Clinical Investigation: Gynecologic Cancer A Phase II Study of Intensity Modulated Radiation Therapy to the Pelvis for Postoperative Patients With Endometrial Carcinoma: Radiation Therapy Oncology Group Trial 0418 Anuja Jhingran, MD,* Kathryn Winter, MS, y Lorraine Portelance, MD, z Brigitte Miller, MD, x Mohammad Salehpour, PhD,* Rakesh Gaur, MD, { Luis Souhami, MD, k William Small, Jr., MD,** Lawrence Berk, MD, yy and David Gaffney, MD, PhD zz *The University of Texas MD Anderson Cancer Center, Houston, Texas; y RTOG Statistical Center, Philadelphia, Pennsylvania; z University of Miami, Miami, Florida; x Carolinas Medical Center North East, Concord, North Carolina; { St. Luke’s Hospital, Kansas City, Missouri; k McGill University Health Centre, Montreal, Quebec, Canada; **Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illionis; yy H. Lee Moffitt Cancer Center, Tampa, Florida; and zz Huntsman Cancer Hospital, Salt Lake City, Utah Received Sep 12, 2011, and in revised form Feb 7, 2012. Accepted for publication Feb 20, 2012 Summary This is the first multi- institutional study evaluating the use of intensity modulated radiation therapy (IMRT) to the pelvis in the postoperative setting for patients with endometrial carcinoma. Guidelines for target defini- tion and delineation, dose prescription, and dose- volume constraints for the targets and critical normal structures were detailed in the study protocol and a web- based atlas. Pelvic IMRT for Purpose: To determine the feasibility of pelvic intensity modulated radiation therapy (IMRT) for patients with endometrial cancer in a multi-institutional setting and to determine whether this treat- ment is associated with fewer short-term bowel adverse events than standard radiation therapy. Methods: Patients with adenocarcinoma of the endometrium treated with pelvic radiation therapy alone were eligible. Guidelines for target definition and delineation, dose prescription, and dose- volume constraints for the targets and critical normal structures were detailed in the study protocol and a web-based atlas. Results: Fifty-eight patients were accrued by 25 institutions; 43 were eligible for analysis. Forty- two patients (98%) had an acceptable IMRT plan; 1 had an unacceptable variation from the prescribed dose to the nodal planning target volume. The proportions of cases in which doses to critical normal structures exceeded protocol criteria were as follows: bladder, 67%; rectum, 76%; bowel, 17%; and femoral heads, 33%. Twelve patients (28%) developed grade 2 short- term bowel adverse events. Conclusions: Pelvic IMRT for endometrial cancer is feasible across multiple institutions with use of a detailed protocol and centralized quality assurance (QA). For future trials, contouring of vaginal and nodal tissue will need continued monitoring with good QA and better definitions will be needed for organs at risk. Ó 2012 Elsevier Inc. Reprint requests to: Anuja Jhingran, MD, Department of Radiation Oncology, Unit 1202, 1515 Holcombe Blvd., Houston, Texas 77030. Tel: (713) 563-2347; Fax: (713) 792-3642; E-mail: ajhingra@mdanderson.org Supported by NCI grants RTOG U10 CA21661, CCOP U10 CA3742, and ATC U24 CA81647. This manuscript’s contents are the sole responsibility of the authors and do not necessarily represent the official views of the NCI. Conflict of interest: None. Int J Radiation Oncol Biol Phys, Vol. 84, No. 1, pp. e23ee28, 2012 0360-3016/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.ijrobp.2012.02.044 Radiation Oncology International Journal of biology physics www.redjournal.org