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Safe use of controlled doses of radiation to treat disease, especially cancer.  Usually given by pointing an X-ray machine at the part of the body to be treated, but can also be given by drinking liquid, having an injection or having a radioactive implant put into your body (brachytherapy).

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Northern Centre for Cancer Care

Radiotherapy to the Bowel (Colo-Rectal Tumours)

If an oncologist has advised you to have a course of radiotherapy to your bowel as part of your treatment for bowel cancer, this page gives you general information and answers some of the questions you may have about the side effects of radiotherapy.

We hope you will find this helpful. If you have any further questions relating to your treatment, please do not hesitate to ask your radiographer, nurse or oncologist.

Possible short term (acute) side effects

Acute side effects are temporary and affect all patients. The side effects generally develop during the second half of the course of treatment, last for several weeks after the treatment has finished and then slowly settle over the next three to four months.

Effects on the skin

Towards the end of treatment some patients experience some changes in the skin affecting the area that has been treated. The skin may;

  • Feel tight and uncomfortable
  • Become pink or red
  • Become dry and flaky
  • Itch

The reaction may be worse in areas where skin rubs together e.g. the skin between the buttocks and around the back passage particularly if you have diarrhoea.

This can also be a particular problem for patients having treatment for tumours of the anus, where groins and genital areas may also be affected. These reactions may be worse and happen earlier if you are also having chemotherapy.

You will be given moisturising cream to soothe the skin or your oncologist may prescribe a more active cream if necessary.

Your skin will be monitored by your radiographers during radiotherapy and you will be given advice on how to care for it. You will also be seen once a week in a radiotherapy clinic by your oncologist who will examine your skin and advise if any additional creams are necessary.

Skin reactions may sometimes persist for up to six weeks after treatment has finished.

Effects on the bowel

You may have more frequent bowel movements during your radiotherapy and for several weeks afterwards. You will normally be prescribed some medication to make the bowel more regular.

Effects on the bladder

Your bladder may become more irritable so that you pass urine more frequently, perhaps with some burning, sometimes called cystitis. It is important to drink plenty of clear fluids, avoiding large quantities of tea, coffee and alcohol. Many patients feel that cranberry juice and barley water can help to reduce these symptoms.

Your urine may be checked at the hospital to rule out any infection. If your symptoms are very troublesome you may need to be prescribed some medication by your oncologist.


Often nausea can be relieved by drinking fizzy drinks (especially tonic water), by eating little and often, and sticking to dry, non-fatty foods. Your oncologist can prescribe medication to help.

Tiredness / Fatigue

Radiotherapy can sometimes make you feel very tired especially towards the end of your course of radiotherapy and for a number of weeks following treatment. You should rest as much as you need to. It may be some time before you feel able to do some of your usual activities.

Fatigue is something nearly everyone with cancer feels. It affects people differently and it is important to tell the health care team if you are feeling more tired than usual.

There are some physical causes, such as anaemia that are readily treatable.

Please ask for a booklet on fatigue at the Information Centre in NCCC which may give you tips to help with this.

If you have a short course of radiotherapy (lasting one week) before you have surgery, you should not have these acute side-effects.

However, there is a very small risk of developing the long- term effects described below.

Possible long-term or permanent effects of treatment

  • Radiotherapy to the bowel or pelvic area is very likely to induce the menopause during the next three to four months in women who are having regular periods. Your oncologist may advise you to start hormone replacement therapy (HRT) if your symptoms are troublesome.
  • Some men may notice it is more difficult to achieve erection following a course of radiotherapy. In some patients this will improve, as you become fitter. There is a specialist service available for patients to discuss this problem. Please speak with your radiographer, nurse or oncologist for more information on where to access this service.
  • There is a risk of male or female infertility with any radiotherapy to the pelvis. You should speak to your oncologist if you would like further information about this, or if you feel your family is not complete.
  • The treatment carries a small long-term risk of damage to the bladder or bowel, which can require subsequent surgery. Your oncologist will discuss this with you before you start your radiotherapy.
  • There is a very small risk of damage to the sacral bone – this is the bone at the very bottom of your spine, again your oncologist will discuss this with you before you start your treatment.
  • Any radiotherapy treatment carries a very small risk of causing further cancers in the future. This risk is far outweighed by the benefit expected from the treatment you are to receive.

What can I do to help?

Skin care

We recommend that you take special care of your skin during and up to six weeks after your radiotherapy as the skin reaction may continue after treatment has finished.

  • Keep the area cool. You may find that using a hair dryer or fan set on a “cold” setting applied over the treatment area may help.
  • Wear loose, preferably cotton, clothing that does not rub the skin and will allow air to circulate. Women should avoid wearing tights and corsets, skirts and stockings are best.
  • Keep the treatment area out of the hot sun and do not use a sunbed, as this could worsen your reaction.
  • Do not soak the area in the bath or under a long hot shower. You may wash the treated area using a simple, unperfumed soap applying gently with your hands rinsing the area well with warm water. Avoid using flannels or sponges. Pat the treated skin with a soft towel, taking care of particular sensitive areas such as the groins and between the buttocks.
  • Do not use talcum powder, bubble baths, bath salts, shower gels or body lotions in the treated area as they tend to be highly perfumed and can dry or irritate the skin.


It is important that you continue to eat nourishing food during and after treatment. Ask the radiographers or nurses for a copy of the leaflet “Dietary Advice for Patients Having Radiotherapy”. Please ask to speak with the dietician who will give you further advice about coping with problems such as diarrhoea and loss of appetite.

How else can I help myself during treatment?

You can help by doing these things…

  • Don’t try to lose weight.
  • Try not to smoke. It can make your side effects worse.
  • Tell us if you are worried about your side effects, or if you feel unwell, or if you have any problems or questions.

Your progress

You will be seen by a member of your specialist team at least once a week during your treatment. This will be an opportunity to discuss any concerns or problems you may have.

Please tell your treatment radiographers if you have any problems between appointments.

Your emotions

It is important to make time for yourself. Emotions associated with the reactions to a diagnosis of bowel cancer may come to the surface at various stages during your treatment.

Don’t worry if you feel low, this is normal. If you need to talk to someone, please ask, we are here to help. We have a wide range of support services within the department, such as Macmillan nurses, dieticians and social workers.

You can visit The Macmillan Information Centre or Maggies if you have any concerns, the contact details for both of these and other services that may be of benefit are included at the end of this page.

A Clinical Psychology service is also available at the NCCC on referral from your oncologist.


Sexual activity is personal to each individual and may be an aspect of your life about which you have concerns relating to your disease or treatment. You may have questions you wish to ask. Please talk to your oncologist, nurse or radiographer if you would like to talk about these issues confidentially.

There is more information available in the Information Centre at NCCC.


It is very important that women are not and do not become pregnant whilst undergoing radiotherapy. Please inform a member of staff immediately if you think you may be pregnant. You will be asked (if appropriate) to confirm that you are not pregnant by one of the radiographers before starting treatment.

After your radiotherapy has finished

The side effects of treatment can continue for several weeks after radiotherapy has finished. Continue with your skincare routine until any changes return to normal.

On your last treatment you will be given a discharge letter with a copy for your GP summarising any side effects you may have and any creams or medication you have been prescribed at NCCC.

You will be sent a follow up appointment to see your specialist team four to eight weeks after treatment.

If you have had a short course of radiotherapy (one week) your progress will be reviewed by your surgeon. If you are worried about your side effects after your treatment has finished, please contact your colo-rectal nurse specialist at your referring hospital or the NCCC Information Centre for further advice.

More information

Useful contacts

Bowel Cancer UK: tel: 0800 840 3540,

Northern Centre for Cancer Care Macmillan Information and Support Centre, tel: 0191 213 8611
Opening hours Monday to Friday from 9.00am to 4.30pm 

Macmillan Cancer Relief, Head office tel: 020 7840 7840, freephone 0808 800 1234,     

Maggies Centre (Newcastle), tel: 0191 233 6600; email: 

Leaflet to download

Radiotherapy to the Bowel (Colo-Rectal Tumours).pdf

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