Abstract INTRODUCTIONPatients diagnosed with breast cancer (BC) in Brazil are on average 54 years old and the majority (70%) have stage II-III. Age and clinical stage have a negative impact on patient personal life and labor productivity. The socioeconomic status is a fundamental part of the population’s health, which includes marital and employment status. Our aim was to analyze the socioeconomic impact of BC diagnosis which is poorly studied in low or middle-income countries. METHODSThis is a cross-sectional study including patients from AMAZONA III cohort study. Eligible patients were female aged > 18 years with diagnosis of any stage invasive BC from 2016 to 2018 in 24 participating hospitals in Brazil. The present analysis evaluated the marital and employment status at baseline and at 1-year follow-up after BC diagnosis. Patients with missing data were excluded and women older than 60 years, retirement age in Brazil, were not included in this analysis. A multivariate Poisson regression analysis with robust variance was adjusted to assess which patients’ characteristics associated with job loss and relationship status. The characteristics evaluated were age (⇐ 50 vs. > 50 years), educational level (Illiterate to completed first degree or completed second degree vs. higher), personal income (no income – 2 minimum wages vs. 2 to 5 minimum wages vs. more than 5 minimum wages), clinical-stage (I-III vs. IV), molecular subtype (luminal, HER2 positive vs. triple negative), surgery type (breast conserving surgery vs. any type of mastectomy), and systemic treatment (chemotherapy vs. hormonal therapy vs. none). The significance level was set at 5%. All analyses were conducted using SAS version 9.4 (SAS Institute, Cary, NC). RESULTSFrom a total of 1257 patients with evaluable employment status, 655 patients (52.1%) had working activity at the time of BC diagnosis. After 1 year of follow-up, there was an absolute decrease of 5.3% in patients’ employment (52.1% to 46.8%; p= 0.0075). Loss of employment was higher in older patient > 50 years (8.7%), lower educational level (9.9%), those earning 2-5 minimum wages (11.2%), stage I-III (7%), triple negative (6.9%), mastectomy (9.9%) and treatment with hormone therapy (11%). Patients with higher educational level (RR 0.61, 95% CI 0.36-0.94, p=0.0265) were at lower risk of employment loss whereas patients with personal income of more than 2 minimum wages (RR 1.83, 95% CI 1.08-3.10, p=0.0236) and mastectomy (RR 2.16, 95% CI 1.47-3.17, p=0.0015) were at higher risk of being unemployed loss after 1 year of diagnosis. Other factors such as age, clinical stage, BC subtype and treatment were not independently associated with unemployment. A total of 1947 patients had marital status information at baseline. Of those, 1182 (60.7%) were married or in common-law marriage at BC diagnosis. After 1 year of follow-up, 52 (2.7%) of these women loss their relationship (60.7% vs. 58%; p=0.08). Loss of relationships was higher (5.2%) in younger patients (≤ 50 years), lower educational level (4.9%), no income or up to 2 minimum wages (5.4%), stage IV (7.7%), HER2 positive (5.5%), mastectomy (5.4%) and treatment with hormone therapy (5.5%). None of the variables evaluated such as age, educational level, personal income, clinical-stage, molecular subtype, surgery type and systemic treatment, were significantly associated with change of marital status for patients previously married or in common-law marriage. CONCLUSION The socioeconomic impact of BC diagnosis was minimal at 1-year follow-up in Brazil. Nonetheless personal income and surgery type were associated with higher chance of unemployment whereas no specific variables were related to marital status change. Government social policies specifically for work return remains critical for BC patients in short-term after BC diagnosis. Citation Format: Gustavo Werutsky, Daniela Dornelles Rosa, Carlos Barrios, Eduardo Cronemberger, Geraldo Queiroz, Jose Bines, Mahira Lopes Rosa, Rafaela Gomes, Ana P Heck, Laura Freitas, Arthur F da Silva, Matheus Rodrigues, Andre P Fay, Sergio Simon. The socioeconomic impact of breast cancer in Brazil: An analysis of AMAZONA III cohort study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-89.