.05) between selected variables and adjuvant therapy use:- Increasing age and higher likelihood of AET (1.2-1.8) but decreased likelihood of ACT (.8-.03) and ABT (.98-.24).- Primary health policy holders were 13% more likely to receive ACT compared to a spouse or other dependent.- Patients residing in the Midwest and higher likelihood of receiving AET (OR=1.15), ACT (OR=1.14), and ABT (OR=1.44) compared to those in the Northeast whereas those in the West and South had higher likelihood of receiving ACT (OR=1.31; OR=1.21), and ABT (OR=1.66; OR=1.36).- Patients residing in areas with increased Black resident density (ZIP3 level) and lower likelihood of receiving AET (OR=.58), ACT (OR=.61), and ABT (OR=.45).- Percentage population with a 4-year college degree and decreased likelihood of ACT (OR=.33).- Genetic testing and increased likelihood of AET (OR=1.92), ACT (OR=2.72), and ABT (OR=1.91).- Breast carcinoma in situ diagnosis preceding invasive disease diagnosis and decreased likelihood of receiving AET (OR=.56), ACT (OR=.2) and ABT (OR=.65).

Conclusions: In a large cohort of commercially insured patients with early-stage invasive breast cancer, uptake of post-mastectomy adjuvant therapies varied and was influenced by several non-clinical factors. Results of real-world evidence cancer studies may support treatment-decision making, guide adoption of value-based care models and reduce treatment disparities.

Citation Format: Yull Arriaga, Joseph Tkacz, M Christopher Roebuck, Judy George, Van Willis, Irene Dankwa-mullan. Factors associated with utilization of post-mastectomy adjuvant therapies in privately insured female patients with early-stage invasive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2617.