Prospective Randomised Phase II Trial Evaluating Adjuvant Pelvic Radiotherapy Using Either IMRT or 3-Dimensional Planning for Endometrial Cancer. ICORG 09-06

Post-operative radiotherapy is internationally accepted as standard practice in the management of high-risk endometrial cancer1. Whilst it has no proven impact on overall survival it significantly increases local control. Conventional radiotherapy techniques (3-dimensional) utilise a 3 or 4 field beam arrangement to target the pelvis in order to treat those areas at risk of recurrence: the vagina, the parametrium and the pelvic lymph nodes. However, when using such a technique it is not possible to avoid irradiating sensitive normal tissues such as the bowel and bladder. Toxicity data from international randomised control trials in endometrial cancer report significantly more haematological, gastrointestinal, genitourinary and cutaneous toxicites (all grades) in those who received pelvic irradiation compared to those who did not2,3. These trials delivered radiotherapy using 2 or 3-dimensional techniques. Intensity Modulated Radiation Therapy (IMRT) is a newer but established radiotherapy technique in many tumour sites that allows us to much more tightly conform the radiation. It uses computer-generated beams to produce radiotherapy volumes that can avoid irradiation of normal tissues in the pelvis. There are no randomised studies reported in the literature that compare 3-dimensional pelvic irradiation with IMRT in patients who have had surgery for endometrial cancer. However there are several small studies that report considerable sparing of normal tissues using IMRT and when compared retrospectively with conventionally treated patients demonstrate marked reductions in acute gastrointestinal and genitourinary toxicity4. By delivering post-operative radiotherapy to the pelvis using IMRT (as opposed to the standard 3-dimensional technique) it is anticipated that whilst local control and survival will be unaffected acute and late toxicity will be reduced.