Increased bowel toxicity in patients treated with a vascular endothelial growth factor inhibitor (VEGF-i) following stereotactic body radiotherapy (SBRT).

e14507 Background: Serious gastrointestinal injury (SGI) is a rare but documented side effect that can occur independently with agents that affect the vascular endothelial growth factor (VEGF) receptor or with stereotactic body radiotherapy (SBRT). The risk of SGI in patients treated with the combination of SBRT sequentially followed by a VEGF inhibitor (VEGF-i) is not yet quantified. We explored the incidence of SGI in patients treated with SBRT with or without VEGF-i therapy at a single institution. Methods: From May 2008 to August 2011, 76 patients with 84 primary or metastatic intraabdominal lesions underwent SBRT (median dose, 50 Gy in 5 fractions). Twenty of these patients (26%) received a VEGF-i within two years of completing SBRT (bevacizumab, n=14; sorafenib, n=4; pazopanib, n=1; sunitinib, n=1). The most common site treated with SBRT was the liver (n=43, 57%), and the most common histology was colorectal adenocarcinoma (n=18, 24%). Other common histologies included melanoma of the skin (n=14, 18...