OBJECTIVES:  Since 2010, HER2 status has been reported to the Surveillance Epidemiology and End Results (SEER) registry for breast cancer (BC) cases. Previous research reported variations in adherence to guideline recommended treatment of early stage breast cancer (ESBC) that were associated with different receptor subtypes and race/ethnicity. This study sought to characterize associations between early stage breast cancer treatment patterns and joint receptor subtype, race/ethnicity, and insurance status. METHODS:  Females diagnosed with Stage I-II BC from 2010-2013 were identified in the SEER database based on availability of joint receptor subtype data. This population included patients diagnosed at ages 18-64 and excluded patients missing key information about demographics, tumor characteristics or treatment. Patients were classified as having received or not received guideline-concordant locoregional treatment (GCT) based on receipt of surgery and radiation per NCCN guideline recommendations. Multivariate logistic regression models identified factors associated with receiving GCT. RESULTS:  The final sample included 74,047 patients from 18 SEER registries. Patients were 67% non-Hispanic white, 11% African American, 10% Asian/Pacific Islanders, and 12% Hispanic white. Two percent were uninsured, 12% were Medicaid beneficiaries, and 85% were insured, non-Medicaid. The prevalence of receptor subtypes at diagnosis was 11% HER2+/HR+, 4% HER2+/HR-, 72% HER2-/HR+, and 12% HER2-/HR-. Overall, 87% of patients received GCT. Insured, non-Medicaid patients were 76% more likely to receive GCT (OR 1.76, 95%CI:1.56-1.98) and Medicaid patients were 25% more likely to receive GCT (OR 1.25, 95%CI:1.10-1.42) compared to uninsured patients. Race/ethnicity of African American was associated with decreased likelihood of receiving GCT (OR 0.77, 95%CI:0.72-0.82). HER2-/HR+ status was associated with increased likelihood of receiving GCT (OR 1.46, 95%CI:1.37-1.55). CONCLUSIONS:  Insurance status, receptor subtype, and race/ethnicity were significantly associated with receipt of GCT for ESBC. More research is needed to examine how these relationships may be influenced by additional variables not included in the SEER database.