Side effects of bowel cancer radiotherapy

• A quick guide to what's on this page
• Short term side effects
• Long term side effects
• More information about radiotherapy

You may get some side effects while you are having the treatment. The effects usually start gradually during the course of treatment and carry on for a week or two after the treatment ends. You may have

• Diarrhoea
• Feeling sick
• Tiredness
• Passing urine more often
• Sore skin

Diarrhoea

Your doctor can give you medicines to reduce diarrhoea, so it is important to tell your doctor if you have it. There is information about dealing with diarrhoea in our section about bowel problems with cancer. It is important to drink plenty of fluids if you have diarrhoea.

Feeling sick

You may not feel like eating or drinking much if you are feeling sick. But it is important to drink plenty. If you are having trouble eating, try having high calorie drinks. You can get these on prescription, or buy them from your chemist. There is information about dealing with sickness in our section about symptoms and side effects.

Tiredness

You may find that you become more and more tired as your treatment goes on. This is very common with radiotherapy. It can be partly due to travelling back and forth to hospital each day for treatment. And partly just an effect of the treatment itself. Don't be afraid to rest if you feel you need to. It is good to try and get some gentle exercise each day. But if you feel that you want to have a lie down, then you probably need to do just that. There is more information about coping with tiredness in CancerHelp UK.

Passing urine more often

The rectum is very close to the bladder. So, bowel radiotherapy can irritate the lining of the bladder. You may feel as though you have cystitis (a bladder infection). You may want to pass urine all the time, but when you go there isn't much there. You may have a burning pain when you do pass urine.

Try to drink plenty of fluids. Many people find that drinking cranberry juice can be particularly helpful with bladder problems. Cranberry juice can increase the effects of warfarin (a blood thinner or anticoagulant). So don't start drinking cranberry juice if you are taking warfarin.

Your bladder inflammation will settle down after the treatment is over. But let your doctor know if you have any pain when passing urine in case you have an infection which needs antibiotic treatment.

Sore skin

Radiotherapy can make the skin sore. The skin round the anus is very sensitive and may get quite red and sore during your radiotherapy treatment. It is important to treat the skin very gently during treatment and for a few weeks afterwards. Wash the area with plain water and simple soaps such as baby soap. Gently pat the skin dry with a soft towel. Don't use perfumed or medicated soaps or any other lotions unless you have discussed them with your specialist, radiotherapy nurse, or radiographer.

You may have difficulty sitting comfortably for a while. Try using a soft cushion. You can also ask for help and advice from your radiotherapy nurse. The soreness will gradually get better over a few weeks after the end of treatment.

As well as short term side effects while you are having treatment, radiotherapy can cause long term side effects in some people. Your doctor will plan your treatment carefully to make sure you have as few side effects as possible. But radiation causes more side effects in some people than others.

Not everyone who has bowel cancer radiotherapy will have long term side effects. Some people get back to a normal life quickly after their treatment. But for some people the short term effects of treatment may continue and become long term effects. For other people, the short term effects may get better but then signs of long term changes to the bowel or bladder may begin. These can start from a few months to a couple of years after finishing your course of treatment. The long term effects of radiotherapy to the bowel include

• Diarrhoea, which may come and go
• Needing to have your bowels open very often
• Poor absorption of food from your gut, leading to weight loss
• The bladder wall becoming less stretchy, so you have to pass urine more often
• Fragile blood vessels in the wall of your bladder, so you may get blood in the urine
• Loss of fertility for men and women
• Leaking of urine (incontinence)
• Early menopause
• Dryness and shrinkage of your vagina making sex painful
• Difficulty getting an erection

Talk to your doctor if you think you have developed any of these side effects. There are ways of reducing and managing them. Sometimes other conditions, such as infections, can cause similar symptoms to the long term side effects of bowel cancer radiotherapy. So you can usually have treatment for the condition causing the effects.

You may feel very embarrassed to talk to doctors or nurses about effects such as diarrhoea, narrowing of the vagina or leaking of urine (incontinence). But the doctors and nurses deal with these effects all the time so you don't need to feel embarrassed. If you tell your healthcare team about the effects that you have, they can find ways of helping you to deal with them.

Look in the radiotherapy section of CancerHelp UK for detailed information about radiotherapy and side effects. There is information about dealing with the side effects of pelvic or stomach radiotherapy which you may find helpful.

There is more information about coping with early menopause, vaginal dryness and difficulty getting an erection in the sex and sexuality section of CancerHelp UK.