Background: Breast Conserving Surgery (BCS) is now considered an acceptable alternative to mastectomy for patients with early stage invasive breast cancer (ESBCa). Limited research examining factors influencing choice of BCS reveal important predictors such as insurance, sociodemographic characteristics, and availability of health care services. While most studies were conducted in largely single-state or limited cohorts, this contemporary study examined factors associated with BCS choice in a cohort of commercially insured females with ESBCa. Methods: This retrospective observational study of the IBM® MarketScan® claims data spanned 01/01/2012 to 03/31/2018. Eligibility criteria included: 1) diagnosis of invasive breast cancer, 2) absence of metastatic or other primary/secondary cancers, and 3) BCS or mastectomy within 6 months of initial diagnosis. Predictors of BCS were examined using logistic regression, which included: 1) patient-level factors of age, BRCA 1/2 testing, insurance plan type, and comorbid conditions, 2) community-level (ZIP3) measures from 2019 Area Health Resource Files, and 3) time effects. Results: A total of 57,299 patients were included. Higher BCS use (versus mastectomy) was significantly associated with: more recent year of diagnosis (OR: 1.08-1.72, p<.0001-p=.02), older age (OR: 1.96-2.44, p<.0001), genetic testing (OR: 1.25, p<.0001), radiation pre-surgery (OR: 4.20, p<.0001), and higher density of physicians in specialties of medical genetics (OR: 6.50, p<.01) or nuclear medicine (OR: 2.24, p=.04). Lower BCS use was associated with: comorbid dementia (OR: 0.58, p=.01), comorbid congestive heart failure (OR: 0.79, p=.01), chemotherapy pre-surgery (OR: 0.40, p<.0001), residing in the South, Midwest, or West (OR: 0.71-.89, p<.0001-p=.01), and a greater availability of either plastic surgeons (OR: 0.66, p<.0001) or hospitals with medical/surgical services (OR: 0.26, p<0.01). Few patients had radiation pre-surgery (1.25%), but those patients had increased use of BCS. Conclusions: Choice of BCS over mastectomy increased over time. This study showed increased adoption with older age, access to and use of genetic services, pre-operative radiation and decreased use with certain co-morbid conditions and the regions of the South, Midwest, or West. This real-world study contributes to informing clinical practice on the significant patient- and community-level factors influencing BCS in an ESBCa cohort.
