Background: In Mexico 60% of newly diagnosed BC patients present with locally advanced disease. In the United States, 88-95% of patients present with early stage disease, however in Mexico, only 10% of patients are diagnosed at this stage. The Seguro Popular (SP), a national insurance scheme for Mexico's poor and uninsured population, was implemented for BC in 2007. The SP covers diagnostics, local and systemic treatment for BC patients. The INCMNSZ is a third level hospital where patients receive diagnosis and treatment for non-malignant diseases, and also routinely conducts BC annual mammography screening for women ≥ 50 years old. We aimed to evaluate BC outcomes in our patients following the implementation of SP at our institution. Methods: From January 2011 to May 2013, we prospectively evaluated a cohort of 93 patients with BC included in the SP program at the INCMNSZ. A retrospective cohort of 99 patients without SP access who received neoadjuvant chemotherapy from January 2007 to December 2009 was used for comparative analysis. Complete pathologic response (pCR) was defined as complete absence of invasive tumor in breast and axillary nodes. We used Fisher's exact test to compare pCR between groups. Results: A total of 93 patients were diagnosed with BC and included in the SP program. 10 patients were excluded from the analysis- (5 were lost to follow-up and 5 had missing data. Median age was 52 (46-59) years and 37 patients (45%) were premenopausal at diagnosis), median follow up 11.8 months. 20 patients (24%) had stage I, 36 (43%) stage II, 7 (8%) stage III, and 20 (24%) stage IV. 55 (66%) patients had hormone receptor (HR) positive (ER + and/or PR+), 15 (18%) HER2+ and 13 (16%) had triple negative (TN) tumors. Thirty-two (39%) patients received neoadjuvant chemotherapy. 27% of patients achieved pCR (17% in HR positive, 20% in TN and 50% in HER2+ tumors) compared to 15% in the non SP cohort (11% in HR positive, 22% in TN and 14% in HER2+ tumors). HER2+ tumors from the SP cohort reached significantly higher pCR rates than in the non SP cohort (p = 0.029). Discussion: Our results confirmed that about half of our patients were diagnosed with early stage BC, which highlights the importance of a screening program at our institution. Increased pCRs in the HER2+ subgroup may reflect wider access to trastuzumab after implementation of SP. Although we acknowledge a short period of follow-up in our cohort, our results in pCR are comparable to those previously reported in the literature. We believe the SP had a positive impact on access to care and outcomes in our patients. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-09-08.