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Christophe Dooms, MD, PhD; Kurt Tournoy, MD, PhD
Author and Funding Information

From the University Hospitals Leuven (Dr Dooms); and University Hospital Ghent and OLV Ziekenhuis Aalst (Dr Tournoy).

CORRESPONDENCE TO: Christophe Dooms, MD, PhD, Respiratory Division, University Hospitals Leuven, Herestraat 49, B-3000 Leuven, Belgium; e-mail: christophe.dooms@uzleuven.be


FINANCIAL/NONFINANCIAL DISCLOSURES: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;147(3):e122-e123. doi:10.1378/chest.14-3079
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To the Editor:

We thank Dr Annema for his thoughtful commentary on our recent article in CHEST1 on the Assessment of Surgical Mediastinal Staging Added to Endoscopic Ultrasound in cN1 Lung Cancer (ASTER2) study. In fact, it highlights an important reflection on the potential added role of transoesophageal endoscopic ultrasound (EUS) in addition to endobronchial ultrasound (EBUS) in the staging process of patients with lung cancer. Should invasive mediastinal nodal staging by EUS or EUS performed with the EBUS scope (EUS-B) be considered as “selected complementary to EBUS” or as “systematic combined with EBUS?”

A combined EBUS-EUS staging was proposed initially to adhere to a complete invasive mediastinal nodal mapping of stations 4R, 4L, and 7, at least. Several studies included in the meta-analysis by Zhang et al2 on combined endosonography considered the second endoscopic modality for mediastinal nodes that were inaccessible or difficult to access by the first endoscopic modality. In recent years, it has become clear that standard mediastinal nodal mapping (at least of stations 4R, 4L, and 7) is actually feasible with EBUS alone. As a consequence, an additional EUS or EUS-B is considered of added value in those patients with nodes inaccessible for EBUS. The argument of Dr Annema that EUS-B makes the sampling of 7 and 4L easier is acknowledged. However, there are no data showing that EUS-B is actually better than EBUS. An EBUS procedure is now the standard in most centers, and the systematic addition of EUS is not (yet) widely implemented.

Taking this into account, as well as the fact that for cN1 lung cancer a lobe-specific mediastinal examination is sufficient, the rationale for using EUS or EUS-B as a selected complementary test was clear when designing ASTER2. EBUS with transbronchial needle aspiration alone was performed in 75% of patients, whereas a combined procedure was carried out in 25%. We acknowledge the observation that in eight out of 14 patients with false-negative endosonography, the missed metastases were located in stations 4L, 7, or 8. These are reachable for EUS or EUS-B. However, in six of these (75%), the cytologic samples obtained by EBUS with transbronchial needle aspiration were representative for lymphoid tissue. That 25G needles, or a systematic EUS or EUS-B would have made the difference is possible (as discussed), but it remains to be shown for these particular cN1 patients.

Our conclusion, therefore, remains: Staging cN1 lung cancer with endosonography (either EBUS or EBUS with EUS-B in selected cases) has a low sensitivity. Whether EBUS with the systematic adding of EUS or EUS-B is effectively better in cN1 remains an open question.

References

Dooms C, Tournoy KG, Schuurbiers O, et al. Endosonography for mediastinal nodal staging of clinical N1 non-small cell lung cancer: a prospective multicenter study. Chest. 2015;147(1):209-215. [CrossRef] [PubMed]
 
Zhang R, Ying K, Shi L, Zhang L, Zhou L. Combined endobronchial and endoscopic ultrasound-guided fine needle aspiration for mediastinal lymph node staging of lung cancer: a meta-analysis. Eur J Cancer. 2013;49(8):1860-1867. [CrossRef] [PubMed]
 

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References

Dooms C, Tournoy KG, Schuurbiers O, et al. Endosonography for mediastinal nodal staging of clinical N1 non-small cell lung cancer: a prospective multicenter study. Chest. 2015;147(1):209-215. [CrossRef] [PubMed]
 
Zhang R, Ying K, Shi L, Zhang L, Zhou L. Combined endobronchial and endoscopic ultrasound-guided fine needle aspiration for mediastinal lymph node staging of lung cancer: a meta-analysis. Eur J Cancer. 2013;49(8):1860-1867. [CrossRef] [PubMed]
 
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