title: Diagnostic accuracy of lymph node metastasis depends on metabolic activity of the primary lesion in thoracic squamous esophageal cancer.
abstract: The metabolic activity of the primary tumor is an important variable in (18)F-FDG PET interpretation for presurgical staging, because this activity is likely to affect the possibility of detection of malignant involvement in lymph nodes (LNs). The purpose of this study was to reevaluate the diagnostic accuracy of (18)F-FDG PET/CT for the presurgical staging of esophageal squamous cell carcinoma (SCC) in correlation with the (18)F-FDG avidity of the primary lesions.
  
  
  METHODS
  One hundred fifty-six patients (mean age ± SD, 61.4 ± 8.0 y) underwent (18)F-FDG PET/CT before surgical esophagectomy and LN dissection. LN metastasis was identified using the fusion of PET and CT images with increased (18)F-FDG uptake greater than the background activity of the adjacent structures. The results of the patients' (18)F-FDG PET/CT examinations for LN involvement were compared with the histopathologic results to investigate the diagnostic accuracy of (18)F-FDG PET/CT for tumor staging. In addition, we examined the correlation between the diagnostic accuracy of (18)F-FDG PET/CT for LN involvement and the (18)F-FDG avidity of the primary lesions, to investigate the effect of tumor aggressiveness on the diagnosis of LN metastasis.
  
  
  RESULTS
  The diagnostic accuracy of (18)F-FDG PET/CT for LN metastasis showed a low sensitivity, ranging from 29.3% to 53.3%, whereas the specificity was higher than 89.8% in regional thoracic nodes and in remote areas of the cervical and abdominal regions. The (18)F-FDG uptake of the primary lesions positively correlated with that of the metastatic LNs in the thoracic field (R = 0.52, P < 0.05). As a result, our receiver-operating-characteristic analyses demonstrated an area under the curve value of 0.73, with the optimal cutoff value at a maximum standardized uptake value of 3.3 in patients with mid to high (18)F-FDG avidity in the primary lesions (maximum standardized uptake value ≥ 5).
  
  
  CONCLUSIONS
  This study showed that the avidity of the primary esophageal SCCs affected the detectability of lymph nodal metastases. If primary lesions of esophageal SCC present with a low (18)F-FDG uptake, PET/CT may have a limited role for initial staging because of low sensitivity to detect lymph node metastases.
authors.affiliation: Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Manabe
authors.forename: Naoya
authors.initials: N
authors.lastname: Hattori
authors.forename: Kenji
authors.initials: K
authors.lastname: Hirata
authors.forename: Kazuo
authors.initials: K
authors.lastname: Itoh
authors.forename: Masao
authors.initials: M
authors.lastname: Hosokawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Noriko
authors.initials: N
authors.lastname: Oyama-Manabe
authors.forename: Nagara
authors.initials: N
authors.lastname: Tamaki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D018307:Neoplasms, Squamous Cell / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology* / Q000601:surgery; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013909:Thorax; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: FDG PET; esophageal cancer; pathology; squamous cell carcinoma