30th December 2024

Malignant superior vena cava obstruction (SVCO)

Overview of malignant SVCO

Superior vena cava obstruction is a medical emergency. Obstruction of venous delivery to the right atrium can cause increased venous pressures and reduced venous return from the head, neck and arms. This can result in life-threatening complications including laryngeal oedema or tracheal compression causing airway obstruction and cerebral oedema causing raised intracranial pressure.

It is, therefore, essential to recognise SVCO and any complications to allow immediate treatment (if life-threatening features) and further investigation.

Aetiology of SVCO

SVCO is predominantly caused by malignancy and its complications. Obstruction can be external, related to tumour mass or mediastinal lymphadenopathy, or secondary to thrombus. The causes of cancer related SVCO are summarised in Table 11.

External compression

The commonest cause of external compression is lung cancer. Non-small cell lung cancer (NSCLC) causes 50% of all SVCO, although less than 2% of patients with NSLC develop SVCO. Conversely, 15-20% of small cell lung cancer (SCLC) patients develop SVCO, however these only make up 25% of all SVCO cases, due to its lower prevalence.

Other malignancies that result in SVCO include non-Hodgkin’s lymphoma (usually driven by mediastinal lymphadenopathy) and, more rarely, thymomas or mediastinal germ cell tumours.

Superior vena cava (SVC) clots

Clots within the superior vena cava may also cause SVCO. Malignancy increases this risk due to its prothrombotic nature. Tumours that cause extrinsic compression of the SVC create turbulent flow, leading to thrombus formation. Patients receiving systemic anti-cancer therapy may have an indwelling intravascular device, such as Hickmann or PICC lines, which also increase risk of clotting.

Clinical features of SVCO

The signs and symptoms of SVCO (Table 12) are related to the back pressure in veins draining into the SVC.

Symptoms of SVCO

Patients may describe facial swelling and redness that may be worse in the mornings and when bending forward (due to poor venous return from the head and neck) and may improve on standing/sitting up due to gravity. These symptoms may be associated with a sense of pressure or discomfort.

They may have noticed progressive venous distension, or new veins, in their head, neck and upper chest.

The patient may have shortness of breath if there is associated laryngeal oedema or airway compression. There may be headache, nausea and, in some cases, confusion related to cerebral oedema.

Of note, there may be a subacute presentation, and patients may have noticed improvement in symptoms after a period of 2-3 weeks – once venous collaterals have been recruited.

Signs of SVCO

The patient may be plethoric in the head, neck and upper chest with or without associated oedema and distended veins. If there is laryngeal or bronchial oedema, stridor may be heard and the patient may be visibly dyspnoeic or cyanosed. If cerebral oedema has developed, papilloedema may be present.

Classically, there is a positive Pemberton’s sign: on holding both arms above their head for 2 minutes there is worsening plethora, venous distension, cyanosis and/or respiratory distress.

Investigations in SVCO

Eighty percent of patients with SVCO have an abnormal CXR. Findings include mediastinal widening (right-sided paratracheal mass or mediastinal lymphadenopathy) or other features of lung cancer, e.g. unilateral effusion.

CT thorax with contrast is important to delineate the cause and may also help evaluate underlying malignancy. If no mass is identified, a venogram will identify any thrombus and allow planning for thrombolysis or stent insertion.

Up to 50-60% of patients presenting with malignant SVCO do not have a prior diagnosis of cancer. In these cases, urgent investigations will need to be completed to diagnose the primary cancer (further imaging and biopsy).

Management of SVCO

In most cases of SVCO there is time to organise a tissue biopsy prior to definitive treatment, however if there is evidence of respiratory compromise or raised intracranial pressure, definitive treatment must not be delayed.

Emergency management of SVCO

If there are features of respiratory compromise (stridor, desaturation or dyspnoea), then initially:

1. Sit patient upright or elevate head and neck; deliver 100% FiO2 (fraction of inspired oxygen); establish IV access
2. Start high-dose corticosteroids to reduce perilesional oedema (16 mg dexamethasone stat then continue OD). There is little evidence that steroids are beneficial in most non-haematological causes of SVCO, however they continue to be prescribed due to relatively low side effect profile in short duration
3. Check arterial blood gas and monitor saturations; if in respiratory failure, involve ITU and ENT
4. An emergency tracheostomy may be required if severe airway compromise

Ongoing and definitive management of SVCO

Ongoing management requires full investigation as discussed above, followed by treatment to relieve the obstruction (Table 13). Generally, stenting is preferred as it relieves symptoms quickly, is very successful and can be re-attempted if symptoms recur.

References

• Cassidy J, Bissett D, Spence RAJ, Payne M, Morris-Stiff GJ. Oxford Handbook of Oncology. 4th ed. Oxford: Oxford University Press; 2015
• National Institute for Health and Clinical Excellence. Stent placement for vena caval obstruction [Internet]. NICE. 2004 [cited 2022 Apr 17]. Available from: https://www.nice.org.uk/guidance/ipg79
• Rowell NP, Gleeson FV. Steroids, Radiotherapy, Chemotherapy and Stents for Superior Vena Caval Obstruction in Carcinoma of the Bronchus: a Systematic Review. Clinical Oncology. 2002 Oct;14(5):338–51
• Drews RE, Rabkin DJ, Bruera E, Eidt JF, Mills, Sr JL, Muller NL, et al. UpToDate: Malignancy-related superior vena cava syndrome [Internet]. UpToDate. 2022 [cited 2022 Apr 17]. Available from: https://www.uptodate.com/contents/malignancy-related-superior-vena-cava-syndrome