Intraoperative Radiotherapy (IORT) for Rectal Cancer Using the Photon Radiosurgery System (PRS): A Phase I Clinical Trial

Rectal cancer is usually managed by a combination of surgery and x-ray treatments (radiotherapy). The standard way of delivering radiotherapy is with external 'beams' directed at the tumour site. However, although in rectal cancer these treatments are effective, patients are often troubled by late side effects. An alternative option is to deliver the x-rays at the same time as surgery. This is known as intraoperative radiotherapy, or IORT, and a number of techniques have already been tried. There is a new IORT technology known as the Photon Radiosurgery System (PRS) which we are using to treat breast and brain cancers. Our experience to date has informed us that IORT with this x-ray source is safe and effective. We would like to use the technology to treat rectal cancer and believe that it may improve disease outcomes without the side effects associated with standard radiotherapy. We would also like to study the biological processes that follow radiation. It is not understood why some people are more sensitive to x-ray treatments than others. If we knew the reasons for this then we might be able to individualise treatments.