Is extensive abutment of the duodenum without invasion a contraindication to SBRT for pancreatic tumors?

First, let's be clear that we are talking about a palliative (or neoadjuvant) dose of radiation (53Gy BED). A similar dose, 54Gy in 30 fx, failed to improved overall survival in a randomized phase III trial (LAP07). Next, let's consider one of the most fundamental principles in radiotherapy, fractionation. With extensive abutment of a critical structure like the dudenum, why would you want to give high doses per fraction when it will either place the patient at risk of bleeding or lead to inadequate tumor coverage when there is no evidence of improved outcome from low dose SBRT anyway? Close to 2 dozen publications have shown a consistently modest outcome from low dose SBRT and no apparent benefit over what is achieved with standard chemoth...