Side effects of radiotherapy for penile cancer

Side effects tend to start a week after the radiotherapy begins. They gradually get worse during the treatment and for a couple of weeks after the treatment ends. But they usually begin to improve after around 2 weeks or so.

Everyone is different and the side effects vary from person to person. You may not have all of the effects mentioned. Side effects can include: 

Tiredness and weakness

You might feel tired during your treatment. It tends to get worse as the treatment goes on. You might also feel weak and lack energy. Rest when you need to.

Tiredness can carry on for some weeks after the treatment has ended. But it usually improves gradually.

Various things can help you to reduce tiredness and cope with it, such as exercise. Some research has shown that taking gentle exercise can give you more energy. It's important to balance exercise with resting.

Skin changes or skin soreness

Your skin might go red or darker in the treatment area. You might also get slight redness or darkening on the other side of your body. This is where the radiotherapy beams leave the body. 

The red or darker areas can feel sore. You may notice that it is itchy or feels warm to touch. During treatment your skin may also become dry and flaky, or can ooze and be painful. Do let your radiotherapy team know, they can help you cope with these symptoms.

The symptoms usually go away within 2 to 4 weeks of ending the treatment. But your skin might always be slightly darker in that area.

Tell the radiotherapy staff if you notice any skin changes.

 Tips for looking after your skin during radiotherapy

  • Wash or rinse the area with warm water. Showers are preferable to baths.

  • Gently dry the skin with a clean towel.

  • You can use a moisturiser on the area (but avoid using creams with perfumes). Check with your radiographer if you are unsure, they may be able to give you a soothing gel or recommend a particular type.

  • Wear loose fitting clothing made of natural fibres, such as cotton. This can help reduce irritation to the area.

Swollen penis

Your penis might become swollen and inflamed. This swelling can cause pain. Tell your doctor, nurse or radiographer if you have pain so that they can give you painkillers. The swelling goes down when you finish your treatment.

Long term side effects

Not everyone has long term side effects of radiotherapy. Long term side effects are more likely with higher doses of radiation. You are unlikely to have these with a short course of radiotherapy to help with your symptoms. 

The long term side effects start between a few months and a couple of years after your course of treatment. They can continue on for a lot longer and sometimes might be permanent.

Difficulty passing urine

Radiotherapy to the penis can make the urethra  narrower, which can make passing urine difficult and sometimes impossible. Doctors call this a stricture. It happens if the tissue inside the penis becomes thicker (fibrosis).

Tell your doctor or nurse if you have difficulty passing urine. You might need to have your urethra stretched (dilated). Or you may need surgery to widen the urethra.

Reduced blood supply to the penis

Radiotherapy can sometimes affect the blood flow to the treated area. This can cause problems in keeping the tissue healthy. The tissue may become starved of oxygen and nutrients.

If you notice any changes in the colour of your skin where you had treatment, tell your doctor straight away.

Difficulty in getting an erection

Most men are able to have sex after they've had radiotherapy. Getting an erection may be more difficult if you have:

  • thickening of the skin on the penis
  • problems with blood flow to the penis

Tell your doctor if you have any problems.

Swollen legs

Some people get swelling in one or both legs after radiotherapy to the lymph nodes in the groin and pelvis. This swelling is called lymphoedema.

More information

We have more information about the possible side effects of radiotherapy to the pelvis. 

  • Cancer: Principles and Practice of Oncology (12th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2023

  • EAU-ASCO Collaborative Guidelines on penile cancer 
    O R Brouwer and others 
    European Association of Urology, 2023 and American Society of Clinical Oncology 

Last reviewed: 
28 Feb 2024
Next review due: 
28 Feb 2027

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