Superior Vena Cava Syndrome Due to Malignancy

Superior vena cava (SVC) syndrome due to malignancy is obstruction of venous return from the head, neck and upper limbs through the SVC by external compression, direct invasion or thrombosis. It causes facial and arm swelling and breathlessness, and urgent treatment is needed only for airway or cerebral compromise; histological diagnosis before treatment is usually preferred.

It occurs in 3% to 15% of patients with lung cancer, and in lymphoma, thymoma and germ cell tumours. Malignancy causes 60% to 90% of cases: small cell lung cancer is the commonest cause, then non-small cell lung cancer, non-Hodgkin lymphoma and mediastinal metastases. Central venous catheters and pacing leads are the commonest benign causes.

Pathophysiology. The thin walled, low pressure SVC is easily compressed by enlarged paratracheal and right hilar nodes. Obstruction increases venous pressure, and collateral veins develop over weeks (azygos, internal mammary, lateral thoracic).

Prognosis. Survival depends on the underlying tumour (months for lung cancer, long term cure for lymphoma and germ cell tumours). SVC obstruction itself rarely causes death unless the airway or brain is affected.

• Facial and neck swelling (often worse in the morning or when bending), arm swelling, dyspnoea and cough.
• Distended neck and chest wall veins, facial plethora, conjunctival oedema, and Pemberton sign (facial congestion on raising the arms).
• Headache, dizziness and syncope (cerebral oedema), hoarseness and stridor (laryngeal oedema).

Red flags.

• Stridor or severe dyspnoea.
• Confusion, reduced consciousness or seizures.

• Contrast CT of the chest (venous phase) shows the level of obstruction, thrombus, collaterals and the cause. Venography for stent planning.
• Tissue diagnosis (bronchoscopy, CT-directed biopsy, mediastinoscopy, or biopsy of an accessible node) before radiotherapy or chemotherapy, because treatment may obscure histology, except in an emergency.
• FBC, LDH, tumour markers (AFP, beta-hCG for germ cell tumours), chest radiograph and staging.

Differential diagnosis.

• Benign causes: catheter related thrombosis, fibrosing mediastinitis, goitre
• Cardiac tamponade, constrictive pericarditis and heart failure
• Angioedema and cellulitis

General measures. Sit the patient upright, give oxygen, and avoid cannulation of the upper limbs when possible.

Endovascular stenting. For symptomatic patients with severe or life threatening symptoms (stridor, cerebral oedema), or those with a tumour poorly responsive to radiotherapy and chemotherapy. Symptoms improve in 24 to 72 hours in over 90%.

• Anticoagulation after stenting or in thrombotic obstruction: enoxaparin 1 mg/kg subcutaneously twice daily (or 1.5 mg/kg once daily) while the thrombotic risk persists, for at least 6 months and as long as active disease remains; maximum 1.5 mg/kg daily; monitoring: platelet count at baseline and every 2 to 4 weeks for the first month, creatinine, signs of intracranial haemorrhage, anti-Xa level in obesity or renal impairment; adjustment: 1 mg/kg once daily when creatinine clearance is under 30 mL/min, hold for intracranial haemorrhage or platelets under 50 x 10^9/L, avoid in brain metastasis with recent bleeding
• Antiplatelet therapy after stent placement: aspirin 75 mg orally once daily for 3 to 6 months after stent placement; maximum 100 mg daily; monitoring: bleeding, FBC, gastric symptoms; adjustment: stop for platelets under 50 x 10^9/L or active bleeding, add gastric protection in patients with ulcer risk, avoid combining with other antiplatelet drugs unless prescribed by the interventional team

Corticosteroids. For lymphoma, thymoma or radiotherapy related oedema.

Dexamethasone 4 mg orally or IV once or twice daily for mild symptoms and up to 4 mg four times daily for marked oedema or raised intracranial pressure, for the shortest period, tapered over 1 to 2 weeks once symptoms settle; maximum 16 mg daily.

Monitoring: glucose, blood pressure, mood and sleep, gastric symptoms (gastric protection when combined with other risk factors), opportunistic infection, myopathy.

Adjustment: use the lowest effective dose, avoid prolonged courses because of myopathy, osteoporosis and infection, use lower doses in hepatic impairment.

Cancer treatment.

• Small cell lung cancer, lymphoma and germ cell tumours: chemotherapy (and rituximab for lymphoma) gives rapid relief, with response in days.
• Non-small cell lung cancer and other radioresistant tumours: radiotherapy (for example 30 Gy in 10 fractions or 8 Gy in 1 to 2 fractions) or stenting, with systemic therapy by molecular profile.
• Catheter related thrombosis: anticoagulation and catheter removal if no longer needed.

Monitoring. Daily clinical review of oedema, airway and neurology while symptomatic. CT after treatment to assess response. Stent patency review (symptoms of recurrence) every 3 months.

Referral and escalation.

• Same day oncology or interventional radiology referral for symptomatic SVC obstruction.
• Emergency anaesthetic and airway review for stridor.

Special groups.

• Children: more rapid airway compromise because of a compressible trachea, and lymphoma needs urgent diagnosis before general anaesthesia.
• Anticoagulated patients: monitor bleeding risk and platelets.
• Pregnancy: radiotherapy and contrast imaging only if needed, with fetal shielding.