Colorectal Cancer

Radiotherapy for bowel cancer

Radiotherapy (exposure to high powered rays) is one of the three main treatments for cancer of the rectum; it is seldom used to treat cancer of the colon. Radiotherapy may be used to shrink a tumour before surgery making it easier for the surgeon to remove, or to ensure (either before or after surgery) that no cancerous cells are left behind. 

The treatment itself is painless but may cause side effects such as burns (although this is very unusual these days), fatigue (tiredness), thirst, nausea, and diarrhoea. There can also be either temporary or permanent damage to other body parts in the pelvic region like the bladder and reproductive organs. 

For some patients radiotherapy was a painless and straightforward process; they experienced few if any side effects and none in the long term.

For others, the side effects were considerable. One man describes the burns caused by his radiotherapy and how he coped with them. Another explains how his side effects became more severe, and the recovery period longer with each treatment. He also hopes that the sexual dysfunction he has been experiencing will be temporary. A woman explains how she coped when her radiotherapy burned through to her vagina.

For a number of patients the side effects of radiotherapy were irreversible. One woman, who was in her late 40s, found that the treatment suddenly brought on the menopause. Another man was left permanently impotent by radiotherapy.

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Many people felt strongly that patients were not being given adequate information about the possible consequences of radiotherapy. The woman whose menopause was brought on by the treatment felt the same experience would have been much more traumatic for a younger person. Even people who had not suffered serious or lasting side effects felt they should have been better informed.

Several pointed out that knowing the risks would not have prevented them from having the treatment but would have helped them cope with the experience. The limited information they were given made things harder to deal with because they were inadequately prepared.

Being adequately informed about the possible consequences of radiotherapy has an impact on the patient's ability to participate in decision making about treatment. Radiotherapy was ruled out as a treatment in the case of one young woman because of the risk to fertility. A man who was given a choice between radiotherapy and surgery opted for surgery after being made aware of the risks by a radiotherapist. Another man whose cancer had been treated only with radiotherapy in the first instance, and who now lives with chronic discomfort as a result of the treatment, regretted having had it when his cancer recurred and he had to have surgery anyway.

A newer treatment for bowel cancer is high dose internal radiotherapy before surgery. This is called brachytherapy. A tube containing radioactive material is inserted into your rectum and positioned close to the tumour. It is left in place for a while. The aim is to shrink the tumour so that it is easier to completely remove it with surgery a few weeks later.

We have not yet been able to interview anyone who has had internal radiotherapy for bowel cancer. If you have had this type of treatment and you would like us to include your story on this website, please email

Donate to Last reviewed August 2016.
Last updated August 2016.


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