EUS-guided fiducial placement for stereotactic body radiotherapy in locally advanced and recurrent pancreatic cancer

Background: Stereotactic body radiotherapy (SBRT) has been approved for the treatment of locally advanced pancreatic cancer. Placement of gold fiducials is required for real-time tracking and delivery of a high-dose therapeutic beam of radiation to the tumor. Traditionally, fiducials have been placed either intraoperatively or percutaneously. Recently, EUS-guided fiducial placement has been reported, but the safety and feasibility of this approach is not well defined.

Objective: The aim of this study was to determine the safety, feasibility, and limitations of EUS-guided placement of 0.8 x 5.0 mm fiducials via a 19-gauge needle for locally advanced and recurrent pancreatic cancer.

Design: Prospective study of patients with either locally advanced or recurrent pancreatic cancer referred for EUS-guided fiducial placement for SBRT at our institution over a 3-year period.

Setting: Tertiary referral center conducting >1800 EUS procedures annually.

Main outcome measurements: Primary outcome measurements included success, complications, and technical limitations of EUS-guided fiducial placement in pancreatic cancer. In addition, the percentage of patients successfully completing SBRT after EUS-guided fiducial placement was determined.

Results: A total of 51 patients (mean age 73 years; 57% male) with locally advanced (n = 36) and recurrent (n = 15) pancreatic cancer were referred for EUS-guided fiducial placement. Fiducials were successfully placed in 46 patients (90%), with technical failures occurring in 4 patients (8%) with recurrent cancer after pancreaticoduodenectomy. In 3 patients (7%), the fiducials spontaneously migrated from the original site of injection, thereby requiring a second EUS procedure for placement of additional fiducials. Of the 46 patients with fiducials placed under EUS guidance, 42 patients (91%) successfully completed SBRT. Two patients experienced disease progression before SBRT, 1 patient was lost to follow-up, and 1 patient experienced a complication at ERCP that precluded further therapy. Only 1 complication (2%), of mild pancreatitis, occurred in a patient undergoing simultaneous placement of fiducials and celiac plexus neurolysis for intractable abdominal pain.

Limitations: Single-center experience and lack of a formal follow-up protocol to assess for complications.

Conclusion: EUS-guided fiducial placement for SBRT in locally advanced and recurrent pancreatic cancer is safe and feasible. Successful placement was achieved in 90% of patients, with a low complication rate (2%). Furthermore, 91% of patients successfully completed SBRT after EUS-guided fiducial delivery. Although fiducials can spontaneously migrate from the initial injection site, the rate of migration is relatively low (7%), and no migration-related complications occurred over the course of this study. Limitations to EUS-guided fiducial placement may include surgically altered anatomy (pancreaticoduodenectomy) in patients with recurrent pancreatic cancer.