Radiation therapy for bowel cancer
Also known as radiotherapy, this uses a controlled dose of radiation, such as focused x-ray beams, to kill or damage cancer cells. The radiation treats only the area that the radiation is aimed at. This means there is less harm to the normal body tissue near the cancer.
Radiation therapy is often combined with chemotherapy (chemoradiation). This is because chemotherapy makes cancer cells more sensitive to radiation.
Learn more about:
- When radiation therapy is given
- Having radiation therapy
- Side effects of radiation therapy
- How radiation therapy affects sexual function and fertility
- Video: What is radiation therapy?
Radiation therapy may be recommended for rectal cancer but is not generally used to treat colon cancer.
Before surgery (neoadjuvant)
A short course of radiation therapy or a longer course of chemoradiation is used to shrink the tumour before surgery for rectal cancer. The aim is to make the cancer smaller so it is easier for the surgeon to completely remove the tumour and reduce the risk of the cancer coming back.
After surgery (adjuvant)
Occasionally, if the rectal cancer is found to be more advanced than originally thought, radiation therapy may be used after surgery to destroy any remaining cancer cells.
External beam radiation therapy is the most common type of radiation therapy for rectal cancer. Newer techniques deliver the dose to the affected area with little damage to surrounding tissue. This helps reduce the number of side effects from radiation therapy.
During treatment, you will lie on a treatment table under a machine called a linear accelerator. Each treatment takes only a few minutes, but a session may last 10–20 minutes because of the time it takes to set up the machine.
If radiation therapy is given with chemotherapy, you will have it once a day for 5–6 weeks, then there will be a gap of 6–12 weeks before surgery. This break allows the radiation therapy to have its full effect. If radiation therapy is given by itself, you will have a shorter course, usually for five days, then a shorter gap before surgery.
For more on this, see Radiation therapy.
The side effects of radiation therapy vary. Most are temporary and disappear a few weeks or months after treatment. Radiation therapy for rectal cancer is usually given over the pelvic area, which can irritate the bowel and bladder.
Common side effects include:
- feeling tired
- needing to pass urine (pee or wee) more often and burning when you pass urine (cystitis)
- redness and soreness in the treatment area
- faecal urgency and incontinence
- mucus discharge
- small amounts of bleeding from the anus.
Radiation therapy can also cause the skin or internal tissue to become less stretchy and harden (fibrosis). It can also affect fertility and sexual function.
People react to radiation therapy differently, so some people may have few side effects, while others have more. Your treatment team will talk to you about possible side effects and how to manage them.
Radiation to the pelvic area can damage the lining of the rectum causing inflammation and swelling (known as radiation proctitis). This can lead to a range of symptoms including diarrhoea and bleeding from the rectum, the need to empty the bowels urgently, and loss of control over the bowels (faecal incontinence).
These side effects may appear shortly after radiation therapy for rectal cancer, but are generally not a problem long term because the rectum is removed during surgery. Your treatment team will talk to you about the risk of developing radiation proctitis. Learn about some ways to cope with bowel changes.
Video: What is radiation therapy?
Download a PDF booklet on this topic.
A/Prof David A Clark, Colorectal Surgeon, Royal Brisbane and Women’s Hospital, and The University of Queensland, QLD, and The University of Sydney, NSW; A/Prof Siddhartha Baxi, Radiation Oncologist and Medical Director, GenesisCare Gold Coast, QLD; Dr Hooi Ee, Specialist Gastroenterologist and Head, Department of Gastroenterology, Sir Charles Gairdner Hospital, WA; Annie Harvey, Consumer; A/Prof Louise Nott, Medical Oncologist, Icon Cancer Centre, Hobart, TAS; Caley Schnaid, Accredited Practising Dietitian, GenesisCare, St Leonards and Frenchs Forest, NSW; Chris Sibthorpe, 13 11 20 Consultant, Cancer Council Queensland; Dr Alina Stoita, Gastroenterologist and Hepatologist, St Vincent’s Hospital Sydney, NSW; Catherine Trevaskis, Gastrointestinal Cancer Specialist Nurse, Canberra Hospital, ACT; Richard Vallance, Consumer.
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