Tumor lysis syndrome (TLS) is a potentially life-threatening medical emergency that occurs when large numbers of cancer cells die rapidly—usually within hours to days of starting chemotherapy or targeted cancer treatments.

Tumor lysis syndrome (TLS) is a potentially life-threatening medical emergency that occurs when large numbers of cancer cells die rapidly—usually within hours to days of starting chemotherapy or targeted cancer treatments. These dying cells flood the bloodstream with toxic levels of potassium, phosphate, and uric acid, which can cause kidney failure and cardiac arrest.