RESUMEN
We report a case of an 83-year-old woman who developed tumor lysis syndrome (TLS) 5 days after FOLFIRI+cetuximab (Cmab) therapy. A huge ascending colon cancer measuring 10 cm in diameter and with peritoneal dissemination was diagnosed. Following successful therapy with FOLFIRI alone, FOLFIRI+Cmab was administered. On day 5, TLS was diagnosed with hyperuricemia, hyperkalemia, hyperphosphatemia, and an increase in serum creatinine. Intravenous furosemide, volume loading, and glucose-insulin therapy resulted in improvement of laboratory data in 2 days. However, she died on the 34th day due to multiple organ failure caused by aspiration pneumonia following small intestine functional ileus. Although TLS is a rare complication in colon cancer, its onset must be taken into consideration. Also, risk assessment and preventive therapy for TLS should be performed before cancer treatment.