Background <p>In the treatment of small cell lung cancer (SCLC), acute tumor lysis syndrome (ATLS) is one of the oncologic emergencies that requires particular attention. Previous studies have generally indicated that ATLS increases mortality risk during treatm ent. Therefore, early identification of ATLS, along with proactive prevention and symptomatic management, is particularly crucial.</p> Methods <p>In this report, we detail the clinical management of a patient with SCLC and multiple metastases who was identified as being at relatively high risk for ATLS due to a large tumor burden and concurrent liver and kidney dysfunction.</p> Results <p>Despite rapid tumor progression, the treatment team implemented aggressive hydration and urine alkalinization as pretreatment measures and personalized dose-reduced chemotherapy based on the standard EC regimen. Nevertheless, the patient developed ATLS, which progressed rapidly, and despite intensive treatment, the condition remained irreversible.</p> Conclusion <p>This case highlights that in some SCLC patients, pre-chemotherapy evaluation reveals a higher risk for tumor lysis syndrome, and adjusting treatment strategies for these patients requires further investigation. This suggests that managing such high-risk patients in clinical practice requires more cases and optimized treatment strategies to guide management. Therefore, this case is presented to offer insights into this perspective.</p> Clinical trial number <p>Not applicable.</p>