Dec 062019
 

Electromagnetic navigation bronchoscopy (ENB) can allow biopsy of peripheral pulmonary nodules that are usually not accessible with conventional bronchoscopy. Navigational bronchoscopy requires specialized training and equipment costing hundreds of thousands of dollars, and is not widely available outside urban centers.

Multiple studies have reported varying yields and complication rates with ENB, but most have been retrospective case series performed by experts in the procedure, without longer term followup. A new study, NAVIGATE, was published aggregating results of ENB (the superDimension system) at 29 U.S. sites.

Among 1,215 patients with nodules (median 2.0 cm diameter) biopsied by ENB, 44% were positive for malignancy on the first ENB procedure (all of which were true positives).

Among the negatives (608), using 12 month follow up as the gold standard,

  • 284 were true negatives;
  • 220 were false negatives (later found to have cancer);
  • 104 were indeterminate or lost to follow-up at 12 months.

This translated to sensitivity of 69%, specificity 100%, positive predictive value 100%, and negative predictive value 56% for malignancy.

Only 3% of patients experienced pneumothoraces severe enough to require chest tubes or hospital admission.

The procedure ENB is positioned to compete with or replace is the community standard, CT-guided transthoracic needle biopsy (TTNB) with fine needle aspiration and core needle biopsies.

TTNB is generally considered to have a higher diagnostic yield for malignancy -- a sensitivity between 90 and 95% on the first attempt for lesions ≥ 3 cm, with lower yields for smaller lesions. However, this comes with a pneumothorax risk estimated at 10-15%.

One review estimated that using navigational bronchoscopy instead of CT-guided biopsy would avoid more complications (pneumothorax, hemothorax, respiratory failure), and performing ENB biopsy followed by CT-guided biopsy for negative ENBs might reduce complications, surgeries and costs overall.

A 2017 review of cases from University of North Carolina concluded that relative to CT-guided biopsy (77 cases), ENB's diagnostic accuracy (49 cases) was too low, and its costs too high to justify its use.

As the NAVIGATE authors point out, guidelines advise the lowest-risk procedure be employed to biopsy pulmonary nodules, especially because a significant proportion are benign. Navigational bronchoscopy meets this standard, but (as with most less-invasive approaches) with a higher likelihood of additional procedures to definitively rule out cancer.

The relatively high false-negative rate (220 of 608, or 36%) emphasizes the importance of vigilance after a negative biopsy obtained by ENB. CT-guided biopsy or serial imaging is essential in such cases, with repeat biopsy for any initially negative lesions found to be enlarging.

As with any rapidly evolving technology, the findings from NAVIGATE may already be out of date, as new iterations of electromagnetic bronchoscopy are regularly being deployed; any improvement in diagnostic accuracy and efficiency with the upgraded technologies is yet to be reported.

Source: J Thorac Oncol

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Navigational bronchoscopy real-world diagnostic yields reported