title: Occult mediastinal lymph node metastasis in NSCLC patients diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT: Risk factors, pattern, and histopathological study.
abstract: BACKGROUND
  Integrated F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is widely used for mediastinal lymph node (MLN) staging in patients with non-small cell lung cancer (NSCLC). However, FDG-PET/CT has certain limitations. Prediction of occult MLN metastasis could allow selection of candidates for preoperative cervical mediastinoscopy or endobronchial ultrasound-guided transbronchial needle aspiration. This study defined risk factors for occult MLN metastasis in patients with NSCLC patients who were diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT.
  
  
  METHODS
  Consecutive patients with NSCLC who underwent staging using integrated FDG-PET/CT as an adjunct to CT prior to lung resection from October 2006 to September 2009 were evaluated retrospectively. The prevalence of MLN metastasis in patients diagnosed as clinical N0-1 was analyzed according to clinicopathological factors such as tumor location, tumor size, histology, and FDG uptake by the primary tumor. Risk factors for occult MLN metastasis were defined by multivariate analysis. Patterns of occult MLN metastasis were also analyzed and the involved MLNs were further examined histopathologically.
  
  
  RESULTS
  The incidence of MLN metastasis was 11% (24 patients of 224). Multivariate analysis identified adenocarcinoma (P=0.04), tumors located in upper or middle lobe (P=0.02), tumor size >3 cm (P=0.01), and SUV(max) of primary tumor >4.0 g/ml (P=0.04) as significant risk factors for MLN metastasis. The pattern of occult MLN metastasis was typical for NSCLC cases. The size of metastatic foci were small, with 68% of foci smaller than 4.0mm.
  
  
  CONCLUSIONS
  The present study demonstrated that adenocarcinoma, tumors located in the upper or middle lobe, tumor size >3 cm, and SUV(max) of primary tumor >4.0 g/ml are risk factors for occult MLN metastasis in patients with NSCLC who were diagnosed as clinical N0-1 by preoperative integrated FDG-PET/CT and CT. Patients with tumors located in the right upper or middle lobe are considered candidates for cervical mediastinoscopy because the involved metastatic mediastinal lymph nodes are easily accessible by these modalities.
authors.affiliation: Department of Thoracic Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, Osaka 537-8511, Japan. rkanzaki@tj8.so-net.ne.jp
authors.forename: Ryu
authors.initials: R
authors.lastname: Kanzaki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Higashiyama
authors.forename: Ayako
authors.initials: A
authors.lastname: Fujiwara
authors.forename: Toshiteru
authors.initials: T
authors.lastname: Tokunaga
authors.forename: Jun
authors.initials: J
authors.lastname: Maeda
authors.forename: Jiro
authors.initials: J
authors.lastname: Okami
authors.forename: Takenori
authors.initials: T
authors.lastname: Kozuka
authors.forename: Takuya
authors.initials: T
authors.lastname: Hosoki
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Motohisa
authors.initials: M
authors.lastname: Takami
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tomita
authors.forename: Ken
authors.initials: K
authors.lastname: Kodama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D015994:Incidence; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000473:pathology; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18