Endobronchial microcoil fiducial markers for stereotactic radiation therapy

Introduction: Stereotactic body radiation therapy (SBRT) is an alternative treatment for early stage lung cancer. Metallic fiducial markers (FMs) allow tumor tracking by CyberKnife®, increasing precision. Transthoracic FMs insertion is at high risk for pneumothorax, endovascular insertion is time consuming, and endobronchial linear-gold FMs frequently dislocate. The endobronchial insertion of spiral microcoil FMs (m-FMs), commonly used for endovascular procedures, will be assessed. Methods: We retrospectively evaluated all patients from 10.2015 to 11.2019 with at least one peripheral pulmonary lesion (PPL) Results: 52 patients were treated during 55 procedures and 207 m-FMs were placed for 68 PPL. At least one m-FM was not in the expected segment for 9 PPL (16 m-FMs, migration rate 8%). Among 7/16 migrated m-FMs, the target was in a previously irradiated area. R-EBUS was used for 33/68 PPL, TBB could be performed in 9 cases. Target tracking by Cyberknife® was possible for 64/68 PPL (tracking rate 94%). No complication occurred; median procedure duration was 31.5 minutes. Conclusion: Endobronchial m-FMs insertion for PPL is rapid and safe with a low migration rate. In previously irradiated areas, larger m-FMs may be a more appropriate option.