Current concepts in the mediastinal lymph node staging of nonsmall cell lung cancer

Size of noncancerous hilomediastinal lymph nodes measured on coronal and sagittal reconstruction CT images

PURPOSE

To determine the sizes of hilomediastinal lymph nodes on coronal and sagittal reconstruction computed tomographic images of subjects without known malignancies.

MATERIALS AND METHODS

We evaluated 560 lymph nodes of 246 consecutive patients who underwent multidetector-row computed tomography (MDCT) of the chest, then reconstructed coronal and sagittal images on a viewer and measured short-axis diameters of lymph nodes in each station according to the American Thoracic Society (ATS) map for axial, coronal, and sagittal images.

RESULTS

On coronal images, short-axis diameters were significantly larger than on axial images in station #4R (P < 0.01). On sagittal images, short-axis diameters were significantly smaller than on axial images in stations #4L (P < 0.01), #10R (P < 0.001), and #10L (P < 0.05). On coronal and sagittal images, short-axis diameters were significantly smaller than on axial images in stations #11R (P < 0.001). In #7, diameters were significantly larger on coronal images than on axial and sagittal images (P < 0.001), and diameters were significantly smaller on sagittal images than on axial images (P < 0.01).

CONCLUSION

In stations #4R, #4L, #7, #10R, #10L, and #11R, measurements of short-axis diameters of hilomediastinal lymph nodes differed on coronal and sagittal images. On coronal and sagittal images, evaluation of hilomediastinal lymph nodes requires unique size criteria for every station.

Non-invasive molecular imaging of prostate cancer lymph node metastasis

Imaging in medicine has been classically based on the anatomical description of organs. In the past 15 years, new imaging techniques based on gene expression that characterize a pathological process have been developed. Molecular imaging is the use of such molecules to image cell-specific characteristics. Here, we review recent advances in molecular imaging, taking as our prime example lymph node (LN) metastasis in prostate cancer. We describe the new techniques and compare their accuracy in detecting LN metastasis in prostate cancer. We also present new molecular strategies for improving tumor detection using adenoviruses, molecular promoters and amplification systems. Finally, we present the concept of 'in vivo pathology', which envisages using molecular imaging to accurately localize metastatic lesions based on the molecular signature of the disease.

Accuracy of helical computed tomography for the identification of lymph node metastasis in resectable non-small cell lung cancer

PURPOSE

The criteria for the diagnosis of lymph node metastasis (LNM) in non-small cell lung cancer were investigated using helical computed tomography (hCT). The conventional criterion (1-cm short axis threshold) is generally accepted; however, this criterion is based on conventional CT. New criteria for LNM were investigated because the resolution of hCT is better than that of conventional CT.

METHODS

Ninety-seven NSCLC patients examined with hCT were enrolled. Both the long axis (LA) and short axis (SA) of the nodes were measured using hCT.

RESULTS

Based on the receiver operating characteristic curves, the thresholds that gave optimal sensitivity and specificity for LNM were 13 mm for LA and 9 mm for SA. The LNM diagnosis was re-evaluated using the combination of cutoff values. When the LA was > or =13 mm and the SA was > or =9 mm, the sensitivity, specificity, and accuracy were 56.3%, 92.1%, and 88.1%, respectively. When the LA was > or =13 mm or SA was > or =9 mm, sensitivity, specificity, and accuracy were 75.0%, 74.7%, and 74.7%, respectively. These values were not so different from the conventional criterion recalculated from these data.

CONCLUSION

The new criteria are considered to be useful for making a LNM diagnosis. The conventional criteria for the LNM diagnosis might therefore be applicable even for hCT.

Positron Emission Tomography (PET) radiotracers in oncology--utility of 18F-Fluoro-deoxy-glucose (FDG)-PET in the management of patients with non-small-cell lung cancer (NSCLC)

PET (Positron Emission Tomography) is a nuclear medicine imaging method, frequently used in oncology during the last years. It is a non-invasive technique that provides quantitative in vivo assessment of physiological and biological phenomena. PET has found its application in common practice for the management of various cancers.Lung cancer is the most common cause of death for cancer in western countries.This review focuses on radiotracers used for PET scan with particular attention to Non Small Cell Lung Cancer diagnosis, staging, response to treatment and follow-up.

Integrated FDG-PET/CT does not make invasive staging of the intrathoracic lymph nodes in non-small cell lung cancer redundant: a prospective study

BACKGROUND

Staging of non-small cell lung cancer (NSCLC) is important for determining choice of treatment and prognosis. The accuracy of FDG-PET scans for staging of lymph nodes is too low to replace invasive nodal staging. It is unknown whether the accuracy of integrated FDG-PET/CT scanning makes invasive staging redundant.

METHODS

In a prospective study, the mediastinal and/or hilar lymph nodes in patients with proven NSCLC were investigated with integrated FDG-PET/CT scanning. Pathological confirmation of all suspect lymph nodes was obtained to calculate the accuracy of the fusion images. In addition, the use of the standardised uptake value (SUV) in the staging of intrathoracic lymph nodes was analysed.

RESULTS

105 intrathoracic lymph node stations from 52 patients with NSCLC were characterised. The prevalence of malignancy in the lymph nodes was 36%. The sensitivity of the integrated FDG-PET/CT scan to detect malignant lymph nodes was 84% and its specificity was 85% (positive likelihood ratio 5.64, negative likelihood ratio 0.19). SUV(max), SUV(mean) and the SUV(max)/SUV(liver) ratio were all significantly higher in malignant than in benign lymph nodes. The area under the receiver operating curve did not differ between these three quantitative variables, but the highest accuracy was found with the SUV(max)/SUV(liver) ratio. At a cut-off value of 1.5 for the SUV(max)/SUV(liver )ratio, the sensitivity and specificity to detect malignant lymph node invasion were 82% and 93%, respectively.

CONCLUSION

The accuracy of integrated FDG-PET/CT scanning is too low to replace invasive intrathoracic lymph node staging in patients with NSCLC. The visual interpretation of the fusion images of the integrated FDG-PET/CT scan can be replaced by the quantitative variable SUV(max)/SUV(liver) without loss of accuracy for intrathoracic lymph node staging.

Endoscopic ultrasound as a first test for diagnosis and staging of lung cancer: a prospective study

RATIONALE

Multiple tests are required for the management of lung cancer.

OBJECTIVES

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) was evaluated as a single test for the diagnosis and staging (thoracic and extrathoracic) of lung cancer.

METHODS

Consecutive subjects with computed tomography (CT) findings of a lung mass were enrolled for EUS and results were compared with those from CT and positron emission tomography scans.

RESULTS

Of 113 subjects with lung cancer, EUS was performed as a first test (after CT scan) for diagnosis in 93 (82%) of them. EUS-FNA established tissue diagnosis in 70% of cases. EUS-FNA, CT, and positron emission tomography detected metastases to the mediastinal lymph nodes with accuracies of 93, 81, and 83%, respectively. EUS-FNA was significantly better than CT at detecting distant metastases (accuracies of 97 and 89%, respectively; p = 0.02). Metastases to lymph nodes at the celiac axis (CLNs) were observed in 11% of cases. The diagnostic yields of EUS-FNA and CT for detection of metastases to the CLNs were 100 and 50%, respectively (p < 0.05). EUS was able to detect small metastases (less than 1 cm) often missed by CT. Metastasis to the CLNs was a predictor of poor survival of subjects with non-small cell lung cancer, irrespective of the size of the CLNs. Of 44 cases with resectable tumor on CT scan, EUS-FNA avoided thoracotomy in 14% of cases.

CONCLUSIONS

EUS-FNA as a first test (after CT) has high diagnostic yield and accuracy for detecting lung cancer metastases to the mediastinum and distant sites. Metastasis to the CLNs is associated with poor prognosis. EUS-FNA is able to detect occult metastasis to the CLNs and thus avoids thoracotomy.

Analysis of cytological specimens from mediastinal lesions obtained by endoscopic ultrasound-guided fine-needle aspiration

BACKGROUND

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) seems to be a powerful tool to obtain cytologic specimens from mediastinal and celiac lymph nodes, enlarged left adrenal glands, and intrapulmonary tumors with mediastinal extension. The diagnostic yield of EUS-FNA and the accuracy of cytologic specimens was evaluated.

METHODS

Cytologic assessment of EUS-FNA specimens was performed and specimens were classified as positive, negative, suspicious for malignancy, or unsatisfactory for diagnosis. Cytology was compared with histologic and clinical (> or = 6 months) follow-up.

RESULTS

Cytologic specimens were collected from 155 lymph nodes, 10 left adrenal glands, and 9 intrapulmonary tumor masses. For lymph nodes, the diagnostic yield was 0.65. After exclusion of unsatisfactory specimens, sensitivity, specificity, accuracy, and positive (PPV) and negative (NPV) predictive values of cytologic specimens were 0.92, 1.00, 0.93, 1.00, and 0.63, respectively. Subgroup analysis of lymph nodes with a dimension of > or = 10 mm showed similar results. With EUS imaging only, lymph node diameter and a round or irregular shape were significant predictors of malignancy at multiple logistic regression analysis, but their clinical usefulness is very limited (PPV = 0.78 and NPV = 0.45). For left adrenal gland specimens, sensitivity and specificity were 0.89 and 1.00, respectively. From intrapulmonary masses, 8 true-positive and 1 true-negative specimens were obtained.

CONCLUSIONS

Cytologic specimens from mediastinal or celiac lymph nodes obtained with EUS-FNA were reliable and accurate. Specimens from left adrenal glands and intrapulmonary tumor masses showed promising results.

Transesophageal ultrasound-guided fine needle aspiration improves mediastinal staging in patients with non-small cell lung cancer and normal mediastinum on computed tomography

The aim of the current study was to prospectively assess the value of transesophageal ultrasound-guided fine needle aspiration (EUS-FNA) in the mediastinal staging of patients with non-small cell lung cancer (NSCLC) and CT negative for lymph node (LN) metastases, candidates for surgical resection. EUS-FNA was performed using the standard technique and LNs with at least one morphological feature suggestive of malignancy were sampled. Pathological exam of surgical specimens or tumor positive cytology was used as gold standard. Forty seven patients were included, 21% of whom had advanced disease (pN2) undetected by CT. EUS-FNA demonstrated LN metastases in 50% of them (11% of the whole series), and there were no false positives, resulting in a sensitivity, specificity, positive and negative predictive values and accuracy of 50%, 100%, 100%, 88% and 89%, respectively. In conclusion, EUS-FNA improves mediastinal staging in patients with NSCLC and CT negative for mediastinal nodes. Therefore, EUS-FNA should be considered in any patient with NSCLC and no distant metastases before any therapeutic decision is taken.

The prognostic value of positron emission tomography in non-small cell lung cancer: Analysis of 266 cases

Positron emission tomography (PET) is more accurate than computed tomography (CT) in the staging of non-small cell lung cancer (NSCLC). We analyzed the prognostic value of PET for survival in NSCLC patients.

METHODS

Consecutive patients with proven NSCLC with PET for staging were selected. Staging by laboratory tests, bronchoscopy, chest X-ray, and CT was performed in all patients, leading to a clinical stage (c-TNM) prior to PET. A separate classification (pet-TNM) was obtained from PET images by observers blinded to clinical data. We performed univariate survival analysis with ECOG performance score, sex, weight loss, comorbidity, histology, c-TNM, and pet-TNM as variables. Cox regression analysis was performed with significant variables from the univariate analyses.

RESULTS

Two hundred and sixty-six patients were included, 205 men and 61 women. c-TNM and pet-TNM were identical in 150 (56%) patients, 69 were upstaged, and 47 were downstaged by PET. At time of analysis, 198 (74%) patients had died. Univariate analysis showed significant survival differences for ECOG performance score (0 versus 1/2), weight loss (<10% versus >or=10%), pulmonary comorbidity, c-TNM, and pet-TNM (stage IA versus IB, IIA, IIB, IIIA, IIIB, IV). Cox regression analysis identified pet-TNM as the most significant (p < 0.001) prognostic factor, followed by ECOG performance score (p = 0.018).

CONCLUSION

Tumor stage as determined by PET is the most significant prognostic factor for survival in patients with NSCLC.

The current status of FDG-PET in tumour volume definition in radiotherapy treatment planning

Positron emission tomography (PET) scan, mainly using 18 F-fluoro-deoxyglucose (FDG) as a tracer, is currently widely accepted as a diagnostic tool in oncology. It may lead to a change in staging and therefore in treatment management. PET can also be used to define the target volume in radiation treatment planning and to evaluate treatment response. In this review, we focused on issues concerning the role of PET in target volume delineation, both for the primary tumour and regional lymph nodes. A literature search was performed using MEDLINE. Furthermore, the following questions were addressed: does PET allow accurate tumour delineation and does it improve the outcome of radiotherapy, in terms of reduced toxicity or a higher tumour control probability? Combined computer tomography (CT) and PET information seems to influence target volume delineation. Using (CT-) PET scan, interobserver variability is being reduced. Only few studies compared delineation based on PET with pathologic examination, showing a complex relation. Preliminary results concerning incorporation of PET information in to target volume delineation varies in different tumour sites. In the field of lung cancer, incorporation of PET seems to improve tumour coverage and spare normal tissues, which may lead to less toxicity or the possibility to escalate dose. In oesophageal cancer and in lymphoma, PET scan can be used to include PET positive lymph nodes in the target volume. In most other tumour sites not enough data are currently available to draw definitive conclusions about the role of PET in radiation treatment planning.

Esophageal endoscopic ultrasound with fine-needle aspiration with an on-site cytopathologist: high accuracy for the diagnosis of mediastinal lymphadenopathy

STUDY OBJECTIVES

To analyze the accuracy of esophageal endoscopic ultrasound (EUS) with real-time, guided fine-needle aspiration (EUS-FNA) with an on-site cytopathologist in patients with (presumed) lung cancer presenting with mediastinal lymphadenopathy (ML) or a suspect left adrenal gland (LAG).

DESIGN

A single-center prospective study.

PATIENTS

Sixty-seven outpatients with (presumed) lung cancer with ML or a suspect LAG on either CT and/or positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) scan.

INTERVENTIONS

All patients underwent EUS-FNA under conscious sedation. A cytopathologist was present during all procedures.

MEASUREMENTS

EUS with and without fine-needle aspiration (FNA) as compared to FDG-PET was evaluated for accuracy in diagnosing cancer, safety, and rate of avoidance for further surgery.

RESULTS

Of 67 consecutive patients (56 men; median age, 64 years), malignant ML or LAG were found in 47 patients (70.1%). In 20 patients (29.9%) without EUS-FNA proof of malignancy, confirmation was obtained by surgical procedure in 13 patients (sarcoidosis [n = 5], infection [n = 1], lung cancer [n = 7]) or by clinical follow-up in 5 patients suggesting benign disease. Sixty-five patients were included in the calculation of test characteristics. With malignancy as an end point, the accuracy for EUS-FNA was 100%. This was better than EUS without FNA (accuracy, 75.4%; p < 0.001) or FDG-PET (accuracy, 75.0% [n = 28]; p = 0.0011). When using final histopathologic diagnosis as an end point, the accuracy of EUS-FNA was 92.3%, since EUS-FNA was unable to show noncaseating granulomas in those patients with sarcoidosis diagnosed after mediastinoscopy. Related to the presence of the in situ cytopathologist, there were no inconclusive samples. No adverse events were recorded, and 67.7% of surgical interventions were avoided following EUS-FNA.

CONCLUSIONS

The accuracy in this series of EUS-FNA with cytopathologist-assisted rapid on-site evaluation is high. The technique is safe and greatly reduces the number of surgical interventions.

Le bilan préopératoire du cancer bronchique

INTRODUCTION

The overall prognosis of non-small cell carcinoma of the bronchus (NSCLC) remains poor on account of frequently late diagnosis and associated co-morbidity preventing the optimal treatment of the tumour. Surgical resection remains the best curative treatment for limited stage disease.

STATE OF THE ART

The pre-operative assessment should determine whether the extent of the tumour permits complete resection and whether the physiological state of the patient would tolerate the curative resection required. The ultimate goal is to improve 5-year survival. In the case of initial inoperability the assessment should determine whether pre-operative oncological treatment might make an advanced tumour operable (e.g. stage IIIA), or whether targeted medical treatment might improve the patient sufficiently to tolerate an intervention initially judged too risky. The rapid development of the technical modalities available for the assessment requires a continuous review of the current practice guidelines. Positron emission tomography has considerably augmented the accuracy of classical radiological assessment. Nevertheless staging by imaging alone remains imprecise to the extent that invasive examinations are still necessary to provide histological proof of the clinical stage of NSCLC. The techniques for assessing mediastinal invasion are developing rapidly and becoming more accurate and less invasive. Mediastinoscopy enhanced by modern video technology, ultrasound guided endoscopic biopsies and thoracoscopy are complimentary rather than competing techniques. The functional assessment should estimate the operative risk of the proposed pulmonary resection, identify the targeted actions aimed at reducing this risk or, in the absence of such actions, suggest less invasive but less well validated surgical techniques or even palliative treatments. When the operative risk cannot be reduced its precise estimation at least allows the patient to decide whether the risk seems acceptable in relation to the chances of a cure.

VIEWPOINT AND CONCLUSIONS

In the future the pre-operative assessment of NSCLC should improve the detection of micro-metastases in order to optimise the choice of induction and adjuvant therapies. The increasing use of induction chemotherapy before surgical resection can only increase the importance of a detailed assessment for the selection of patients and the evaluation of results.

Selective mediastinal node irradiation based on FDG-PET scan data in patients with non–small-cell lung cancer: A prospective clinical study

PURPOSE

To evaluate the patterns of recurrence when selective mediastinal node irradiation based on FDG-PET scan data is used in patients with non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

A prospective Phase I/II study was undertaken on 44 patients with NSCLC without detectable distant metastases on CT and FDG-PET scan, delivering either 61.2 Gy in 34 fractions over 23 days or 64.8 Gy in 36 fractions over 24 days (1.8 Gy b.i.d. with 8-h interval). Only the primary tumor and the positive mediastinal areas on the pretreatment FDG-PET scan were irradiated. Isolated nodal failure was defined as recurrence in the regional nodes outside of the clinical target volume, in the absence of in-field failure.

RESULTS

The CT and FDG-PET stage distribution was as follows: Stage I: 8 patients (18%) and 13 patients (29%); Stage II: 6 patients (14%) and 10 patients (23%); Stage IIIA: 15 patients (34%) and 7 patients (16%); Stage IIIB: 15 patients (34%) and 14 patients (32%), respectively. After a median follow-up time of 16 months (95% confidence interval [CI], 11-21 months) postradiotherapy, 11 patients (25%) developed a local recurrence. Only 1 patient (crude rate, 2.3%; upper bound of 95% CI, 10.3%), with a Stage II tumor on both CT and PET, developed an isolated nodal failure. The median actuarial overall survival was 21 months (95% CI, 14-28 months), and the median actuarial progression-free survival was 18 months (95% CI, 12-24 months).

CONCLUSIONS

Selective mediastinal node irradiation based on FDG-PET scan data in patients with NSCLC results in low isolated nodal failure rates. In the Phase I component of this trial, radiation dose escalation up to 64.8 Gy in 36 fractions over 24 days is feasible.

Mediastinal adenopathy: finding the answer with endoscopic ultrasound-guided fine-needle aspiration biopsy

BACKGROUND

Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS FNA) is a relatively new imaging modality that has been reported to be useful for mediastinal nodal staging of lung cancer and for the evaluation of mediastinal adenopathy of unknown cause. However, the technique is not commonly used in Australia.

METHODS

A retrospective review of all patients who had mediastinal EUS FNA was undertaken. Of a total of 787 patients who had undergone endoscopic ultrasound (EUS) studies from November 1999 to March 2004, 27 patients were identified to have had mediastinal EUS FNA. Details were recorded including study indication, history of malignancy, source of referral, prior attempts for tissue diagnosis, EUS and EUS FNA findings, complications, surgical pathology if available and clinical outcome after diagnosis.

RESULTS

Mediastinal EUS FNA was performed on an outpatient basis and no complications were recorded. Diagnostic material was obtained from all patients with a mean number of three passes. Nodal stations sampled included left paratracheal, subcarinal, aortopulmonary window and inferior mediastinum. Indications for the studies included mediastinal adenopathy of uncertain cause (17), lung cancer staging (7) and gastrointestinal cancer staging (3). EUS FNA confirmed malignancy in 16/27 patients, sarcoidosis in three patients, tuberculosis in one patient and seven patients were deemed to have reactive adenopathy. Primary cytopathological diagnosis of malignancy was determined by EUS FNA in nine patients.

CONCLUSIONS

EUS FNA is a safe, efficient and effective modality for mediastinal staging of lung cancer and for the diagnosis of mediastinal adenopathy of uncertain origin. EUS FNA has the potential to significantly impact on patient management, avoiding more invasive procedures as well as unnecessary operations.

Value of FDG PET in the management of NSCLC

Metabolic imaging with positron emission tomography (PET) using 18F-fluoro-2-deoxy-glucose (FDG) has been accepted as an important imaging modality in lung cancer. FDG PET may have important impacts on the management of lung-cancer patients, for instance by improvement of locoregional (mediastinal) and extrathoracic staging (unexpected metastases). Interesting findings have now been reported in the response assessment to induction therapy providing results of greater prognostic significance than that obtained by conventional imaging methods. In the field of thoracic irradiation, FDG PET may provide advantages in terms of reduced toxicity, treatment intensification, better local tumour control and increased survival.

Oesophageal endoscopic ultrasound with fine needle aspiration improves and simplifies the staging of lung cancer

BACKGROUND

Positron emission tomography (PET) is accurate for mediastinal staging of lung cancer but has a moderate positive predictive value, necessitating pathological verification. Endoscopic ultrasonography with fine needle aspiration (EUS-FNA) is a technique for tissue verification of mediastinal and upper retroperitoneal abnormalities. The use of EUS-FNA may decrease the number of surgical procedures and thereby staging costs.

METHODS

EUS-FNA was used prospectively for the cytological assessment of mediastinal and/or upper retroperitoneal PET hot spots in patients with suspected lung cancer. Only if EUS-FNA was positive for malignancy was subsequent mediastinoscopy or exploratory thoracotomy cancelled. The cost effectiveness of EUS-FNA was determined.

RESULTS

Of 488 consecutive patients with suspected lung cancer, 81 were enrolled with mediastinal and/or upper retroperitoneal PET hot spots. EUS-FNA was positive in 50 (62%) patients, negative in six, and inconclusive in 25. Of the 31 negative or inconclusive patients, 26 underwent surgical staging (resulting in 14 patients with and 12 without mediastinal malignancy), while five patients had mediastinal metastases during follow up. No EUS-FNA related morbidity or mortality was encountered. The accuracy of the decision to proceed to surgery (or not) on the basis of EUS-FNA was 77% (95% CI 68 to 86). EUS-FNA detected more mediastinal abnormalities than PET except for the upper mediastinal region. Addition of EUS-FNA to conventional lung cancer staging reduced staging costs by 40% per patient, mainly due to a decrease in surgical staging procedures.

CONCLUSION

EUS-FNA can replace more than half of the surgical staging procedures in lung cancer patients with mediastinal and/or upper retroperitoneal PET hot spots, thereby saving 40% of staging costs.

FDG-PET in staging lung cancer

BACKGROUND

In patients with lung cancer, positron emission tomography (PET) using fluor-18-fluorodesoxyglucose (FDG) may be used both to detect extrathoracic metastases (ETM) and for mediastinal lymph node staging (MLS), potentially reducing the need for mediastinoscopy. We assessed the added value of FDG-PET in detecting ETM and focused on the reliability of FDG-PET and mediastinoscopy for MLS.

PATIENTS AND METHODS

In 72 consecutive patients with non-small cell lung cancer, the impact of adding FDG-PET to full conventional clinical staging was prospectively analyzed. The predictive value of FDG-PET findings and tumor location for pathologic mediastinal lymph node status were assessed in a logistic regression analysis.

RESULTS

Unexpected extrathoracic metastases were detected by FDG-PET in 15% of patients. In MLS overall negative and positive predictive values were 71 and 83% for FDG-PET, and 92 and 100% for mediastinoscopy. However, the negative predictive value of FDG-PET was only 17% in case of FDG-PET positive N1 nodes and/or a centrally located primary tumor, whereas it was 96% in case of FDG-PET negative N1 nodes and a non-centrally located primary tumor.

CONCLUSION

By incorporating FDG-PET in clinical staging, 15% of patients with lung cancer are upstaged due to unexpected extrathoracic metastases. In case of a negative mediastinal FDG-PET, mediastinoscopy can only be omitted in the presence of a non-centrally located primary tumor and without FDG-PET positive N1 nodes.