INTRODUCTION:Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer, especially in patients unfit for surgery, and intrathoracic oligo-metastatic disease. SBRT may benefit from intralesional placement of radio-opaque fiducial markers (FM) to ensure precise dose delivery and avoid radiation injury to mediastinal organs. We present a case series of 7 FM?s placement by endobronchial ultrasound (EBUS) in patients with metastatic involvement of intrathoracic lymph nodes (LN) and preliminary results.

CASE REPORT:7 patients were referred for FM placement via EBUS, with general anesthesia and via rigid bronchoscopy. The target LN were visualized with EBUS. After that, the needle?s stylet was partially withdrawn and the FM was introduced inside the needle. The LN was located again and punctured with the FM loaded needle. The stylet was advanced into the needle, deploying the FM under fluoroscopy.This procedure was repeated 2 times more in order to place 3 FMs in each lymph node in a triangle shape. SBRT was performed using FM-guided real-time tumor tracking with the CyberKnife Robotic radiosurgery system. A median of 3 fiducial markers were implanted. The median of total dose administered was 37 Gy. After the FM placement, no adverse events (AE), migration or malfunction. 

CONCLUSION: SBRT delivers high radiation doses and the FM is used to mark and track the target during the treatment session and account for tumor motion. Preliminary results showed promising efficacy in selected patients due to the possibility to deliver higher radiation dose directly to the target avoid healthy tissue.