title: Low-dose computed tomography screening for lung cancer in a general population: characteristics of cancer in non-smokers versus smokers.
abstract: OBJECTIVE
  To report the detection rate for lung cancers in computed tomography (CT) screening in Japanese adults, and to analyze differences in the appearance of the cancers in non-smokers versus smokers.
  
  
  METHODS
  Subjects consisted of 7,847 Japanese adults who received low-dose CT screening at least once in a 3-year period. The detection rate of lung cancers and the correlation of imaging, clinical, and pathologic findings of cancers in non-smokers versus smokers were examined.
  
  
  RESULTS
  The detection rate for lung cancer was 1.1% for both non-smokers (45 of 4,251) and smokers (39 of 3,596). The prevalence of well-differentiated adenocarcinomas was greater in non-smokers (88%; 22 of 25) than in smokers (29%; 4 of 14) (P < .001). The prevalence and incidence of pathologic stage IA disease were greater in non-smokers than in smokers (92%; [22 of 24] vs 58% [7 of 12], and 100% [19 of 19] vs 70% [14 of 20]) (both P < .05). The mean size of the tumors in the non-smokers (12.4 mm) was smaller than that in smokers (18.2 mm) (P < .001). The percentage of cancers categorized as pure or mixed ground-glass opacity (86%; 38 of 44) on CT was greater in non-smokers than in smokers (46%; 16 of 35) (P < .001).
  
  
  CONCLUSIONS
  Most of the lung cancers in non-smokers were slow-growing adenocarcinomas appearing as faint ground-glass opacities on CT, whereas rapidly growing cancers appearing as solid nodules were more commonly seen in smokers.
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000453:epidemiology; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D015995:Prevalence; D011829:Radiation Dosage; D012907:Smoking / Q000453:epidemiology*; D014057:Tomography, X-Ray Computed / Q000379:methods*