Intraoperative Electron Radiotherapy in Rectal Cancer - A Feasibility Trial

Rectal cancer is a cancer that occurs in the pelvis from the rectum. Locally advanced rectal cancer outgrows the rectum and attaches to other body parts in the pelvis and locally recurrent rectal cancer is a rectal cancer that comes back after surgery, and usually attaches to many different pelvic structures. They are both difficult to manage. The standard of care treatment involves chemotherapy and radiotherapy, followed by what is known as an extended margin operation to remove all cancer affected organs and not leave any cancer cells behind. If cancer cells reach the edge of the removed tissue, there is a high chance of leaving cancer cells behind. This is a key predictor of negative outcome in patients. Intraoperative electron beam radiotherapy (IOERT) was developed to help improve patient outcomes. Once the cancer has been removed, the surgeon and a cancer radiotherapy specialist examine the patient's scans, the cancer specimen and the area the cancer was in, and if there is concern about small numbers of cancer cells being left behind they treat the area with radiotherapy to destroy these cells. Patients that are due to receive treatment for these subsets of rectal cancer will be approached to take part. If eligible on the day of surgery the patient will be randomised to one of three arms: Arm A - standard of care (No IOERT), Arm B - extended margin surgery plus IOERT (10 Gy), or Arm C - extended margin surgery plus higher dose IOERT (15 Gy). The surgeon, cancer specialist team and patient will be blinded to study treatment. Patients will be followed up at 30 days, 3 months and for a minimum of 12 months post surgery as part of the trial and they will be followed up for 5 years as part of standard care.