Side effects

Radiotherapy has side effects. Your clinical oncologist will have discussed these with you when they asked for your consent for treatment. You can speak to someone in your treatment team if you have any questions.

We cannot prevent side effects, but we can help you to manage them. We use the most modern radiotherapy techniques available to reduce the side effects as much as possible. However, some side effects are unavoidable. We will support you and help you to manage these side effects, with advice and medicines where necessary.

The treatment support radiographers will assess your reactions to treatment.

Possible early side effects

Side effects during your radiotherapy are called early, or acute, side effects. You might notice them any time during treatment. They are usually worse 1 to 2 weeks after your radiotherapy treatment ends. Then, they gradually start to improve. By 3 months after your treatment, most will have improved or gone. Early side effects are common, but they are different for everyone.

Skin reaction

Your skin might react to the radiation. It can become dry, itchy, and depending on your skin tone, red or darker. This may cause the skin to blister and the area to become moist (slightly wet). If this happens, the skin will fully heal after treatment has finished. The skin in the treatment area might stay darker for some time. This can sometimes be permanent.

Tiredness (fatigue)

You might feel tired and have a lack of energy. This will slowly get better once you have finished treatment.

Sore throat, pain or discomfort when swallowing

You might have a sore throat, or find it painful or uncomfortable when you swallow. If this happens, tell the radiographers. They will let the doctors know and you will be prescribed pain medicine. 

Possible long-term side effects

Side effects that happen months to years after the treatment are called long-term side effects. Not everyone has long-term side effects. They might start during treatment and then gradually get worse, or they might develop slowly, over a longer time. Some might improve slowly, but others might be permanent.

Breast swelling (oedema)

The breast might swell slightly during treatment. This might be permanent.

Fibrosis and shrinkage

After treatment, the breast might become firmer, and become smaller over a few months. This might be permanent.

Chest wall or breast tenderness

The area that has been treated might feel tender for several months after treatment.

Arm swelling (lymphoedema)

This might happen because of scar tissue, which might form after surgery, or radiotherapy, to the armpit. Your nurse can offer advice and treatment if this happens, but the changes are not usually permanent.

Effect on breast reconstruction

If you have had breast reconstructive surgery, such as an implant, radiotherapy might cause scar tissue, which may affect the result of the surgery. Your doctor will discuss this with you.

Uncommon long-term side effects

We try to reduce long-term side effects, and enhance the benefit from the treatment. All of these effects are very rare. Your doctor will discuss them with you in detail.

Stiff shoulder

The shoulder joint might become stiff after surgery or radiotherapy. Physiotherapy can help with this.

Rib pain

Radiotherapy can make rib bones brittle (weaker) after treatment. Very rarely, this might cause rib fracture. This can be painful but usually heals without treatment.

Lung reaction

A small area of the lung in the treatment area might become scarred. This might cause breathlessness. This is very rare, and happens in less than 1 in 100 patients.

Heart (cardiac) effects

Treatment to the left breast might involve treating a small area of the heart. In the past, this was associated with a small increase in the risk of heart disease (less than 1 in 100 patients). Modern radiotherapy planning lets us protect the heart to reduce the risk.

Telangiectasia (varicose veins)

Your blood vessels might become visible under the skin in the area that you had radiotherapy. If this happens, it usually takes many years to develop and is harmless.

Nerve complications

Very rarely, people might have pins and needles, numbness, pain, and weakness in the arm and hand. This is because of the radiotherapy on the nerves under the collarbone.

Getting another type of cancer (late malignancy)

There is an extremely small chance of getting another cancer in the treatment area, 10 or more years after treatment.