title: Differences in clinical presentation of non-small cell lung cancer in never-smokers versus smokers.
abstract: OBJECTIVE
  This study was conducted to evaluate whether or not tumor spread and the diagnostic process in non-small cell lung cancer (NSCLC) is different based on smoking history.
  
  
  METHODS
  Associations between smoking status and clinical presentation were evaluated controlling for the effect of histology. Lung cancer with delayed diagnosis (LCDD) and incidental detection (LCID) were determined based on medical records.
  
  
  RESULTS
  Of 914 patients, frequency of distant metastases was more common in never-smokers than in smokers (59% and 36%, respectively; P<0.001). Although never-smokers were more likely to have LCDD than smokers (18% and 11%, respectively; P=0.038), LCDD were not significantly associated with frequency of distant metastases [49% (LCDD) vs. 42% (non-LCDD); P=0.189] as well as tumor [29% (T3-4) vs. 24% (T1-2); P=0.134] and node [43% (N2-3) vs. 44% (N0-1); P=0.838] stage. Interestingly, never-smokers are more likely to have LCID than smokers (31% and 19%, respectively; P=0.010). In survival analysis, LCID (P=0.001; HR, 0.63) remained a prognostic factor, while LCDD did not.
  
  
  CONCLUSIONS
  This study suggests distinct metastatic pattern and diagnostic processes of never-smokers. The link between survival and incidental detection was also indicated.
authors.affiliation: Department of Internal Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, Seoul, Korea;
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Division of Hematology-Oncology, Department of Internal Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, Seoul, Korea;
authors.forename: Im Ii
authors.initials: II
authors.lastname: Na
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi-do, Korea;
authors.forename: Seung-Hun
authors.initials: SH
authors.lastname: Jang
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi-do, Korea;
authors.forename: Yong Il
authors.initials: YI
authors.lastname: Hwang
authors.affiliation: Department of Radiology, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, Seoul, Korea.
authors.forename: Du Hwan
authors.initials: du H
authors.lastname: Choe
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, Seoul, Korea.
authors.forename: Cheol Hyeon
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Thoracic Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological & Medical Sciences, Seoul, Korea.
authors.forename: Heejong
authors.initials: H
authors.lastname: Baek
keywords: Non-small cell lung cancer (NSCLC); advanced stage; incidental detection; smoking history