Most oncologic emergencies can be classified as metabolic, hematologic, structural, or side effects from chemotherapy agents. Tumor lysis syndrome is a metabolic emergency that presents as severe electrolyte abnormalities. The condition is treated with allopurinol or urate oxidase to lower uric acid levels. Hypercalcemia of malignancy is treated with aggressive rehydration, furosemide, and intravenous bisphosphonates. Syndrome of inappropriate antidiuretic hormone should be suspected if a patient with cancer presents with normovolemic hyponatremia. This metabolic condition usually is treated with fluid restriction and furosemide. Febrile neutropenia is a hematologic emergency that usually requires inpatient therapy with broad-spectrum antibiotics, although outpatient therapy may be appropriate for low-risk patients. Hyperviscosity syndrome usually is associated with Waldenstrom’s macroglobulinemia, which is treated with plasmapheresis and chemotherapy. Structural oncologic emergencies are caused by direct compression of nontumor structures or by metastatic disease. Superior vena cava syndrome presents as neck or facial swelling and development of collateral venous circulation. Treatment options include chemotherapy, radiation, and intravenous stenting. Epidural spinal cord compression can be treated with dexamethasone, radiation, or surgery. Malignant pericardial effusion, which often is undiagnosed in cancer patients, can be treated with pericardiocentesis or a pericardial window procedure.
Related Results
How effective is prophylactic therapy for gout in people with prior attacks?
role of allopurinol in experimental acute necrotizing pancreatitis, The
Desensitization found effective for allopurinol.(Rheumatology)(Brief Article)
Cardiome Acquires Clinical Program; Gout Program Builds on Congestive Heart F…
Interpharm Announces Revenue and Earnings for the Three-Month Period Ended Se…
**********
Family physicians are more likely to encounter emergencies related to the treatment or presence of cancer because of increases in outpatient cancer treatments and improved survival rates. Physicians should be familiar with these oncologic emergencies because treatment often is necessary before consultation with a subspecialist. (1) Some oncologic emergencies are insidious and take months to develop, whereas others manifest over hours, causing devastating outcomes such as paralysis and death. (2) In many patients, cancer is not diagnosed until a related condition emerges. Various clinical syndromes often are evident before an emergency occurs; therefore, a patient-focused approach that includes education and cancer-specific monitoring is needed. (3) Most oncologic emergencies (Table 1 (1,2,4-12)) can be categorized as metabolic, hematologic, structural, or side effects from chemotherapy agents. (4)
Metabolic
Metabolic emergencies include tumor lysis syndrome, hypercalcemia of malignancy, and syndrome of inappropriate antidiuretic hormone (SIADH).
TUMOR LYSIS SYNDROME
Tumor lysis syndrome is acute cell lysis caused by chemotherapy and radiation therapy. The release of intracellular products (e.g., uric acid, phosphates, calcium, potassium) overwhelms the body’s homeostasis mechanisms. (5) Tumor lysis syndrome is more common with hematologic malignancies or cancers with rapidly growing tumors, particularly acute leukemias and high-grade lymphomas. Tumor lysis syndrome usually presents within one to five days of chemotherapy or radiation. (6)
Patients with tumor lysis syndrome commonly present with azotemia, acidosis, hyperphosphatemia, hyperkalemia, hypocalcemia, and acute renal failure. (13) Treatment includes inpatient monitoring, vigorous fluid resuscitation, allopurinol (Zyloprim) or urate oxidase (uricase) therapy to lower uric acid levels, urinary alkalinization, and hemodialysis. (1)
HYPERCALCEMIA OF MALIGNANCY
Hypercalcemia of malignancy occurs in 20 to 30 percent of patients with cancer. (14) This condition most commonly is associated with multiple myeloma and cancers of the lung, breast, and kidney. Mechanisms that are thought to be important in the development of hypercalcemia of malignancy include bone-resorbing cytokines; parathyroid hormone-related peptide, secreted by the tumor, that binds to parathyroid hormone receptors; tumor-mediated calcitriol production; and, occasionally, ectopic parathyroid hormone secretion. (7,14)
Symptoms of this condition include nausea, vomiting, constipation, progressive decline in mental function, renal failure, and coma. (14,15) Occasionally, serum calcium levels are 14 mg per dL (3.50 mmol per L) or more. (16) Hypercalcemia of malignancy is associated with a poor prognosis, with more than 50 percent of patients dying within 30 days of diagnosis. (14) However, treating hypercalcemia of malignancy allows time for treatment of the underlying tumor. (14)
Treatment of hypercalcemia of malignancy (Table 2 (14,17)) includes aggressive rehydration followed by diuresis with furosemide (Lasix). Serum phosphorus should be monitored because hypophosphatemia is common and can worsen the condition. (14) Phosphorus should be replaced orally or via a nasogastric tube.8,14 Intravenous bisphosphonate therapy can inhibit osteoclastic bone resorption. Although pamidronate (Aredia) and zoledronic acid (Zometa) can effectively manage hypercalcemia of malignancy, a pooled analysis of two clinical trials showed that the more potent zoledronic acid is superior. (18) Zoledronic acid and pamidronate have been shown to improve quality of life in patients with metastatic bone disease by reducing skeletal complications, bone pain, and the need for analgesic medications. (19,20) Adjunctive treatments include dialysis and glucocorticoid, calcitonin (Miacalcin), plicamycin (Mithracin), and gallium nitrate (Ganite) therapies. (14)