Radiotherapy for rectal cancer

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 often given in combination with chemotherapy, which is called chemoradiotherapy. The chemotherapy makes the cancer cells more sensitive to radiotherapy.

Radiotherapy doesn’t make you radioactive and it’s perfectly safe for you to be with other people, including children, throughout your treatment.

Radiotherapy for early-stage rectal cancer Back to top

Radiotherapy may be given before surgery to shrink a cancer and make it easier to remove. It also reduces the chance of the cancer coming back.

A short course of radiotherapy consisting of five treatments may be given over a week, just before the surgery.

If the cancer is large, a long course of radiotherapy may be given, lasting for up to six weeks. This is usually given with chemotherapy (chemoradiotherapy), which can help make the radiotherapy more effective. Following the course of radiotherapy you’ll have to wait up to six weeks for the side effects to settle down before you can have the operation. 

If radiotherapy was not given before surgery, you may have it afterwards if:

• the cancer was difficult to remove
• some cancer cells may be left behind
• the cancer had spread through the bowel wall or into nearby lymph nodes.

This type of radiotherapy may be given as treatment every weekday for 4–5 weeks.

Radiotherapy for secondary rectal cancer Back to top

If a rectal 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.

How radiotherapy is given Back to top

Radiotherapy for rectal cancer is usually given as an outpatient in the radiotherapy department as a series of short daily treatments. The radiotherapy is given using equipment similar to a large x-ray machine and is known as external radiotherapy. The treatments are usually given each weekday with a rest at the weekend. How the treatment is given varies, depending on what is considered to be most effective for your situation. 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.

Planning your treatment Back to top

To make sure that your radiotherapy is as effective as possible, it has to be carefully planned. Planning ensures the radiotherapy rays are aimed precisely at the cancer and cause the least possible damage to the surrounding healthy tissues. 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 it’s over. At the start of your radiotherapy you’ll be told how to look after the skin in the area to be treated.

What happens in your treatment sessions

Before each session of radiotherapy, you’ll 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’ll be left alone in the room, but you can talk to the radiographer who will watch you from another room. Radiotherapy isn’t painful but you do have to be still for a few minutes during treatment.

Side effects of radiotherapy for rectal cancer Back to top

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 get better. 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.

Feeling sick

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.

Diarrhoea

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.

Tiredness

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.

Skin reaction

The skin in the area that is treated may become red and sore. Many people find this is mild, but for others, the skin can become very sore and painful. The nurses and radiographers can advise you on how to look after your skin during treatment. If your skin gets very sore, soothing creams can be prescribed.

Inflammation of the bladder lining (cystitis)

Radiotherapy to the rectum 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 medicine to 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’s important to let your doctor know if they continue.

Possible long-term side effects of radiotherapy Back to top

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 months or years before these side effects develop. If you notice any bleeding, it’s important to let your doctor know so that you can have tests and appropriate treatment.

We have sections on the possible long-term side effects of pelvic radiotherapy for men| and women|.

Infertility and impotence

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 distressing and it’s 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.