emDOCs Podcast – Episode 42: Oncologic Emergencies Part 1
- Nov 23rd, 2021
- Brit Long
Today on the emDOCs cast with Brit Long, MD (@long_brit), we cover several oncologic emergencies, including SVC syndrome, malignant pericardial effusion, malignant spinal cord compression, and hypercalcemia.
Episode 42: Oncologic Emergencies Part 1
Superior vena cava (SVC) syndrome
– Occurs due to obstruction of blood through the SVC, caused by internal vascular invasion or external compression.
– Malignancy such as lung cancer is most common (60%); intravascular catheters account for 40% of presentations. Malignancy is the predominant cause, commonly non-small cell and small cell lung cancer, followed by lymphoma. Thrombosis of the SVC accounts for the majority of nonmalignant causes of SVC syndrome, usually a result of an indwelling intravascular device. Post-radiation fibrosis and fibrosing mediastinitis are other causes.
– The time of symptom onset depends on the rate of obstruction and venous collateral formation.
– Dyspnea is the most common symptom, with patients also complaining of face fullness/swelling. Cough, chest pain, and dysphagia are other symptoms. Unfortunately if rapid onset of symptoms occurs and no collateral flow is present, rapid onset of airway edema may present necessitating intubation.
– Facial edema and distension of neck and chest wall veins are commonly seen, though facial plethora and arm edema are rare. Usually symptoms are gradual over weeks with increase in venous pressure, and then improve with collateral vessel formation.
– Chest xray is abnormal in 84% of patients, often showing widening of the mediastinum and pleural effusion. The optimal imaging is CT of the chest with contrast, which shows venous drainage, point of blockage, and identifies the cause of obstruction. Collateral vessel presence on CT has a specificity of 96% and sensitivity of 92%. MRV, US, and cavogram are other imaging options. Biopsies are often taken of the mass if cancer is found.
– Treatment involves symptom relief and disease management. If a malignancy is chemotherapy sensitive, systemic chemotherapy is warranted. A stent can be placed by interventional radiology for severe symptoms. Radiotherapy is done for non-small cell lung cancer following stent placement. If thrombus is present, systemic anticoagulation with heparin is needed. If airway edema is present, emergent stenting with radiation is necessary, with high-dose steroids. Though classically included in the treatment in boards review, diuretics are not supported in the literature.
– Survival is 6 months on average once the diagnosis is made.
Malignant pericardial disease
– Present in up to one third of cancer patients and is most commonly due to metastases from lung or breast cancer. The majority of pericardial effusions (90%) are not malignancy-related.
– Most patients will present with exertional dyspnea (80%). A slow accumulation of fluid can allow up to 2L in the pericardial sac to collect with no change in hemodynamics. The acute accumulation of fluid causes decompensation.
– Ultrasound is the key to diagnosis and allows evaluation for tamponade (right atrial collapse in late diastole and right ventricular collapse in early diastole).
– Pericardiocentesis is often the necessary treatment, with ultrasound guidance preferred.
– Unfortunately up to 60% of patients will have recurrent pericardial effusions after drainage. Median survival is 2-4 months.
Malignant spinal cord compression
– Common cancer complication resulting from thecal sac compression, usually from local disease progression from vertebral body metastases from lung, kidney, breast cancer, or multiple myeloma.
– 3 types of compression: intramedullary (metastasis in the dura mater), leptomeningeal (metastasis on top of the dura mater), and external compression (90% of cases).
– The thoracic spine has the most blood supply and greatest number of vertebrae (60-70% of cases). It also possesses the least amount of space in the spinal canal.
– Back pain is the most common complaint found in 80-95% of patients, which often precedes other symptoms by two months. Half of patients will have bowel/bladder dysfunction at presentation, so obtaining a post-void residual or ultrasound can be helpful in the evaluation.
– The most important aspect is diagnosis; the best prognostic factor is pretreatment ambulation and neurologic status.
– MRI of the whole spine is needed for adequate visualization; 1/3 of patients will have multiple sites of metastasis and/or compression.
– Pain management is the first item of treatment, with opiate analgesics and glucocorticoids both supported by literature.
– Definitive treatment involves surgery, external beam radiotherapy, or stereotactic body radiotherapy. If the spine is unstable, surgery is usually needed.
– Median survival is 6 months.
– Hypercalcemia of malignancy occurs in 20 to 30% of cancers and is due to three different mechanisms: parathyroid-related protein (PTHrP) production seen in squamous cell carcinoma and lymphoma (80%), osteoclast activating factor seen in multiple myeloma or metastases causing osteolysis (20%), and endogenous calcitriol (1,25-dihydroxyvitamin D) production seen in lymphomas (<1%).
– The most common cancers with bone involvement are breast and lung cancer and multiple myeloma.
– Presentation: dehydration, polydipsia, fatigue, confusion, nausea/vomiting, constipation, decreased urine output, and ECG changes (bradycardia, prolonged PR, widened QRS, short QT).
– Management includes obtaining an ionized calcium and electrolyte panel with ECG. Patients with mild hypercalcemia (<12mg/dL) with no symptoms do not need immediate treatment, but need adequate fluid intake. Mild symptoms with levels of 12-14mg/dL is often chronic, and treatment should be aimed at rehydration and finding the cause.
– Severe hypercalcemia is defined by levels > 14mg/dL with severe symptoms. Initial treatment is with crystalloids, crystalloids, and more crystalloids at 200-300ml/hr. Loop diuretics are not recommended in the absence of renal or heart failure because of potential complications. Calcitonin is the fastest acting medication, given at 4 international units/kg IM or subcutaneously (tachyphylaxis is common after 1st dose). Bisphosphonates such as pamidronic acid (60-90mg IV over 2 hours) and zoledronic acid (4mg IV over 15 minutes) are mainstays of therapy. Hydration and calcitonin will lower levels by 12 hours, with bisphosphonates working within 24 to 72 hours. Admission is recommended. If neurologic deficits are found with a level of 18mg/dL or greater, dialysis is warranted. Glucocorticoids are only warranted if mechanism of hypercalcemia is due to calcitriol overproduction.