title: T1 lung cancer on CT: frequency of extrathoracic metastases.
abstract: OBJECTIVE
  To determine the frequency of extrathoracic metastases in T1 non-small-cell lung cancer.
  
  
  METHODS
  Ninety patients with T1 lung cancer identified on CT were included. Extrathoracic metastases were evaluated at the time of initial diagnosis and during a 1-year follow-up study. The frequency of metastases was compared in terms of cell type (squamous or nonsquamous), size (<2 cm or >2 cm), and the initial CT findings of the tumor.
  
  
  RESULTS
  Extrathoracic metastases were identified in 12 (13%) of 90 patients at the time of diagnosis and in 10 patients at the 1-year follow-up study (total, 22 of 90 [24%] patients). Tumors with ground-glass opacity on CT were associated with a significantly lower prevalence of metastases (p = 0.042). The area of ground-glass opacity was seen in 1 of 13 (85%) patients with bronchioloalveolar carcinoma and in 12 of 53 (23%) patients with adenocarcinoma other than bronchioloalveolar carcinoma (p < 0.001). There was no significant difference in the prevalence of metastases between squamous and nonsquamous cell carcinoma, between tumors smaller than 2 cm (n = 17) and larger than 2 cm in diameter (n = 73) and between tumors with or without mediastinal nodal metastases (p>0.05).
  
  
  CONCLUSIONS
  Extrathoracic metastases were apparent at the initial examination in 13% of patients and at the 1-year follow-up examination in 11% of patients. The prevalence is significantly lower in tumors with ground-glass opacity.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: K J
authors.initials: KJ
authors.lastname: Jung
authors.forename: K S
authors.initials: KS
authors.lastname: Lee
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.forename: O J
authors.initials: OJ
authors.lastname: Kwon
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: Y M
authors.initials: YM
authors.lastname: Shim
authors.forename: T S
authors.initials: TS
authors.lastname: Kim
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000556:secondary*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015995:Prevalence; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed