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Radiotherapy treats cancer by using high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. Radiotherapy is usually only used to treat cancer of the rectum. It is not normally used for colon cancer except occasionally to relieve symptoms.
Radiotherapy does not make you radioactive and it is perfectly safe for you to be with other people, including children, throughout your treatment.
Radiotherapy may be given before surgery to shrink a tumour and make it easier to remove. It also reduces the chance of the cancer coming back. Usually a course of five treatments is given a week before the surgery. If the tumour is large, a longer course of radiotherapy may be given, lasting for up to six weeks and this is usually given with chemotherapy (chemoradiotherapy).
If radiotherapy was not given before surgery, you may have radiotherapy afterwards:
If a bowel cancer has spread or come back after initial treatment (particularly in the pelvic area), radiotherapy may be used to shrink the cancer. It also relieves symptoms such as pain.
Radiotherapy is usually given at a hospital outpatient clinic as a series of short daily treatments. The treatments are usually given each weekday with a rest at the weekend. How the treatment is given can vary a lot, depending on what is considered to be most effective for your cancer and best for you. The course may last for just one week or a few weeks. Your doctor will discuss your treatment with you beforehand, including how it will be given and how long it will last.
To make sure that your radiotherapy is as effective as possible, it has to be carefully planned. On your first visit to the radiotherapy department, you will be asked to lie under a large machine called a simulator, which takes x-rays and scans of the area to be treated. Sometimes a CT scanner can be used for the same purpose. The treatment is planned by a specialist doctor known as a clinical oncologist. Planning is very important and may take a few visits.
Marks may be drawn on your skin to help the radiographer, who gives you your treatment, to position you accurately and to show where the rays are to be directed. These marks must stay visible throughout your treatment, but they can be washed off once your course is over. At the beginning of your radiotherapy you will be told how to look after the skin in the area to be treated.
Before each session of radiotherapy, you will be carefully positioned on the couch, either sitting or lying. The radiographer will make sure that you are comfortable. During your treatment, which only takes a few minutes, you will be left alone in the room, but you will be able to talk to the radiographer who will be watching you carefully from the next room. Radiotherapy is not painful but you do have to be still for a few minutes while your treatment is being given.
Radiotherapy to the bowel area can cause side effects, such as diarrhoea, feeling sick (nausea) and tiredness. It can also cause more specific side effects, such as inflammation of the bowel or bladder lining. These side effects can be mild or more troublesome, depending on the strength of the radiotherapy dose and the length of your treatment, but they tend to get worse as the treatment goes on.
The side effects will usually continue until a week or so after the treatment has finished, and then will gradually start to disappear. Your clinical oncologist will tell you what to expect, and you can ask your radiographer for advice if side effects are becoming a problem for you.
Some people may feel sick (nauseated) but this is usually mild, and anti-sickness drugs (anti-emetics) can usually control this effectively. If you don’t feel like eating, you can replace meals with nutritious, high-calorie drinks. These are available from most chemists and can also be prescribed by your GP.
Radiotherapy may irritate the bowel and cause diarrhoea. Your doctor can prescribe drugs to reduce this.
Our section on diet gives helpful hints on coping with problems such as nausea and diarrhoea.
As radiotherapy can make you feel tired, try to get as much rest as you can, especially if you have to travel a long way for treatment each day.
The skin in the area that is being treated may become red and sore. Many people find that this is mild, but for others, the skin can become very sore and painful. The nurses and radiographers will give you advice on how to look after your skin during treatment. If your skin gets very sore, soothing creams can be prescribed.
Radiotherapy to the bowel may cause inflammation of the lining of the bladder. This can make you feel as though you want to pass urine often. You may also feel a burning sensation when you pass urine. It helps to drink plenty of water and other fluids to make your urine less concentrated. Your doctor can prescribe a medicine which can make passing urine more comfortable.
These side effects generally continue for several weeks and then disappear gradually once the course of treatment is over. It is important to let your doctor know if they continue.
In some people, the bowel or bladder may be permanently affected by the radiotherapy. If this happens, the increased bowel motions and diarrhoea may continue, or you may need to pass urine more often than before. The blood vessels in the bowel and bladder can become more fragile after radiotherapy treatment and this can make blood appear in the urine or in bowel movements. It can take many months or years before these side effects develop. If you notice any bleeding, it is important to let your doctor know so that tests can be done and appropriate treatment given.
We have a section on the possible long-term side effects of pelvic radiotherapy.
Radiotherapy to the pelvic area is very likely to cause infertility in men and women. Men may find that they become impotent due to the effect of the radiotherapy on the nerves in the pelvic area. Women may find that sensations during sex are different. These effects can be very distressing if they occur. It is important to discuss them with your doctor or specialist nurse, who can help you to find ways of dealing with them.
Our section on sexuality and cancer has advice on coping with impotence.
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