Bronchoscopic cs‐FM tied to low migration rate, allows precise SBRT delivery

Endobronchial coil spring fiducial marker (cs-FM) is a safe and rapid procedure that results in a low migration rate and allows precise stereotactic body radiation therapy (SBRT) delivery, a study has shown. Moreover, previous irradiation of the peripheral pulmonary lesion (PPL) appears to lead to a higher migration rate.

“Currently used techniques for FM placement have many limitations; transthoracic insertion has a high risk for pneumothorax, endovascular insertion requires expertise, and dedicated angiography infrastructure and endobronchial linear‐gold FM dislocate frequently,” the authors said.

This study evaluated the safety and efficacy of cs-FM endobronchial insertion under fluoroscopy with or without radial endobronchial ultrasound (R-EBUS) assessment. The authors retrospectively assessed all consecutive patients undergoing endobronchial cs-FM placement for at least one PPL <25 mm between October 2015 and December 2019.

In case of a typical R-EBUS signal, transbronchial biopsy (TBB) of the PPL was conducted. Finally, the authors analysed PPL tracking accuracy by CyberKnife, complications, cs-FM migration rate, and procedure duration.

Fifty-two patients were treated during 55 procedures, with 207 cs-FM placements in 70 PPL. Of the 70 PPL, 65 (93 percent) were successfully tracked. R-EBUS was performed for 33 (47 percent) PPL and TBB for nine (13 percent) PPL.

Bronchospasm and other complications occurred. Migration of cs-FM happened in 16 of 207 (8 percent) cs-FM placements and was more frequent when the target was in a previously irradiated area (p=0.022). The median bronchoscopy duration for 48 procedures was 31.5 min.

“SBRT is an alternative treatment for early‐stage inoperable lung cancer,” the authors noted. “Metallic FM allow[s] to increase tumour tracking precision by CyberKnife.”