*comparison of squamous vs. non-squamous cell carcinoma **(ORs 2.09; 95% CI, 1.06∼4.14, p< 0.05) by multivariate logistic regression test NSCLC: non-small cell lung cancer, BSC: best supportive care,
Definition of abbreviations: Adeno Ca = adenocarcinoma Mean and standard deviation (SD) were calculated. †p-values calculated using Student's t-test or Fisher exact test. ‡Missing pack-years for 1 sub
