[Acute tumor lysis syndrome in the setting of advanced gastric cancer].

A 69-year-old man was admitted with right flank pain. The patient was diagnosed with advanced gastric cancer with multiple metastases in the liver and abdominal lymph nodes and underwent chemotherapy. Three days following the initial administration of S-1 plus cisplatin, the patient developed tumor lysis syndrome (TLS) with increased LDH, hyperuricemia, hyperkalemia, and elevated creatinine. Although rare, TLS following chemotherapy for solid tumors is a potentially fatal complication, and high physician awareness is required, especially in patients with risk factors, such as bulky disease.