Tumor Lysis Syndrome After mFOLFOX6 Administration for Ascending Colon Cancer.

Tumor lysis syndrome (TLS) is an oncologic emergency characterized by massive tumor cell lysis accompanied by the excessive release of large amounts of intracellular electrolytes and metabolites into the bloodstream. TLS is a potentially life-threatening condition that can lead to acute kidney injury, seizures, and sudden death due to arrhythmias. Therefore, prophylactic measures and prompt therapeutic intervention are essential for its management. TLS in solid tumors is extremely rare and has been documented only in a limited number of case reports. To our knowledge, three previous cases of TLS with colorectal cancer undergoing chemotherapy have been reported in the literature. We successfully treated a patient who developed TLS following modified FOLFOX6 (mFOLFOX6) therapy. The patient had ascending colon cancer with liver metastasis and right ureteral invasion and underwent colostomy before the initiation of mFOLFOX6. The presence of liver metastasis and elevated lactate dehydrogenase (LDH) levels on pre-treatment blood tests was considered a risk factor for the development of TLS. Therefore, blood tests were performed on day three after the initiation of mFOLFOX6 therapy, which revealed the onset of TLS. Prompt treatment with intravenous hydration, administration of diuretics, and oral febuxostat led to rapid improvement in serum uric acid, potassium levels, and renal function, allowing successful management without progression to a severe situation. This case further emphasizes that early identification and treatment of TLS are critical for the prevention of irreversible organ damage. Although TLS does not present with specific clinical symptoms, this case highlights the importance of close monitoring through blood tests even after the initiation of chemotherapy in patients with solid tumors who are at risk for TLS. Particularly in tumors with known risk factors for TLS, it is essential to perform blood tests by the third day after the initiation of chemotherapy to assess for the development of TLS.