title: Accurate molecular detection of non-small cell lung cancer metastases in mediastinal lymph nodes sampled by endoscopic ultrasound-guided needle aspiration.
abstract: OBJECTIVE
  The recurrence of disease after the complete resection of early stage non-small cell lung cancer (NSCLC) indicates that undetected metastases were present at the time of surgery. Quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) is a highly sensitive technique for detecting rare gene transcripts that may indicate the presence of cancer cells, and endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) is a minimally invasive technique for the nonoperative sampling of mediastinal lymph nodes. The aim of this study was to determine whether these two techniques could enhance the preoperative detection of occult metastases.
  
  
  METHODS
  Patients with NSCLC were evaluated with chest CT and positron emission tomography scans. Those patients without evidence of metastases (87 patients) underwent EUS-guided FNA. Lymph nodes from levels 2, 4, 5, 7, 8, and 9 were sampled and evaluated by standard cytopathology and real-time RT-PCR. Normal control FNA specimens were obtained from patients without cancer who were undergoing EUS for benign disease (17 control specimens). For each sample, messenger RNA was extracted and real-time RT-PCR was used to quantitate the expression of six lung cancer-associated genes (ie, CEA, CK19, KS1/4, lunx, muc1, and PDEF) relative to the expression of an internal control gene (beta(2)-microglobulin).
  
  
  RESULTS
  Clinical thresholds of marker positivity were set at 100% specificity, as determined by the receiver operating characteristic curve analysis. Of the cytology-positive lymph nodes (27 lymph nodes), the expression of the KS1/4 gene was above its respective clinical threshold in 25 of 27 samples (93%), making this the most sensitive marker for the detection of metastatic NSCLC. At least one of the six lung cancer-associated genes was overexpressed in 18 of 61 cytology-negative patients (30%), of which KS1/4 was overexpressed in 15 of 61 patients (25%).
  
  
  CONCLUSIONS
  Based on the high accuracy of EUS-guided FNA/RT-PCR, we predict that some of the patients in the cytology-negative/marker-positive category will have high NSCLC recurrence rates. Among the genes used in our marker panel, KS1/4 appears particularly useful for the detection of overt or occult metastatic disease.
authors.affiliation: Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224, USA. Wallace.michael@mayo.edu
authors.forename: Michael B
authors.initials: MB
authors.lastname: Wallace
authors.forename: Mark I
authors.initials: MI
authors.lastname: Block
authors.forename: William
authors.initials: W
authors.lastname: Gillanders
authors.forename: James
authors.initials: J
authors.lastname: Ravenel
authors.forename: Brenda J
authors.initials: BJ
authors.lastname: Hoffman
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Reed
authors.forename: Mostafa
authors.initials: M
authors.lastname: Fraig
authors.forename: David
authors.initials: D
authors.lastname: Cole
authors.forename: Michael
authors.initials: M
authors.lastname: Mitas
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D044963:Biopsy, Fine-Needle; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology*; D019160:Endosonography; D020869:Gene Expression Profiling; D006801:Humans; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology*; D049268:Positron-Emission Tomography; D012333:RNA, Messenger / Q000235:genetics; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D014157:Transcription Factors