Approaches for Lung Fiducial Markers Insertion in Stereotactic Body Radiotherapy

Background: Pulmonary fiducial markers (FMs) allow real-time tracking for stereotactic body radiotherapy (SBRT) by CyberKnife, which is an alternative to surgery in early-stage inoperable non–small-cell lung cancer (NSCLC) or intrathoracic oligometastatic disease. We conducted a systematic review and meta-analysis to compare the clinical performance and safety of 3 available approaches for FMs insertion for peripheral pulmonary lesions (PPL): transthoracic, endovascular, and endobronchial accesses. Methods: A systematic review with meta-analysis was performed by searching PubMed/MEDLINE and EMBASE databases for all articles on FM implantation before SBRT. Outcomes included clinical performance (inaccurate FM location and tracking rate) and per-procedural complications (pneumothorax and hemoptysis). We included 27 studies for a total of 2065 patients (627 with endobronchial access, 993 with transthoracic access, and 445 with endovascular access) and 4149 FMs insertions. Results: The lowest inaccurate FM location rate was found with nonlinear FM inserted by endobronchial access (0.030, 95% CI: 0.004-0.074). Tracking rate was high and similar with endobronchial (0.975, 95% CI: 0.949-0.994), endovascular (0.999, 95% CI: 0.941-1.000), and transthoracic approaches (0.985, 95% CI: 0.963-0.998). The highest rates of pneumothorax (0.342, 95% CI: 0.261-0.427) and hemoptysis (0.035, 95% CI: 0.015-0.060) occurred with the transthoracic access. Conclusion: While nonlinear FM insertion through endobronchial access achieved the lowest rate of inaccurate FM location, all 3 implantation approaches demonstrated high tracking feasibility for SBRT delivered using the CyberKnife system.