Evaluation of a Novel Absorbable Radiopaque Hydrogel in Patients Undergoing Image-Guided Radiotherapy (IGRT) for Borderline Resectable and Locally Advanced Pancreatic Adenocarcinoma

Abstract Purpose We assessed the feasibility and safety of placing a radiopaque hydrogel in the pancreaticoduodenal groove via endoscopic ultrasound guidance in patients with borderline resectable/locally advanced pancreatic cancer (BR/LAPC). Methods and Materials Hydrogel injections were done at time of fiducial placement to form blebs in the pancreaticoduodenal groove. Patients subsequently underwent simulation computed tomography (sim-CT) followed by hypofractionated SBRT (33 Gy in 5 fractions). Four-to-eight weeks after SBRT, patients underwent CT re-evaluation for surgical candidacy and assessment of hydrogel location and size. Hydrogel placement was considered successful if identified in the pancreaticoduodenal groove on sim-CT scan. Stability was evaluated using equivalence testing analyses, with a null hypothesis of the presence of a >20% mean percentage change in volume and >2 mm change in the median and mean inter-bleb surface distance with a p-value Results Hydrogel placement was successful in 6 of the 6 evaluable patients. The average changes in median and mean inter-bleb distances were -0.43 mm and -0.35 mm, respectively, with p Conclusions These data demonstrate feasibility and safety of injecting a hydrogel marker in the pancreaticoduodenal groove in patients with BR/LAPC and set the stage for a follow-up clinical trial to place hydrogel as a spacer between the pancreatic tumor and dose-limiting, radiosensitive duodenum.