Long term side effects of brachytherapy for prostate cancer

Brachytherapy for prostate cancer can cause some long term side effects such as passing urine more often and difficulty getting an erection. 

Everyone is different and the side effects vary from person to person. You may not have all of the effects mentioned. Tell your doctor or nurse if you have any of these problems. They can help you to find ways of controlling the effects. 

About side effects

Your doctor will explain the risk of you getting certain side effects before you start treatment. But they won’t be able to tell you whether any of these side effects will definitely happen to you. Some side effects are more likely in some people.

You have a higher risk of side effects if you have brachytherapy as well as external radiotherapy.

Problems passing urine

You might have problems passing urine after the radiotherapy ends. It might be more difficult to pass urine at first and then gradually get easier over some months or years. This is due to the treatment causing a narrowing of the tube from the bladder to the penis (the urethra). The narrowing is called a urethral stricture.

Tell your doctor if you find it harder to pass urine.

You can have an operation to stretch it. This short operation is called urethral dilatation. They might slide a thin rod into the urethra to widen it. Or they may use a thin flexible tube with a light and camera on the end. They can see the narrowed area and put a tiny knife down the tube to cut away tissue and open up the urethra. You have these operations under local or general anaesthetic.

You might need to have this operation repeated if the urethra gets narrower again.

A small number of men find they can’t pass urine at all. This is called urine retention. If your tummy (abdomen) feels swollen and uncomfortable but you can’t pass urine, go to your local accident and emergency department. The staff there will put in a catheter to drain your bladder.

Leakage of urine

You may have some problems with leaking urine after treatment with brachytherapy. 

Your doctor or nurse can refer you to a specialist incontinence clinic if urine leakage becomes a long term problem. Staff at the clinic can help you with muscle exercises, bladder training and medicines.

Some men find that they can’t control their urine at all. This is very uncommon. If it happens you need to have a tube called a catheter into your bladder. The tube drains the urine into a bag.

Erection problems (impotence)

Radiotherapy can damage the nerves that control getting an erection.

Whether you have problems getting and keeping an erection depends on:

  • your age (impotence is less likely if you are under 65)

  • whether you have other health conditions

  • whether you had erection problems before the treatment

  • if you have hormone therapy before or after the radiotherapy

  • whether you have internal radiotherapy as well as external radiotherapy

Tell your doctor or specialist nurse as soon as possible if you have erection problems. They should refer you to a specialist to help you with this. 

Early treatment with medicines such as sildenafil (Viagra) might help you to get and keep erections.

Frequent or loose poo

Your bowel movements might be looser or more frequent than before your treatment.

You might need to take anti diarrhoea medicines, such as loperamide (Imodium). Bulking agents, such as Fybogel, might also help. Your doctor or nurse can prescribe these for you. Talk to your doctor before taking these.

It’s usually best to try to have a healthy balanced diet if you can. Try to eat small meals and snacks regularly. Ask with your healthcare team if you need to make any changes to your diet. Some people find it best to avoid high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables.

Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.

Let your doctor know if you have ongoing problems with frequent bowel movements or bleeding. They can refer you to a specialist team. The team includes:

  • cancer doctors
  • digestive system specialists
  • bowel surgeons
  • dietitians
  • specialist nurses

Inflammation of the back passage (proctitis)

Inflammation of the back passage (rectum) is a long term side effect. Proctitis can cause a feeling of wanting to strain whether or not you actually need to pass a bowel movement. You might also have bleeding from your back passage or a slimy mucous discharge.

Bleeding is usually slight but can be more severe for some people. Talk to your radiographer or nurse if you have proctitis. They might suggest you use treatments such as steroid suppositories for a short time. This might reduce the inflammation. 

Cancer of the bladder or lower bowel

A small number of men develop bladder cancer or cancer of the lower bowel (rectum) after radiotherapy for prostate cancer. This can happen many years after treatment.

It is important that you contact your GP if you notice blood in the urine or poo or a change in your bowel habits.

Coping and support for you and your family

Coping with the side effects of prostate cancer radiotherapy can be difficult. There are things you can do, and people who can help you and your family to cope. 

  • Prostate cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE), 2019. Last updated December 2021

  • Long-Term Efficacy and Toxicity of Low-Dose-Rate¹²⁵I Prostate Brachytherapy as Monotherapy in Low-, Intermediate-, and High-Risk Prostate Cancer
    JA Kittel and others
    International Journal of radiation oncology, biology, physics, 2015. Vol 92, Issue 4. Pages 884-894

  • Predictive factors for acute and late urinary toxicity after permanent prostate brachytherapy: long-term outcome in 712 consecutive patients
    M Keyes and others
    International Journal of radiation oncology, biology, physics, 2009. Vol 73, Issue 4. Pages 1023-1032

  • Secondary malignancies following radiotherapy for prostate cancer
    Petros and others
    Therapeutic Advances in Urology, 2010. Volume 2, Pages 119-125 

  • Incidence of urethral stricture after primary treatment for prostate cancer: data From CaPSURE
    SP Elliott and others 
    The Journal of Urology, 2007. Vol 178, Issue 2. Pages 529-534

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
23 Jun 2022
Next review due: 
23 Jun 2025

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