Fig. 1

Associations between dental status, substance use, and incident lung cancer, overall and stratified by cigarette smoking and opium use status. Subjects were stratified into binary groups of those that ever smoked cigarettes or used opium and those that never used either cigarettes or opium. DMFT, the sum of decayed, missing, or filled teeth; HR, hazard ratio; T, tertile. HRs for cigarette, opium, and nass use are from the model including DMFT. In the stratified analysis of ever users of cigarettes/opium, the reference group for cigarette pack-years included subjects that never smoked cigarettes but used opium, and vice versa for the opium use reference group. Full results, including associations with sociodemographic factors, can be found in Tables S1 and S2. *P < 0.05