12139 Background: Monitoring symptoms during chemotherapy is crucial as patients experience adverse effects, requiring therapeutic modifications, supportive care, and education. Patient navigation provides individualized assistance, overcoming barriers to healthcare access for patients, families, and caregivers. A previous study (Tabriz et al. JAMA Netw Open 2023) has shown that 52% of emergency room (ER) visits can be preventable. Thus, this study sought to determine effect of a nurse navigation program on reducing the rate of ER visit. Methods: This retrospective study was conducted from June to December 2023 in two cancer centers within the Oncoclinicas Network, located in the Southeast and Northwest regions of Brazil. Eligible patients were diagnosed with breast, lung, and gastrointestinal cancer, and were undergoing treatment with chemotherapy and/or immunotherapy. These patients were monitored by nurse navigators at post-therapy. Interventions were categorized as home management (care provided at patient’s home), outpatient (referral to the treatment clinic), and hospital (referral to emergency care). All toxicities were graded according to the Common Terminology Criteria for Adverse Events 5.0. Results: A total of 531 patients were included in the analysis, with the majority aged over 61 years old (44.4%), diagnosed breast (%) or colon (%) cancers. Throughout the six month study period, 3,201 toxicities were identified, with the majority graded between 1 and 2 (95.9%). This resulted in 91.9% of patients being managed at home or referred to the outpatient care. The cumulative proportion of patients having their symptoms managed at home or outpatient care is significantly higher than historical controls (P=0.001). Conclusions: Our findings highlight the effectiveness of a nurse navigation program in managing toxicities and symptoms, preventing ER visit. These findings underscore the importance of this program in optimizing patient care and reducing the burden on healthcare facilities. Further research and implementation of such programs may contribute to improved outcomes and patient satisfaction in oncological care.