CYP1A1 and lung cancer: In the joint analysis of multiple SNPs stratified by smoking (Supplemental Table S2), the cumulative number of variants of all 8 SNPs from CYP1A1 and CYP1A2 in the chr15q24.1 region conferred a significant overall risk for lung cancer in ever smokers (OR = 1.03, 95%CI = 1.00–1.07, ptrend = 0.040) and a borderline protective effect in never smokers (OR = 0.91, 95%CI = 0.84–0.99, ptrend = 0.055).