Inclusion Criteria:

- patients with histological or cytological proof of non small cell lung cancer (NSCLC)
or with a high clinical suspicion for lung cancer (but without pathologically
confirmed diagnosis from the bronchoscopy or CT guided transthoracal biopsies) in
whom the next step is normally a diagnostic or therapeutic surgical intervention

- no distant metastases after routine clinical work up (PET is optional, not mandatory)

- provision of a written informed consent

- recent CT-scan of the thorax (<28 days before randomization date)

- age 18 years or older

- clinically fit for surgery

Exclusion Criteria:

- proof of small cell lung cancer (SCLC) with CWU (bronchoscopy or CT guided
transthoracal punction)

- stage IV NSCLC

- patients with a solitary pulmonary nodule (thus without enlarged mediastinal lymph
nodes on CT and without mediastinal PET hot spots) : these do not require further
mediastinal investigation

- former therapy (chemotherapy or radiotherapy or surgery) for lung cancer

- other concomitant malignancies

- reasons for which the patient is unable to swallow the EUS-instrument (e.g. zenker
diverticulum, unexplained esophageal stenosis)

- uncorrected coagulopathy