Differences in clinical presentation of non-small cell lung cancer in never-smokers versus smokers

Objectives: 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.