Oncologic emergencies

Last updated: September 11, 2023

Summarytoggle arrow icon

Oncologic emergencies are a group of potentially life-threatening conditions that can manifest as a result of malignant disease and/or their treatment. These conditions include, but are not limited to, leukostasis, tumor lysis syndrome (TLS), superior vena cava (SVC) syndrome, malignant hypercalcemia, and neutropenic fever. Symptomatic patients must be rapidly assessed with early specialist intervention. Therapeutic goals in the treatment of the underlying oncologic condition (e.g., palliative care) should always be taken into account during management. TLS results from rapid destruction of tumor cells releasing intracellular components into the bloodstream that can damage the kidneys and cause potentially fatal electrolyte imbalances. Management of TLS consists of hydration, correction of electrolyte disturbances and reduction of serum uric acid to preserve kidney function. Leukostasis results from massive amounts of leukocytes that cause microcirculatory obstruction leading to organ ischemia and failure. Management of leukostasis consists of cytoreduction, hydration, and prophylaxis against TLS. SVC syndrome results from impaired blood flow from the SVC into the heart, which leads to venous congestion in the head and upper extremities. Management of SVC syndrome depends on the underlying etiology and is aimed at reducing symptoms (e.g., fluid restriction), treating complications (e.g., cerebral edema), and restoring blood flow pharmacologically, radiologically, or mechanically.

This article covers tumor lysis syndrome, leukostasis, and superior vena cava syndrome. Neutropenic fever and hypercalcemia are discussed in separate articles.

Tumor lysis syndrometoggle arrow icon

Definition [1][2]

A potentially life-threatening oncologic emergency; resulting from the rapid destruction of tumor cells, which leads to a massive release of intracellular components; , e.g., potassium (K+), phosphate (PO43-), and uric acid, that can damage the kidneys and cause renal failure.

Etiology [1][2]

  • TLS most commonly occurs after initiating cytotoxic treatment in patients with hematologic malignancies (e.g., ALL, AML, or NHL).
  • Can also manifest unrelated to therapy in patients with a very high tumor burden


Think of “PUKE calcium to remember the electrolytes affected in tumor lysis syndrome: Phosphorus, Uric acid, and potassium (K+) are Elevated; Calcium is decreased.

Clinical features [3]

Signs and symptoms are closely related to the degree of electrolyte abnormalities and acute kidney injury.

Electrolyte abnormalities in TLS can lead to seizures, cardiac arrhythmias, and sudden cardiac death. [1]

Diagnostics [1]

Consider TLS in any patient with hematological malignancies and hyperleukocytosis who have electrolyte imbalances, kidney failure, or recently initiated cytotoxic therapy.

Diagnostic criteria

Although there is no universally established classification of TLS, the Cairo-Bishop definition is widely used to help confirm the diagnosis and guide management. [2][4]

Cairo-Bishop definition of tumor lysis syndrome [3]
Laboratory TLS Clinical TLS
  • Presence of ≥ 2 of the following around the period of treatment initiation (including 3 days prior and 7 days after):
    • K+ > 6.0 mEq/L or 25% increase from baseline
    • PO43- > 4.5 mg/dL (1.45 mmol/L) or 25% increase from baseline
    • Uric acid > 8.0 mg/dL (476 micromol/L) or 25% increase from baseline
    • Corrected calcium < 7.0 mg/dL (1.75 mmol/L) or ionized Ca2+ < 4.5 mg/dL (1.12 mmol/L) or 25% decrease from baseline

Management of TLS [1][2][4][5]

Renal replacement therapy is indicated if the following complications are intractable: fluid overload, electrolyte imbalances, or hyperuricemia.

Fluid management

Hydration is the mainstay of TLS prophylaxis and treatment.

Hydration is the most effective preventive measure.

Avoid nephrotoxic drugs (e.g., NSAIDs) and fluids with added potassium due to the risk of hyperkalemia.

Electrolyte imbalances

Monitor electrolytes regularly, as they can be also be affected by fluid therapy.


Rasburicase is indicated for patients with established TLS or those at intermediate to high risk for TLS.

Acute management checklist for established TLS

Leukostasistoggle arrow icon

Definitions [8]

Etiology [8][9]


  • Very high number of leukemic blasts → increased viscosity of blood → increased risk of vascular obstruction → tissue hypoxemia and infarction clinical features of leukostasis
  • Contributing factors: endothelial activation and high metabolic activity of the dividing immature leukocytes [5]

Clinical features [5][9]

Clinical features depend on the affected system or organ. Although the lungs and the CNS are most commonly affected; , leukostasis can also cause TLS and DIC (a frequent complication of APL).

Diagnostics [5][9]

Laboratory studies [5][9]

Findings are nonspecific and vary widely depending on the organ system involved and the underlying condition.

Hyperleukocytosis can lead to falsely normal platelet counts, falsely reduced PaO2, and falsely elevated potassium levels.

Imaging and additional studies [9]

Additional diagnostics should be guided by clinical symptoms and pretest probability and should not unnecessarily delay treatment.

Leukostasis is a clinical diagnosis in leukemia patients with a markedly elevated WBC count and signs of end-organ damage (particularly the CNS and the lungs). [9]

Leukostasis is a medical emergency. Diagnostic studies should not delay treatment.

Treatment [9] [8]

General principles


Individualize cytoreductive treatment regimens and involve specialists early.

Additional measures

Acute management checklist for leukostasis

Superior vena cava syndrometoggle arrow icon

Definition [12]

Venous congestion of the head, neck, and upper extremities resulting from impaired venous flow through the superior vena cava (SVC) to the right atrium.

Etiology [13]

Conditions that obstruct the SVC intraluminally (e.g., neoplastic invasion, thrombosis) or due to extraluminal compression (e.g., Pancoast tumors, mediastinal masses). The etiology of SVC syndrome is the basis for its classification.

Clinical features [12][14][15]

Symptoms usually progress over weeks, but rapid deterioration causing emergency presentation can occur. Evaluate patients for signs of increased ICP.

Evaluate frequently for signs of laryngeal edema, hemodynamic instability, and ↑ ICP.

Diagnostics [13][14]

Management [13][20]

General principles

  • Patients with severe symptoms usually require emergency endovascular treatment. [5]
  • Definitive treatment depends on the underlying condition.
  • Specialists should be involved early to provide an individualized treatment strategy.

Patients with severe or life-threatening SVC syndrome require emergency treatment (e.g., invasive venography with stent placement).

Supportive measures [13][20]

Invasive treatment

  • Stent placement: for unstable patients or patients with severe symptoms, regardless of the underlying cause
  • Surgical bypass or SVC reconstruction: individual decision [15][17]

Medical treatment [13][14][21]

Radiotherapy and chemotherapy usually require prior histologic confirmation of the underlying malignancy.

Acute management checklist for SVC syndrome

Referencestoggle arrow icon

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