ONCOLOGIC EMERGENCIESThey are defined as an acute, life-threatening events related to patient's neoplasm or its treatment, which may lead to death.
TYPES OF ONCOLOGIC EMERGENCIESThe various
oncologic emergencies are:
- Tumor lysis syndrome
- Superior vena cava syndrome
- Spinal cord compression
- Cardiac tamponade
- Neutropenic enterocolitis
Peripheral leucocyte more than 100,000/cu mm and increasing progressively is called hyperleucocytosis. It is seen predominantly in ALL and AML. In ALL, patients are prone to acute tumor lysis syndrome due to increased sensitivity of lymphoblasts to chemotherapy. In AML, it causes hyperviscosity and hemorrhage in the lungs and brain due to their rigidity and stickiness. Death is highly significant if the leukocyte count exceeds 300,000/cu mm.
- Hydration: Patients are hydrated rapidly with 5% Dextrose and 0.25% saline at 3000 ml/m2/24 hours with alkalinization of urine by administration of NaHCo3 35-45mEq/m2/24 hours.
- Allopurinol: 10mg/kg/day tds to prevent uric acid nephropathy.
- Cytoreduction with exchange transfusion & leukopheresis- is controversial.
* Red cell transfusion and diuretics should be avoided to prevent hyperviscosity
TUMOR LYSIS SYNDROMEIt is a triad of hyperuricemia, hyperkalemia and hyperphosphatemia (usually with hypocalcemia) due to rapid release of intracellular metabolites at rates exceeding the kidney's excretory capacity. It may occur before therapy or during the first few days after starting chemotherapy. Patient with bulky T-cell or B-cell leukemia or lymphomas (Burkitt's lymphoma) are at the greatest risk. It is very rare in AML and other solid tumors.
Prevention is the best treatment. Measures are directed towards decreasing uric acid production, increasing uric acid solubility and reducing the concentration of uric acid in urine.
- Hydration with diuretic therapy: Maintain a urine output of at least 100ml/m2/hour. So long as the urine output is maintained, hyperkalemia may not be fatal.
- Urine Alkalinization: Keep urine pH above 7.0. Alkalization should be stopped as soon as serum uric acid is 9mg/kg or less.
- Allopurinol: 10mg/kg /day for 7 days followed by 5mg/kg for another 7 days.
- Hypocalcemia should not be treated unless symptomatic.
SUPERIOR VENA CAVA SYNDROMESigns and symptoms seen with compression or obstruction to the vena cava are called superior venacava syndrome. Malignant tumors especially non-Hodgkin's lymphoma (NHL), ALL (T-cell) Hodgkin's disease, Neuroblastoma and Ewing's sarcoma are commonly associated with it. Cough, hoarseness, dysnoea, stridor along with facial puffiness, plethora, cyanosis (facial) and suffusion of conjunctiva are the primary features. Venous engorgement of the neck, chest and arm with collateral vessels may be seen. Symptoms are aggravated when patient is flexed as for lumbar puncture.
When malignancy is the usual cause of SVC obstruction, it is important to obtain a tissue diagnosis before initiating therapy. Because of risk of anesthesia in a patient with airway obstruction and poor venous return, the diagnosis should be attempted by least invasive means.
In situations, where tissue diagnosis is not possible without biopsy under general anesthesia, it is best to give empirical therapy. Radiotherapy is gold standard. It may be given alone or with steroids. Steroids reduce post-radiation edematous swelling of tumor and consequent additional tracheal compression. Improvement is seen within 12 hours of starting radiotherapy.
In patients with leukemia and lymphoma, chemotherapy is also effective.
* If patient does not improve in 3-4 days, urgent thoracotomy may be required.
SPINAL CORD COMPRESSIONLocal extension or metastasis of tumor to the spinal cord leads to spinal cord compression. It is seen commonly with Ewing's sarcoma, neuroblastoma, lymphoma, leukemia and osteogenic sarcoma. Back pains either local or radicular is the key symptom. Any child with malignancy and back pain should be considered to have spinal cord compression until proved otherwise. Neurological deficits may also occur. MRI or myelography is required for diagnosis.
Immediate dexamethasone is required. Local radiotherapy, surgical decompression and chemotherapy may be used singly or in combination.
CARDIAC TAMPONADECardiac tamponade is seen with pericardial effusion due to acute leukemia and Non-Hodgkin's lymphoma. It can also occur with tumors of heart muscle and pericardium. Diagnostic and therapeutic pericardiocentesis should be performed under fluoroscopic control. Malignant pericardial effusion due to hematological malignancies is best treated with systemic chemotherapy.
NEUTROPENIC ENTEROCOLITISNeutropenic enterocolitis is an acute, life threatening inflammation of the small and large bowel in children with malignancies during periods of prolonged or severe neutropenia. Supportive therapy with broad spectrum antibiotics, bowel rest and blood component therapy is required. Surgery is indicated for intestinal perforation, persistent gastrointestinal bleeding and uncontrolled sepsis. The prognosis is still very poor with mortality ranging from 50-100%.