Superior vena cava obstruction (SVCO)

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

Superior vena cava obstruction (SVCO) happens when something blocks the blood flow along the SVC. The walls of the SVC are thin and can easily become squashed or compressed.

SVCO is sometimes called superior vena cava syndrome.

Symptoms of SVCO are caused by the blood flow to the heart being blocked. This causes increased pressure in the head, neck and arms.

Symptoms can develop quickly over a few days or over a few weeks.

The most common symptoms are:

• breathlessness, because of swelling around the windpipe (trachea)
• headaches or feelings of fullness in the head, which get worse when you lean forward or bend over
• facial swelling, with changes to your natural skin colour and appearance (complexion)
• changes in your eyesight
• a swollen neck
• swollen arms and hands
• visible swollen veins on the chest
• feeling dizzy.

If you have any of these symptoms it is important to contact your cancer doctor or nurse straight away. SVCO needs to be treated quickly.

The symptoms of SVCO can be distressing, but they can usually be quickly controlled.

You may be given oxygen to improve your breathing. You may also have drugs such as:

• painkillers, to ease any pain
• water tablets (diuretics) to get rid of extra fluid
• sedatives, to help you relax.

Your doctor may give you high doses of a steroid drug called dexamethasone. This will help reduce pressure and swelling around the blood vessel. It will also improve symptoms such as breathlessness. The dose will be reduced gradually after you have had other treatments.

Your doctor will usually advise bed rest, with the head of the bed raised. If you are breathless, sitting in an upright position might be more comfortable.

There are different ways of treating SVCO. The treatment you have will depend on how severe the symptoms are and the type of cancer you have.

A stent is a small tube that can be put into the SVC to keep it open. This lets the blood flow through. Not everyone will be able to have this treatment. For example, a stent may not be suitable for people who have a blood clot. Your doctor can tell you if it is the best option for you.

A doctor called a radiologist will usually put the stent in using local anaesthetic so you do not feel anything in the area being treated. They may also give you medicine to help you relax. They pass a narrow tube called a catheter up through a blood vessel, for example at the top of the leg. They pass the stent through the catheter using x-ray images to guide it to the blockage in the vena cava.

You may have a stent as the first treatment for SVCO. It relieves symptoms quickly. You may also have a stent if SVCO comes back after having radiotherapy or chemotherapy.

Radiotherapy uses high-energy x-rays to destroy cancer cells, while doing as little harm as possible to normal cells.

Radiotherapy is directed at the tumour from outside the body. This is called external radiotherapy. You might have a short course of radiotherapy to reduce the area of cancer, causing pressure on the vein.

Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. It is sometimes used to treat SVCO where the tumours are sensitive to chemotherapy, for example with lymphoma or small cell lung cancer (SCLC).

Drugs called anti-coagulants can be used to treat SVCO caused by blood clots. These drugs help to prevent blood clots from forming. There are different drugs that can be used. If the blood clot is around a central line you may need to have the line removed. In this situation, your doctors will discuss other cancer treatment options with you.