The superior vena cava (SVC) is a large vein that carries blood from the body straight to the heart. It lies in the middle of the chest, behind the breast bone (sternum).

Superior vena cava obstruction (SVCO) occurs when something blocks the blood from flowing along the SVC. The walls of the SVC are thin, meaning they easily become squashed (compressed).

Most cases of SVCO are caused by an underlying lung cancer. The cancer itself may be pressing on the SVC, or secondary tumours from the cancer may have swollen and enlarged the lymph nodes.

Other possible causes are:

• Other cancers affecting the lymph nodes in the chest. Lymphomas, testicular cancer and breast cancer are sometimes associated with SVCO in this way.
• A blood clot forming in the vein and obstructing the blood flow. This can result from treatment with a central line (a small plastic tube, threaded into the vein to give treatments like chemotherapy).
• Illnesses other than cancer (benign conditions), although this is uncommon.

SVCO often develops quite rapidly over a few weeks, or even days. Occasionally it develops more slowly; this is more likely when it is caused by a benign (non-cancerous) condition.

Symptoms are caused by the blood flow to the heart being obstructed. The first symptom is often a sensation of fullness in the face when you bend over. The most common symptoms include:

• breathlessness, due to swelling around the windpipe (trachea)
• headaches, which worsen on leaning forward or bending over
• facial swelling with a dark red look to the complexion
• swollen neck
• swollen arms and hands
• visible swollen blue veins on the chest
• dizziness.

Chest X-ray This is the most common test for SVCO. Occasionally other tests such as a CT or MRI scan may be needed.

If someone is diagnosed with SVCO but is not known to have cancer, tests will be done to establish the cause.

Although symptoms can be severe and distressing, they can be quickly controlled by treatments:

Bed rest Your doctor will usually advise bed rest, ideally with the head of the bed raised. If you are short of breath, sitting in an upright position might be more comfortable. You may also need an oxygen supply.

Steroids High doses of a steroid called dexamethasone (decks-a-meth-a-zone) will usually be given to help reduce pressure and swelling around the blood vessel, and improve symptoms including breathlessness. The amount you are given will be reduced gradually after other treatments like radiotherapy or chemotherapy have started, depending on how quickly symptoms improve.

Radiotherapy Radiotherapy uses high‑energy rays to destroy cancer cells. It is usually used alone, but can be used in combination with other treatments, like chemotherapy. Radiotherapy rays are directed at the tumour from outside the body – this is known as external radiotherapy. Radiotherapy is given as a short course and usually starts immediately after SVCO is diagnosed.

Stent A stent is a small tube which can be inserted into the blood vessel to keep it open, allowing the blood to flow through. This treatment is done under a general anaesthetic. The doctor uses x-ray images to guide the stent into the right position. It can be used if doctors feel that radiotherapy or chemotherapy is unlikely to help, or if the SVCO has come back after radiotherapy or chemotherapy. It relieves most people’s symptoms within 72 hours. This treatment is not suitable for people who have a blood clot, and because it requires a tube to be inserted into the main vein in the chest, not everyone will be fit enough to cope with it.

Chemotherapy Chemotherapy uses anticancer (cytotoxic) drugs to destroy cancer cells. It is occasionally used to treat SVCO due to tumours that are sensitive to chemotherapy, such as lymphoma or small cell lung cancer. Chemotherapy can also be used to treat SVCO in breast cancer.

Drugs to thin the blood Drugs known as anti-coagulants, like heparin and warfarin, dissolve clots and can therefore be used to treat SVCO that has been caused by a blood clot. If the blood clot is around a central line, it may be necessary to remove the line.

Superior vena cava obstruction can be very frightening as it often involves swelling, feelings of breathlessness, and choking. You may have many different emotions, including anxiety and fear. These are normal reactions and are part of the process many people go through in trying to come to terms with their condition.

Everybody has their own way of coping with difficult situations; some people find it helpful to talk to friends or family, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is available if you need it.

This section is based upon our superior vena cava obstruction factsheet which has been compiled using information from a number of reliable sources, including:

• Doyle et al. Oxford Textbook of Palliative Care. 3rd Edn. Oxford University Press. Oxford, England, 2005.
• Faull et al. Handbook of Palliative Care. 2nd Edn. Blackwell Publishing, 2005.
• Kallab, A et al. Superior Vena Cava Syndrome. www.emedicine.com. Accessed February 2006.

For further references, please see the general bibliography.