Abstract Background: Patients with cancer, both active and previously treated, are at a higher risk of developing severe outcomes from COVID-19. During the pandemic, health care systems (HCS) have adapted the delivery of care, and disparities between private and public systems became even more striking. In Brazil, where 70% of the population depends on the public system, ICU demands largely exceed the capacity in most public centers, whereas in private centers the situation is less challenging. Herein we compare outcomes of patients with cancer and COVID-19 treated in the public and private HCS in Brazil. Methods: We used data from adult patients with solid malignancies who tested positive for COVID-19 and were admitted to two tertiary centers in the state of São Paulo. Patients who tested positive for SARS-CoV2 RNA real-time polymerase chain reaction (RT-PCR) were included. We collected data on baseline clinical conditions, cancer and treatment. Patients were classified by HCS: public system (public) versus (vs) private insurance coverage (private). The co-primary endpoints were all-cause mortality and a composite endpoint consisting of intensive-care-unit (ICU) admission, mechanical ventilation or death (ICU-MV-D). Chi-square, Fisher´s exact test and Mann-Whitney U test were used when appropriate. We assessed the association between outcomes and HCS using logistic regression analyses, adjusting for age, sex, current anticancer treatment and comorbidities. Results: From March 16 to October 20 2020, 124 patients were identified. Of those, 90 (72%) were from the public and 34 (28%) from the private HCS. There were no statistical differences in sex, smoking, primary tumor siteand staging between patients from both HCS. Conversely, patients treated in the private system were older [66 (SD 13.8) vs 74 (SD 15.1), p=0.004], had more comorbidities (64.7% vs 37.8% p=0.009), and were on anticancer treatment more frequently (64.7% vs 34.4% p=0.004) compared to public patients. There were no differences in all-cause mortality (public 40% vs private 44.1% p=0.69) between patients treated at the different HCS. Nevertheless, in the composite outcome, private system was significantly associated with increased risk of ICU-MV-D compared to the public system (79.4% and 57.8% p=0.030, respectively). The median time from COVID-19 diagnosis to ICU-MV-D was 13 vs 8 days (p=0.031) and to death was 25 vs 24 days (p=0.24), respectively for public and private HCS patients. In the multivariable logistic regression, HCS was not associated with death [adjusted odds ratio (aOR)=1.16 p=0.75] or ICU-MV-D (aOR=0.55, p=0.27). Conclusion: While patients in the private system were older and had more comorbidities, there were no differences in inpatients all-cause mortality between private and public systems. However, private patients were associated with increased ICU-MV-D. We hypothesize that these findings may reflect disparities in ICU availability, known to be higher in the private system. Further studies investigating this hypothesis are warranted. EDR and DVA co-senior authors. Citation Format: Marina Topanotti, Larissa L. Furlan, Catarina Marchon, Pedro Amaral, Barbara C. Beneton, Luiza A. Fadul, Maria Lucia Salomao, Suzana M. Lobo, Aline F. Fares, Daniel V. Araújo, Eliza D. Ricardo. Health care disparities and outcomes of cancer patients with COVID-19: A pooled analysis of two Brazilian tertiary centers [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P34.