This case-control study aims to investigate the association of ten genetic variants-nine SNPs across five ALDH family genes and one SNP in ADH1B (rs1229984)-with the risk of lung cancer and its major subtypes. The primary hypothesis is that the ALDH2 rs671 variant is associated with the risk of lung cancer and its major subtypes. The secondary hypothesis is that other ALDH variants-including rs2228093 and rs2073478 in ALDH1B1, rs1127717 and rs2276724 in ALDH1L1, rs3741172, rs17856219, and rs77341916 in ALDH3B2, and rs3765310 in ALDH5A1-are also associated with lung cancer risk. Demographic and lifestyle covariates such as age, gender, ethnicity, smoking status, alcohol consumption, educational level, and case-control status will be incorporated into the analysis.