Mediastinal restaging: EUS-FNA offers a new perspective☆
Introduction
Mediastinal restaging in non-small cell lung cancer (NSCLC) after induction chemotherapy remains a major problem. Computed tomography (CT) of the thorax has a low accuracy of only 58% and often overestimates the degree of local tumour regression [1]. Remediastinoscopy has a diagnostic accuracy of 80 respectively, 85% as shown in two small studies (n=24, n=27) [1], [2], however, a high number of incomplete procedures (40%) due to technical difficulties [3]. The current controversy about the effectiveness and implementation of remediastinoscopy in daily practice stimulates the search for alternative restaging methods [4].
Recent studies reported that NSCLC patients with ipsilateral lymph node metastases (IIIA-N2 disease), who were down-staged with induction chemotherapy [no regional lymph node metastasis] had a significantly prolonged survival after surgical resection compared to those with persistent N2 disease [5], [6], [7]. These studies demonstrate that patients without a pathological complete response after induction chemotherapy usually do not benefit from a surgical resection. Although an optimal treatment strategy for IIIA-N2 NSCLC with ipsilateral or subcarinal lymph node metastases is still under investigation, there is increasing evidence that multimodality treatment with induction chemotherapy significantly improves survival [8], [9], [10]. Considering the high prevalence of lung cancer and the poor overall survival of stage IIIA-N2 as a whole, it is a challenge to identify the subgroup of patients who are down-staged by induction chemotherapy to a complete pathologic response. After surgical resection these patients have a 4-year survival of 50% [7]. In addition, unnecessary surgical resection in patients with persistent N2 disease should be avoided. Restaging is important but the current available technique of remediastinoscopy is controversial.
Recently, the minimally invasive technique of transoesophageal endoscopic ultrasound guided fine needle aspiration (EUS-FNA) has become clinically available for the analysis of mediastinal lymph nodes (LN). An ultrasound transducer incorporated on top of an endoscope enables the investigator to visualize and puncture mediastinal LN under real-time ultrasound guidance. The procedure is well tolerated, safe and has a high diagnostic accuracy (89–95%) for the analysis of mediastinal LN [11], [12], [13], [14]. So far, no complications of EUS-FNA in the analysis of mediastinal LN have been reported [11], [12], [13], [14]. The advantages of this technique are multiple: tissue samples are obtained (in contrast to the imaging technique of CT) and the procedure itself is minimally invasive, is performed in an outpatient setting and can be repeated a number of times without technical difficulties (in contrast to mediastinoscopy).
In this preliminary study, we performed restaging of mediastinal lymph nodes with EUS-FNA in 19 patients with NSCLC and proven N2 disease (stadium IIIA) who had been treated with induction chemotherapy. Patients who were restaged by EUS-FNA to N0, underwent surgical resection of the tumour containing lobe or lung and LN sampling or dissection in order to confirm the complete pathologic response. We hypothesized that EUS-FNA has a high diagnostic accuracy in mediastinal restaging and that it is suitable and well tolerated in these patients.
Section snippets
Patients
Nineteen consecutive patients with NSCLC and proven stadium IIIA-N2 disease who had been treated with induction chemotherapy were referred to the Department of Pulmonology of the LUMC for mediastinal restaging by EUS-FNA between February 2001 and March 2003. All patients were accepted regardless of the localisation of the initial lymph node metastasis. Twelve of the 19 patients had previously undergone a mediastinoscopy for staging purposes during the initial lung cancer staging. The induction
Patients
Nineteen patients (6 female, 13 male), mean age 58 years (range 34–73) were included in the study. The primary tumours were predominantly located in the right lung; RUL (n=7), RLL (n=5), LUL (n=2) and LLL (n=5). The various tumour types were: squamous cell carcinoma (n=9), adenocarcinoma (n=7), large cell carcinoma (n=2) and adenosquamous carcinoma (n=1). The initial IIIA-N2 disease was established by mediastinoscopy (n=8), EUS-FNA (n=9), by both diagnostic techniques (n=1) or during
Discussion
We found that in patients with IIIA-N2 disease, EUS-FNA restaged the mediastinal lymph nodes after induction chemotherapy with a diagnostic accuracy of 83%. This is the first report of the concept using EUS-FNA for mediastinal restaging.
There were 3/18 false negative results (Table 1, Table 2). In patient 2 a sampling error must have been occurred as adequate material was aspirated by EUS-FNA from the lower paratracheal station. In patient 9 tumour was found during pneumectomy in a
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Supported by a grant from the Leiden University Medical Center. Technical support from Hitachi Ultrasound.