Does radiotherapy treat bowel cancer?

Radiotherapy may be given before surgery to shrink or control a rectal tumour, or after surgery when local treatment is considered useful. It can also help relieve symptoms from bowel cancer that has spread to a specific area. Cancer in the colon is less often treated with pelvic radiation because of the position and movement of the bowel.

External radiotherapy is planned from scans so the beam reaches the intended area. Effects can include tiredness, skin irritation and changes in bowel habits. Your team will consider the tumour's location, scans, surgery plans, medicines and general health.

Ask whether the tumour is in the colon or rectum and why radiation is being recommended. Tell the team about diarrhoea, constipation, bleeding, abdominal pain, prior pelvic treatment, medicines and any stoma.

Follow the nutrition and bowel-care advice given by the oncology team. Report symptoms early, especially if bowel movements become much more frequent or you cannot keep fluids down.

Contact the treating team promptly for increasing rectal bleeding, persistent vomiting, severe abdominal pain, fever, marked dehydration or a new inability to pass stool or gas. Sudden severe pain, collapse or heavy bleeding requires urgent medical care.

Is my cancer in the colon or rectum, and what is the purpose of radiotherapy? Will it happen before or after surgery? How could it affect bowel function or a stoma, and which symptoms should be reported immediately?