Expanding the boundaries of EUS: EUS-guided fiducial placement and fine-needle biopsy in oligometastatic disease of the adrenal gland

Background

Radiation therapy, including Intensity Modulated Radiation Therapy (IMRT) and Stereotactic Body Radiation Therapy (SBRT), is a crucial treatment for various malignancies, though side effects often arise from radiation exposure to healthy tissues. Fiducial markers are used in SBRT to optimize tumor targeting and minimize damage to surrounding tissues. Traditionally, fiducials are placed surgically or percutaneously, but EUS offers a safer, less invasive, and potentially cost-effective alternative. While fiducial placement within the pancreas has been well-studied, there are limited data on EUS-guided fiducial marker placement in non-GI organs, particularly the adrenal glands.

Methods

This retrospective case series evaluated EUS-guided fiducial marker placement in the left adrenal gland in 6 patients from 2020 to 2023. Patients were selected following multidisciplinary tumor board discussions, and all procedures were performed using a 22-gauge Menghini-tip needle under EUS guidance. Data were collected on patient demographics, tumor characteristics, technical success, and clinical outcomes following fiducial placement.

Results

The procedure was technically successful in all patients, with no reported adverse events. Four fiducials were placed in each patient, aiding SBRT planning. Five patients proceeded with SBRT, and 80% achieved a complete local response on radiological follow-up. No significant fiducial migration was noted. The findings suggest that EUS-guided fiducial placement for adrenal tumors is safe and effective.

Conclusion

This is the first case series demonstrating the safety and technical success of EUS-guided fiducial placement in the adrenal gland. This technique offers an alternative to more invasive approaches, facilitating precision radiotherapy for adrenal metastases, and highlights the expanding role of interventional endoscopists in oncology care. Further prospective studies are needed to validate these findings and expand their clinical application.