Differences in non–small cell lung cancer (NSCLC) characteristics and outcomes in never-smokers versus ever-smokers. In both pathological stage I and stage II NSCLC, distribution of cancer differs, as does survival. Never-smokers with stage I cancer have better survival than ever-smokers, and never-smokers with stage II cancer have worse survival than ever-smokers. This may be partly related to the heterogeneity of cancer characteristics within pathological cancer stages, as well as to apparent differences in effect of risk factors for mortality and cancer recurrence, such as effect of tumor size and presence of positive lymph nodes in never-smokers versus ever-smokers.