One or both legs can become swollen after pelvic radiotherapy but this is uncommon.

The swelling is due to a build up of lymph fluid. This happens if the lymph nodes (or glands) in the groin or pelvic area have been removed during surgery or if they have become damaged by radiotherapy. Lymphoedema can occur a few weeks or several years after pelvic radiotherapy. It happens in up to 1 in 10 people (10%). The risk of it happening to you depends on the type of cancer you had, as well as any other treatments you had. Rarely, the trunk or genital area can become swollen.

The lymph nodes act as filters within the lymphatic system, helping to fight infection and disease. If the nodes have been removed or are damaged, the lymph fluid is unable to pass along the vessels and excess fluid can build up, causing swelling. The area affected by lymphoedema is also more prone to infection and if infection happens it can be difficult to get rid of it.

Lymphoedema can also occur if the cancer has come back and is blocking lymph drainage channels.

If your leg is swollen because of lymphoedema it may become stiff, uncomfortable and awkward to move. This can make daily activities like dressing difficult. The skin may get tight and stretched. Once lymphoedema has occurred it cannot be completely cured.

However, many things can be done to help reduce the swelling and discomfort.

After pelvic radiotherapy it is important to avoid any infection of your legs, as this increases the risk of lymphoedema. It is important to avoid any cuts or grazes on your legs and to look after the skin by using moisturisers if the skin gets dry. Clean any cuts, grazes or wounds with antiseptic.

Some things may trigger lymphoedema, such as:

• insect bites
• standing for long periods
• air travel
• sunburn
• being overweight

It is helpful to avoid these if possible. You can help to prevent lymphoedema by following a healthy lifestyle and exercising regularly. Walking (in well-fitting shoes) and swimming stimulate fluid to drain from the legs.

The earlier treatment is started, the more likely the lymphoedema can be controlled. So it is important to let your doctor know if you notice any swelling of your foot, leg, thigh, lower abdomen or genital area.

If you develop lymphoedema you should be referred to a lymphoedema specialist for treatment and advice. The specialist may be a nurse, physiotherapist or doctor. The treatment you will need will depend upon how much lymphoedema you have. The treatment is given to help reduce the swelling, prevent further swelling and to relieve any discomfort. There are four main types of treatment:

• skin care (with moisturisers)
• using compression stockings or bandages
• positioning and movement of the leg
• a particular type of massage called manual lymphatic drainage (MLD) or self-massage lymphatic drainage (SLD).

If the area affected by lymphoedema gets infected you may have a temperature or flu-like symptoms, with a blotchy rash, pain in the area or increased swelling. Let your doctor know if this happens as you will need treatment with antibiotics.