By Mark Weir, MBChB, MRCP
Lung cancer is the leading cause of cancer death worldwide. Stage 1 non-small-cell lung cancer can be effectively cured by surgery or radiotherapy, but Stage 4 lung cancer carries a very poor prognosis. Improved survival depends on diagnosing lung cancer in the early asymptomatic stages; the only effective way of doing this currently is CT-based lung cancer screening to identify nodules for evaluation and risk-stratification (usually those 8 mm or larger). The ability to efficiently biopsy and accurately diagnose CT-identified high-risk lung nodules will be key to improving overall survival of this devastating disease, and bronchoscopic techniques stand to play an increasingly important role.
Bronchoscopic biopsy techniques carry a lower risk of pneumothorax and bleeding compared with CT-guided needle biopsies, a difference that is especially important in patients with other advanced lung disease. However, while bronchoscopic techniques can be combined with simultaneous mediastinal staging, the diagnostic yield is less than transthoracic needle biopsy under CT guidance. However, transthoracic needle biopsy has an increased rate of pneumothorax, and can’t be performed in many patients with advanced lung disease or anatomic concerns. Of the three most common bronchoscopic techniques, radial endobronchial ultrasound (R-EBUS), when combined with electromagnetic navigational bronchoscopy (ENB), increases the diagnostic yield—but that varies widely based on operator, nodule location, size and presence of a ‘bronchus sign.’ Nodules distal to the bronchial tree also pose a diagnostic difficulty for bronchoscopic techniques.
Novel bronchoscopic methods are being developed that will allow improved diagnostic accuracy with minimal complications and may even facilitate treatment of early-stage lung cancer. New image-guided bronchoscopic methods, such as the Archimedes system, are allowing Temple Health to reach previously unattainable nodules using a tunneling technique. Trials are currently underway to determine the efficacy and refinement of this technology, including the recent EAST 2 trial at Temple.
Endobronchial ablation treatments are also under investigation.
Interest in robotic bronchoscopic techniques is increasing. Robotic bronchoscopes have a greater degree of maneuverability combined with reduced diameter, and therefore can theoretically make use of much smaller airways to reach a nodule. Two new robotic systems—the Ion system and the Monarch Platform, both FDA approved in 2018–2019—await further use and data collection to confirm their reliability and accuracy in a clinical setting.
An additional image-guided technique under preliminary investigation is cone beam CT biopsy, which could be particularly promising for peripheral lung nodules. Cone beam CT allows for real-time 3D CT guidance and location confirmation (as well as renavigation, if necessary) and appears to have a relatively low-risk profile in preliminary trials. If such techniques prove reliable, researchers speculate that they could then provide a platform for treatment of confirmed cancerous nodules bronchoscopically (with, for example, a radiofrequency ablation catheter), sparing vulnerable patients from invasive surgical procedures. That’s all in the future, but the future is looking closer than ever.
To learn more about bronchoscopic nodule biopsy trials at Temple, call 215-707-1359. ■