Which method is best for placing fiducial markers before radiation for lung cancer?
Fiducial markers are small metal coils or seeds placed in or near a lung tumor to help a radiation machine track the tumor during treatment, such as with CyberKnife. For lung cancer patients, there are three main ways to insert these markers: through the chest wall (transthoracic), through a blood vessel (endovascular), or through the airways using a bronchoscope (endobronchial). A 2025 meta-analysis compared these approaches and found that endobronchial access had the lowest rate of inaccurate marker placement and a lower risk of pneumothorax (collapsed lung) compared to transthoracic access, while still providing high tracking success.
What the research says
A 2025 meta-analysis of 27 studies including 2,065 patients compared the three insertion methods for fiducial markers before stereotactic body radiotherapy (SBRT) for lung cancer 6. The study found that endobronchial access had the lowest rate of inaccurate marker placement (3.0%) compared to transthoracic and endovascular approaches 6. All three methods had high tracking success rates (over 97%), meaning the markers were reliably seen by the radiation machine 6. However, transthoracic access had the highest rate of pneumothorax (34.2%) and hemoptysis (coughing up blood, 3.5%), while endobronchial and endovascular approaches had much lower complication rates 6.
Other studies support the safety and effectiveness of endobronchial placement. One study of 54 patients using bronchoscopy with radial endobronchial ultrasound (R-EBUS) to place gold markers in small nodules (<20 mm) reported a 79% success rate for obtaining tissue samples during the same procedure, and markers remained visible on CT scans 3 months later 9. Another study of 52 patients using endobronchial coil spring fiducial markers found successful tracking in 93% of lung nodules, with a low migration rate of 8% and only one case of bronchospasm (no pneumothorax or hemoptysis) 10. A third study of 64 patients using electromagnetic navigational bronchoscopy (ENB) for fiducial placement reported an 82% marker retention rate and low complication rates, with no significant difference between upper and lower lobe lesions 11.
Overall, the evidence suggests that endobronchial access offers a good balance of accurate placement, high tracking success, and low complication risk. Transthoracic access may be an option when endobronchial access is not feasible, but it carries a higher risk of pneumothorax. Endovascular access also has low complication rates but requires specialized equipment and expertise.
What to ask your doctor
- Which fiducial marker insertion method (endobronchial, transthoracic, or endovascular) is recommended for my specific tumor location and size?
- What is the expected marker retention and tracking success rate with the proposed method at your center?
- What are the risks of pneumothorax or other complications with each approach, and how are they managed?
- Can fiducial marker placement be combined with a biopsy during the same procedure to reduce the number of procedures?
- How does your center's experience with each method affect the choice of approach?
This question is drawn from common patient questions about Oncology and answered using cited medical research. We do not provide individualized advice.