Original Report Surgical placement of biologic mesh spacers prior to external beam radiation for retroperitoneal and pelvic tumors Sam S. Yoon MD a, ⁎ , Yen-Lin Chen MD b , Avinash Kambadakone MD c , Benjamin Schmidt MD a , Thomas F. DeLaney MD b a Division of Surgical Oncology, Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts b Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts c Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts Received 5 April 2012; revised 19 June 2012; accepted 20 June 2012 Abstract Purpose: To determine the feasibility of surgical placement of biologic mesh spacers to displace bowel and other radiation-sensitive organs prior to external beam radiation for difficult retroperitoneal and pelvic tumors. Methods and Materials: Tumors were resected if possible, and intraoperative electron radiation therapy (IOERT) was directed to the tumor or tumor bed in selected patients. Biologic mesh spacers comprised of cadaveric human skin treated to remove cells and preserve extracellular matrix (Alloderm; Lifecell, Branchburg, NJ) were then placed around the tumor or tumor bed. External radiation techniques included proton beam radiation therapy (PBRT) and intensity modulated radiation therapy (IMRT). Results: Patients had primary sarcomas (n = 2), radiation-associated sarcomas (n = 1), or isolated metastases (n = 2) in the retroperitoneum or pelvis. One patient received preoperative radiation. Three tumors were marginally resected (R1 resection) while 2 tumors were left in situ, and 3 patients received IOERT (10-17 Gy) to the tumor or tumor bed. Up to 4 sheets of biologic mesh were used as spacers around the tumor or tumor bed to displace small bowel, colon, ureter, bladder, or pancreas. The average distance of the 4 closest organs prior to mesh placement was 1.3-9 mm and after mesh placement was 8.0-23.5 mm. Preoperative or postoperative radiation 36-76 Gy was delivered by IMRT or PBRT. There were no early complications from mesh placement and late complications possibly related to radiation included 1 vertebral body compression fracture and 1 deep vein thrombosis. There were no mesh-related infections and none of the meshes required removal. All 5 patients currently remain free of disease progression after 3-38 months. Conclusions: Biologic mesh spacers can be placed around tumors or tumor beds to displace radiation-sensitive organs and may allow for safer delivery of external beam radiation. © 2013 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved. Conflicts of interest: None. ⁎ Correspondence author. Division of Surgical Oncology, Department of Surgery, Massachusetts General Hospital, Yawkey 7B-7926, 55 Fruit St, Boston, MA 02114. E-mail address: syoon@partners.org (S.S. Yoon). www.practicalradonc.org 1879-8500/$ – see front matter © 2013 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.prro.2012.06.008 Practical Radiation Oncology (2013) 3, 199–208