Abstract Background: Breast cancer (BC) is the most common malignancy and one of the leading causes of cancer death in women in Latin America (LATAM). Studies have highlighted the importance of understanding contextual characteristics of each patient population to inform health policy-making. However, few data are available on women from LATAM, a region with marked inequalities. Methods: LATINA (LACOG 0615/MO39485) is a multicenter prospective cohort study designed to describe sociodemographic characteristics, diagnosis, treatment, and outcomes of patients with BC in LATAM. Female and male patients aged ≥18 years newly diagnosed (i.e., < 12 months from research site activation) histologically confirmed clinical stage I-IV BC were enrolled. Eligible patients provided informed consent and had data collected from medical records at diagnosis and every 6 months up to 5 years. Results: Between February 2020 and August 2022, 3276 patients with BC from 31 research sites in 10 LATAM countries were included. Median age was 54 years (range 23–95), 91.8% (N=3008) were Hispanic or Latinos, the majority (68%, N=2224) were diagnosed with stage II or III BC, and 73% (N=2362) were treated in the public health system. Age, stage and detection method stratified by education level, marital status and employment status are shown in Table 1. Overall, 38.8% (N=1149) of patients had not completed high school. These patients were more frequently diagnosed by symptoms and diagnosed at later stages than those who had completed high school or college. Half of the patients were married/in a civil partnership at BC diagnosis (50.5%, N=1497). Unmarried patients were more commonly diagnosed by symptoms (71.7%, N=835 vs. 64%, N=916, p< 0.001) and with stage II/III BC (71.4%, N=868 vs. 67.6%, N=1038, p< 0.001) than married patients. Most patients (54.1%, N=1603) were not employed at BC diagnosis. Patients not employed were more frequently diagnosed by symptoms (68.8%, N=1044) than employees/self-employed (61.6%, N=675). After adjusting for age, country, health care provision (public or private), stage, and BC subtype, being diagnosed by symptoms was associated with not being married (adjusted odds ratio [aOR] 1.41, 95% CI 1.11–1.82, p=0.004), being not employed (aOR 1.41, 95% CI 1.08–1.84, p=0.011), and not having completed high school (aOR 1.46, 95% CI 1.00–2.13, p=0.031). Conclusions: Patients with a lower level of education, unmarried and not employed, are more likely not to perform BC screening and to be diagnosed by symptoms. Socioeconomic characteristics impact the method of detection of BC in LATAM and are associated with diagnosis at later stages. Further analyses of the LATINA study will provide invaluable data for informing regional health policy-making in LATAM. Citation Format: Gustavo Werutsky, Cynthia Villarreal-Garza, Henry Gómez, Juan Manuel Donaire, José Bines, Luis Henrique Fein, Maria Clara Horsburgh, Paula Cabrera-Galeana, Heloísa Resende, Rosa Vasallo Veras, Miriam Raimondo, Ricardo Elías Brugés Maya, Vidal Maria Del Rosario, Yeni Nerón, Ana Maria Donoso, Fernanda B. Damian, José D'Oliveira, Couto Filho, Maria Isabel Alonso, Victoria Costanzo, Tomás Reinert, Adriana Elizabeth Borello, Eduardo Cronenberger, Luis Fein, Marcela Urrego, Enrique Alanya, Jorge Luis Soriano García, Saúl Campos-Gomez, Eduardo A. Richardet, Hugo Castro-Salguero, Felipe Cruz, Diego Gómez, Angel Hernández, Carlos Alberto Farfan Tello, Ronald Rodríguez, Rafaela Jesus, Gustavo Gössling, Carlos Barrios. The Impact of Socioeconomic Factors on Breast Cancer Diagnosis in Latin America: The LATINA study (LACOG 0615/MO39485) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-10-05.