Key Point

EUS-FNA is a reliable and safe method for diagnosis and staging of lymph node metastases and sarcoidosis.

NEW YORK CITY—The main reason for poor survival in non–small cell lung cancer (NSCLC) is that many patients present for the first time with already advanced disease or metastases. Both confirmation of malignancy and accurate staging are essential for appropriate and timely treatment. In NSCLC, lymph node involvement is common. While mediastinoscopy is often used to acquire tissue samples from lymph nodes, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a promising alternative. Unlike mediastinoscopy, EUS-FNA can be used to obtain samples from posterior lymph nodes—without the need for general anesthesia, which carries an additional risk for the patient.

Three studies that were recently conducted in Australia, the United Kingdom, and the Netherlands have shown that EUS-FNA can successfully detect lymph node metastases that are not apparent on a CT scan.^1-3

A TOOL FOR BOTH DIAGNOSIS AND STAGING

In the Australian study,¹ 52 patients underwent mediastinal sampling by EUS-FNA between November 2002 and June 2004. Patients were under conscious sedation for the procedure.

A total of 72 FNAs were performed on 52 patients. Of these, 34 had enlarged mediastinal lymph nodes and/or a lung mass of unknown etiology, and the remaining 18 had an established diagnosis of stage I-IIIb NSCLC. The mean size of lymph nodes examined was 22.8 mm. Eighteen of the 34 patients with masses of unknown etiology were found to have NSCLC. In these patients, EUS-FNA served as both a diagnostic and staging tool.

In the same group of 34 patients, EUS-FNA provided a definitive diagnosis in 20. Of the remaining 14 for whom EUS-FNA was inconclusive, seven had a true-negative test result.

The authors observed that its ability to access lymph nodes from the posterior mediastinal stations makes EUS-FNA a complementary procedure to mediastinoscopy. They also pointed out, however, that EUS cannot reliably image anterior stations or more distant lymph node sites, such as lobar and interlobar sites.

EUS-FNA had excellent sensitivity, specificity, and positive and negative predictive values (Table).

BETTER ACCESS TO MEDIASTINAL LESIONS

Failure to identify mediastinal disease preoperatively is a major contributor to tumor relapse rates—even when the resection appears to be successful. Thus, the development of methods to improve the quality of mediastinal staging will also improve outcomes of initial treatment.

A group of UK researchers studied 20 patients with known or suspected lung cancer who were referred for endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) evaluation of mediastinal lesions. Six patients also underwent EUS-FNA.²

In this study, the use of both EBUS-TBNA and EUS-FNA offered the potential for more comprehensive access to mediastinal and hilar lymph nodes than is usually possible with mediastinoscopy alone. In addition, the authors wrote, “the ability to be able to guide the needle into lesions under real-time control allows not only accurate sampling of lesions < 1 cm in diameter, but also targeting of lesions in difficult locations.... [T]he number of passes required to successfully acquire tissue for cytological analysis is reduced, which increases safety and saves time.”

Additionally, in some cases, diagnosis using EBUS-TBNA or EUS-FNA bypasses the need for a mediastinoscopy and allows treatment to be started sooner than it otherwise would.

DIAGNOSING SARCOIDOSIS

In patients with suspected sarcoidosis, a biopsy is necessary to exclude malignant diseases or tuberculosis. This is often accomplished using bronchoscopy with transbronchial lung biopsy. However, about 30% of the time, bronchoscopy does not yield a diagnosis. The accuracy of EUS-FNA was studied by a group of Dutch investigators and was found to have a high yield in diagnosing sarcoidosis and should dramatically reduce the number of mediastinoscopies needed for confirmation.³

The study included 51 patients with a differential diagnosis of sarcoidosis. Thirty-six patients had previously undergone nondiagnostic bronchoscopy.

In 50 patients, a mean number of three biopsies were performed. EUS-FNA identified noncaseating granulomas in 82% of patients with suspected sarcoidosis. The lower yield in the diagnostic value of EUS-FNA that was seen in this study was probably due to the large number of patients (19) with stage II sarcoidosis, who tend to have more fibrotic lymph nodes than do patients with stage I sarcoidosis.3

The authors concluded that EUS-FNA “qualifies as the next diagnostic procedure after a nondiagnostic bronchoscopy and may significantly reduce the number of mediastinoscopies.”

—Gale Jurasek

Reference
1. Caddy G, Conron M, Wright G, et al. The accuracy of EUS-FNA in assessing mediastinal lymphadenopathy and staging patients with NSCLC. Eur Respir J. 2005;25:410-415.
2. Rintoul RC, Skwarski KM, Murchison JT, et al. Endobronchial and endoscopic ultrasound-guided real-time fine-needle aspiration for mediastinal staging. Eur Respir J. 2005;25:416-421.
3. Annema JT, Veseliç M, Rabe KF. Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of sarcoidosis. Eur Respir JM. 2005;25:405-409.

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