Adult 1 Carcinogenesis 1 Case-Control Studies 1 DNA Methylation 1 DNA Repair 1 DNA methylation 1 DNA repair 1 DNA repair protein XRCC1 1 Epigenomics 1 Humans 1 MLH3 protein, human 1 MRE11 Homologue Protein 1 MRE11A protein, human 1 Male 1 Methylation 1 Mismatch Repair Endonuclease PMS2 1 Mouth Mucosa 1 Mouth Neoplasms 1 MutL Proteins 1 Oral mucosa 1 PMS2 protein, human 1 Real-Time Polymerase Chain Reaction 1 Repair gene 1 Smokers 1 Smoking 1 X-ray Repair Cross Complementing Protein 1 adult 1 case control study 1 double strand break repair protein MRE11 1 epigenetics 1