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

Radiotherapy is an important part of the treatment for soft tissue sarcomas, particularly those affecting the arms or legs. It is usually given after surgery to destroy any remaining cancer cells. Sometimes radiotherapy may be given before an operation (neo-adjuvant radiotherapy), either to shrink the tumour and make it easier for the surgeon to remove it successfully, or to avoid having to amputate the limb. If the radiotherapy is given after surgery, the wound from the operation must be healed before radiotherapy treatment is started.

Radiotherapy is sometimes given on its own and may be the only treatment needed. Radiotherapy is also given to relieve symptoms and control sarcomas that can’t be removed.

Radiotherapy for sarcomas is normally given as a series of short daily treatments in the hospital radiotherapy department. High-energy x-rays are directed from a machine at the area of the cancer. The treatments are usually given from Monday to Friday, with a rest at the weekend. The number of treatments will depend on the type, size and position of the cancer within your body, but the whole course of treatment for early cancer will usually last a few weeks. Each treatment takes about 10–15 minutes. Your doctor will discuss the treatment and possible side effects with you.

To make sure that the radiotherapy is as effective as possible, it has to be planned carefully. If your sarcoma is in an arm or a leg, you may have a plastic mould made. The mould helps to keep you still during radiotherapy treatment sessions and is fitted over the affected part of your body. It is made in the mould room, on your first few visits to the radiotherapy department.

You will also be asked to lie under a large machine called a simulator, which takes x-rays or CT scans of the area to be treated. Sometimes a CT scanner can be used for the same purpose. Treatment planning is an essential element of radiotherapy and it may take a few visits. The planning sessions during your first few visits will take longer than the actual radiotherapy treatment sessions.

Marks may be drawn on your skin to help the radiographer, who gives you your treatment, to position you accurately and to show where to direct the rays. These marks must stay visible throughout your treatment but they can be washed off once the course of treatment is over. Sometimes small permanent marks (like tattoos) may be made on your skin. At the beginning of your treatment, you will be given instructions on how to look after your skin in the area being treated, as radiotherapy can make the skin sore.

Before each session of radiotherapy, the radiographer will position you carefully on the couch and make sure that you are comfortable. During your treatment, which only takes a few minutes, you will be left alone in the room, but you will be able to talk to the radiographer who will be watching you carefully.

Radiotherapy is not painful, but you do have to lie still for a few minutes while your treatment is being given. The treatment will not make you radioactive and it is perfectly safe for you to be with other people, including children, after your treatment.

Radiotherapy can cause general side effects such as feeling sick and tiredness. The side effects you get will depend on the area of the body being treated and the length of your treatment. The clinical oncologist and radiographer will advise you what to expect.

Hair loss

Hair will only fall out in the area being treated by radiotherapy, so the treatment for soft tissue sarcomas will not make the hair on your head fall out. The hair that is lost may grow back after the treatment has ended, but is often lost permanently.

Skin care

During radiotherapy, the skin in the treated area may become darker or red and sore. Your radiotherapist will give you advice about skin care at the start of your treatment. Your doctor can prescribe a special cream to soothe sore skin if necessary.

Tiredness and fatigue

As radiotherapy can make you tired, try to get as much rest as you can, especially if you have to travel a long way for treatment each day.

Feeling sick

If nausea and vomiting occur they can usually be effectively treated with anti-sickness drugs (called anti-emetics), which your doctor can prescribe. If you don’t feel like eating, you can replace meals with nutritious, high-calorie drinks which are available from most chemists and can be prescribed by your GP. Our section on diet has some helpful hints on how to eat well.

All these side effects should disappear gradually once the course of treatment is over, but it is important to let your doctor know if they continue.

Long-term side effects

After radiotherapy, some people may develop swelling known as lymphoedema. This happens because the lymph glands and vessels can become damaged by the radiotherapy. Lymph fluid (which circulates around the lymphatic system) is unable to pass along the vessels and builds up, causing swelling.

If lymphoedema develops it can’t be cured, but it can often be treated and managed. To help prevent lymphoedema you should try to avoid getting any infection or inflammation in the area that has been treated with radiotherapy. You should try to avoid cuts or grazes in the area and help to look after your skin by using moisturisers if it gets dry.

Radiotherapy to a joint, such as the knee or elbow, may cause it to become stiff. To help prevent stiffness, it is important to keep the joint mobile by using it and doing regular exercise.

Our section on radiotherapy gives more detail about this treatment and side effects.