Radiation therapy (Radiotherapy)

Radiotherapy uses high-energy X-rays or particles to destroy cancer cells. It is used more often for rectal cancer than colon cancer.

There are three main ways radiotherapy is used to treat colorectal cancer: before surgery to shrink the tumour (often in combination with chemotherapy), instead of surgery to cure or stop the spread of early-stage rectal cancer, and during palliative care, to help slow the advance of the cancer.

Radiotherapy can be given in several ways:

• External beam radiation therapy (EBRT): a machine beams high-energy waves at the affected area. Each treatment lasts a few minutes and is performed as an outpatient procedure.
• Internal radiotherapy (brachytherapy): a tube is inserted into the anus and placed as close as possible to the cancer in the rectum. It then releases radiation directly to the tumour, while limiting damage to surrounding tissue. You may have to travel to a specialist centre to receive this treatment.
• Selective internal radiation therapy (SIRT or radioembolisation): for patients with advanced colorectal cancer that has spread to the liver. SIRT is a targeted treatment for liver tumours that delivers millions of tiny radioactive beads directly to the liver tumour.