***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Endobronchial ultrasound-guided transbronchial needle aspiration ( EBUS-TBNA ) can reliably sample enlarged mediastinal lymph nodes in patients with non-small cell lung cancer ( NSCLC ) , and in practice is mostly used to sample nodes visible on CT or positron emission tomography ( PET ) . Few data are available on the use of endoscopic procedures to stage the mediastinum in clinical stage 1 lung cancer . The aim of the present study was to determine the results of EBUS-TBNA in sampling mediastinal lymph nodes in patients with lung cancer and a radiographically normal mediastinum and no PET activity . From January 2004 to May 2007 , patients highly suspicious for NSCLC with CT scans showing no enlarged lymph nodes ( no node > 1 cm ) and a negative PET finding of the mediastinum underwent EBUS-TBNA . Identifiable lymph nodes at locations 2r , 2L , 4r , 4L , 7 , 10r , 10L , 11r , and 11L were aspirated . All patients underwent subsequent surgical staging . Diagnoses based on aspiration results were compared with those based on surgical results . One hundred patients ( mean age , 52.4 years ; 59 men ) were included . After surgery , 97 patients ( mean age , 52.9 years ; 57 men ) had NSCLC confirmed and were included in the analysis . In this group , 156 lymph nodes ranging 5 to 10 mm in size were detected and sample d. Malignancy was detected in nine patients but missed in one patient . Mean diameter of the punctured lymph nodes was 7.9 mm . The sensitivity of EBUS-TBNA for detecting malignancy was 89 % , specificity was 100 % , and the negative predictive value was 98.9 % . No complications occurred . In conclusion , EBUS-TBNA can be used to accurately sample and stage patients with clinical stage 1 lung cancer and no evidence of mediastinal involvement on CT and PET . Potentially operable patients with no signs of mediastinal involvement may benefit from presurgical staging with EBUS-TBNA OBJECTIVE This study sought to assess the real incidence of pN2 among patients with non-small-cell lung cancer ( NSCLC ) ( cN0 ) with negative mediastinal uptake of 2-deoxy-2-(18F)-fluoro-o-glucose ( FDG ) . METHODS During 30 consecutive months ( January 2007-May 2009 ) , all patients with NSCLC scheduled for surgery in our unit had a preoperative FDG-positron emission tomography (PET)/computed tomography ( CT ) in our institution , after a dedicated chest CT ( n=259 ) . Only patients with both FDG-PET/CT and negative dedicated chest CT scan ( N1 and N2 nodes < 1 cm ) were prospect ively included ( n=125 ) . Patients with cN1/cN2/cN3 and patients who had undergone preoperative chemo-radiotherapy were excluded . No invasive surgical staging was carried out in this group and curative resection plus systematic mediastinal dissection was performed except in the event of unexpected oncological contraindication . All variables were collected prospect ively and , when pathological information was obtained , all the cases were carefully review ed . RESULTS Mediastinal assessment by FDG-PET/CT  , negative predictive value ( NPV ) was 85.6 % , confidence interval ( CI ) : [ 77 - 91 ] ; false negatives ( FNs ) for mediastinal lymph nodes involvement was 14.4 % ( 18 cases ) . The pN2 stations most frequently involved were : 4R ( six cases ) , seven ( six cases ) and five ( five cases ) . Multiple-level pN2 occurred in six ( 4.8 % ) cases . Occult ( pN2 ) lymph nodes were more frequent in women ( p<0.01 ) , adenocarcinoma ( p<0.05 ) and pN1 ( p<0.05 ) . Pathological N2 prevalence for pN1 was 34 ( 27.7 % ) . Considering pathological staging as the gold st and ard , the agreement was 70 % and 47.5 % for stage IA and IB ( Kappa 's index : 0.72 and 0.76 ) and , in all patients , 47 % ( Kappa 's index : 0.27 ) . In general , down-staging is more frequent than up-staging . CONCLUSIONS Mediastinal staging of NSCLC by FDG-PET/CT showed a considerable incidence of FNs . NPV is lower than previously reported and the preoperative mediastinal staging by 18FDG-PET/CT may jeopardise the accurate treatment for early stage NSCLC patients BACKGROUND Correctly staging lung cancer is important because the treatment options and prognosis differ significantly by stage . Several noninvasive imaging studies and invasive tests are available . Underst and ing the accuracy , advantages , and disadvantages of the available methods for staging non-small cell lung cancer is critical to decision-making . METHODS Test accuracies for the available staging studies were up date d from the second iteration of the American College of Chest Physicians Lung Cancer Guidelines . Systematic search es of the MEDLINE data base were performed up to June 2012 with the inclusion of selected meta-analyses , practice guidelines , and review s. Study design s and results are summarized in evidence tables . RESULTS The sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were approximately 55 % and 81 % , respectively , confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis . For PET scanning , estimates of sensitivity and specificity for identifying mediastinal metastasis were approximately 77 % and 86 % , respectively . These findings demonstrate that PET scanning is more accurate than CT scanning , but tissue biopsy is still required to confirm PET scan findings . The needle techniques endobronchial ultrasound-needle aspiration , endoscopic ultrasound-needle aspiration , and combined endobronchial ultrasound/endoscopic ultrasound-needle aspiration have sensitivities of approximately 89 % , 89 % , and 91 % , respectively . In direct comparison with surgical staging , needle techniques have emerged as the best first diagnostic tools to obtain tissue . Based on r and omized controlled trials , PET or PET-CT scanning is recommended for staging and to detect unsuspected metastatic disease and avoid noncurative resections . CONCLUSIONS Since the last iteration of the staging guidelines , PET scanning has assumed a more prominent role both in its use prior to surgery and when evaluating for metastatic disease . Minimally invasive needle techniques to stage the mediastinum have become increasingly accepted and are the tests of first choice to confirm mediastinal disease in accessible lymph node stations . If negative , these needle techniques should be followed by surgical biopsy . All abnormal scans should be confirmed by tissue biopsy ( by whatever method is available ) to ensure accurate staging . Evidence suggests that more complete staging improves patient outcomes BACKGROUND Patients with clinical N1 ( cN1 ) lung cancer based on imaging are at risk for malignant mediastinal nodal involvement ( N2 disease ) . Endosonography with a needle technique is suggested over surgical staging as a best first test for preoperative invasive mediastinal staging . The addition of a confirmatory mediastinoscopy seems question able in patients with a normal mediastinum on imaging . This prospect i ve multicenter trial investigated the sensitivity of preoperative linear endosonography and mediastinoscopy for mediastinal nodal staging of cN1 lung cancer . METHODS Consecutive patients with operable and resectable cN1 non-small cell lung cancer underwent a  lobe-specific mediastinal nodal staging by endosonography . The primary study outcome was sensitivity to detect N2 disease . The secondary end points were the prevalence of N2 disease , the negative predictive value ( NPV ) of both endosonography and endosonography with confirmatory mediastinoscopy , and the number of patients needed to detect one additional N2 disease with mediastinoscopy . RESULTS Of the 100 patients with cN1 on imaging , 24 patients were diagnosed with N2 disease . Invasive mediastinal nodal staging with endosonography alone has a sensitivity of 38 % , which can be increased to 73 % by adding a mediastinoscopy . NPV was 81 % and 91 % , respectively . Ten mediastinoscopies are needed to detect one additional N2 disease missed by endosonography . CONCLUSIONS Endosonography alone has an unsatisfactory sensitivity to detect mediastinal nodal metastasis in cN1 lung cancer , and the addition of a confirmatory mediastinoscopy is of added value . TRIAL REGISTRY Clinical Trials.gov ; No. : NCT01456429 ; URL : www . clinical trials.gov RATIONALE Data regarding the sensitivity of endobronchial ultrasound-guided transbronchial needle aspiration ( EBUS-TBNA ) for staging of lung cancer in patients with radiographic N0 disease is scant and inconsistent . With increasing use of nonoperative ablative therapies , studies focusing on the performance characteristics of EBUS-TBNA in this population are important . OBJECTIVES To evaluate the sensitivity and negative predictive value ( NPV ) of EBUS-TBNA in patients with non-small cell lung cancer and radiographic N0 disease both by computed tomography ( CT ) and positron emission tomography (PET)-CT .  METHODS This was a retrospective review of EBUS-TBNA performed for lung cancer staging at two major academic centers from 2009 to 2014 . Patients with radiographic N0 disease ( lymph nodes [LN]≤1 cm in the short axis and maximum st and ardized uptake value≤2.5 by PET-CT ) were included . Primary outcome was sensitivity and NPV of EBUS-TBNA . MEASUREMENTS AND MAIN RESULTS Two hundred twenty patients with radiographic N0 disease underwent EBUS-TBNA , and 734 LN were sample d ( median 3 , range 1 - 6 ) . Median LN diameter was 0.72 cm . One hundred patients ( 45.5 % ) underwent surgery , and 120 patients ( 54.5 % ) had nonsurgical therapy . N status was up-staged in 49 patients ( 22.3 % ) : 18 by EBUS-TBNA ( N1=11 , N2=6 , N3=1 ) , 27 by surgery ( N1 intralobar=16 , N1 extralobar=3 , N2=8 [ 5 LN in stations 4 and 7 , and 3 LN in stations 5 - 6 ) , and 4 by imaging follow-up ( N1=2 , N2=2 ) . Overall false-negative rate of EBUS was 14.1 % ( sensitivity , 36.7 % ; specificity , 100 % ; and NPV , 84.7 % ) . False-negative rate was 27 and 3.3 % in surgical and nonsurgical population s , respectively . Excluding patients with occult disease " outside " the reach of EBUS , the overall false-negative rate of EBUS-TBNA was 5.5 % ( sensitivity , 60 % ; specificity , 100 % ; and NPV , 93.4 % ) . CONCLUSIONS This is the largest report of EBUS-TBNA in patients with N0 disease by " integrated " PET-CT . The majority of false-negative EBUS results were in LN stations outside its reach . In our study , both sensitivity and NPV of EBUS-TBNA were lower than early reports despite more extensive LN sampling . Given the high false-negative rate of imaging modalities , EBUS-TBNA may still play an important role in patients with radiographic N0 disease , particularly when nonsurgical ablative therapies are planned . Prospect i ve studies are needed to corroborate our findings in the nonsurgical population OBJECTIVE The role of combined endobronchial ultrasound-guided transbronchial needle aspiration ( EBUS-TBNA ) and endoscopic ultrasound-guided fine needle aspiration ( EUS-FNA ) with a single bronchoscope is poorly understood . The purpose of the present study was to eluci date the roles of EBUS-TBNA and EUS-FNA with a single bronchoscope in the preoperative hilar and mediastinal staging of non-small cell lung cancer ( NSCLC ) . METHODS A total of 150 patients with potentially resectable known or suspected NSCLC were enrolled in our prospect i ve study . EBUS-TBNA was performed , followed by EUS-FNA , with an EBUS bronchoscope for N2 and N3 nodes≥5 mm in the shortest diameter on ultrasound images , in a single session . RESULTS EBUS-TBNA was performed for 257 lymph nodes and EUS-FNA for 176 lymph nodes . Of the 150 patients , 146 had a final diagnosis of NSCLC . Of these 146 patients , 33 ( 23 % ) had N2 and /or N3 nodal metastases . The sensitivity of EBUS-TBNA , EUS-FNA , and the combined approach per patient was 52 % , 45 % , and 73 % , respectively ( EBUS-TBNA vs the combined approach , P=.016 , McNemar 's test ) . The corresponding negative predictive value was 88 % , 86 % , and 93 % . Two patients ( 1 % ) developed severe cough from EBUS-TBNA . CONCLUSIONS The combined endoscopic approach with EBUS-TBNA and EUS- 
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Conclusion : Preoperative systematic staging by EBUS-TBNA of early lung cancer can reduce postoperative upstaging .
Sensitivity for detection of radiologically occult mediastinal metastases seems lower than selective sampling of pathologic lymph nodes .