Previous studies reported that the polymorphisms of DNA repair genes, especially those in DNA excision repair pathways involving in the restoration of DNA adducts after exposure to UV light or benzo[a]pyren ediol epoxide (BPDE, a metabolite of benzo[a]pyrene), have observably linked with the occurrence and development of lung cancer.8, 9, 10, 11ERCC1 (excision repair cross‐complementation group 1), OGG1 (8‐oxoguanine DNA glycosylase), and MLH3 (mutL homolog 3) are three key rate‐limiting enzymes involving in NER, BER, and MMR pathways, respectively. This evidence concerns the gene MLH3 and lung carcinoma.