Metabolic emergencies represent rare events in the care of cancer patients. In contrast to the measured pace of most of oncology, these scenarios demand prompt identification and intervention. This chapter reviews tumor lysis syndrome, hyponatremia, and hypercalcemia.
Tumor lysis syndrome is a collection of metabolic derangements secondary to the release of tumor cell contents into the extracellular space (Table 20-1). The rapid development of hyperphosphatemia, hyperuricemia, and hyperkalemia can cause devastating renal and cardiac complications. Hypocalcemia occurs secondarily as a consequence of hyperphosphatemia.
TABLE 20-1FEATURES OF TUMOR LYSIS SYNDROME
Tumor lysis syndrome occurs most frequently in rapidly growing hematologic malignancies such as acute leukemias and Burkitt's lymphoma. In these diseases, it can occur either spontaneously or more commonly 6–72 h following initiation of antitumor therapy. There are case reports of even more rapid onset with the use of targeted therapies. The syndrome is most frequently associated with cytoxic chemotherapy but can occur after embolization, radiation, or glucocorticoids. The Cairo-Bishop definitions and grading system for laboratory and clinical tumor lysis syndrome are not widely used in clinical practice (Table 20-2) (1). The National Cancer Institute Common Toxicity Criteria 4.0 system grade TLS by its presence (grade 3), life threatening consequences (grade 4), or death (grade 5).
TABLE 20-2CAIRO AND BISHOP DEFINITION AND GRADING CLASSIFICATION OF TUMOR LYSIS SYNDROME ||Download (.pdf) TABLE 20-2 CAIRO AND BISHOP DEFINITION AND GRADING CLASSIFICATION OF TUMOR LYSIS SYNDROME
| ||Laboratory TLS* ||Grade 0 ||Grade I ||Grade II ||Grade III ||Grade IV ||Grade V |
|Uric acid ||≥476 mmol/l or 25% IFB ||LTLS – ||LTLS + ||LTLS + ||LTLS + ||LTLS + ||LTLS + |
|Potassium ||≥6.0 mmol/l or 25% IFB || || || || || || |
|Phosphorous ||≥2.1 mmol/l in children or ≥1.45 mmol/l in adults or 25% IFB || || || || || || |
|Calcium ||≤1.75 mmol/l or 25% DFB || || || || || || |
|Creatinine ||Not defined ||≤1.5 ULN ||1.5 × ULN ||>1.5–3.0 × ULN ||>3.0–6.0 × ULN ||>6.0 × ULN ||Death |
|Cardiac arrhythmia/ sudden death ||None ||None ||No intervention indicated ||Nonurgent intervention indicated ||Symptomatic and incompletely or device controlled ||Life threatening ||Death |
|Seizure ||None ||None ||None ||One seizure or well controlled by anticonvulsants or infrequent focal motor seizures not interfering with ADL ||Seizure with altered consciousness, poorly controlled or generalized seizure despite intervention ||Prolonged, repetitive, or difficult to control seizures ||Death |