Polymorphisms of CYP1A1 and GSTM1 genes and susceptibility to oral cancer

Purpose: Oral cancer is the fifth most common form of cancer in the world and comprises 6.5% of all cancer deaths. Since one of the major risk factors for oral cancer is tobacco use, we hypothesized that polymorphic genes coding for tobacco carcinogen-metabolizing enzymes may play a role in oral cancer susceptibility. Materials and Methods: To investigate the association between polymorphisms of the CYP1A1 and GSTM1 genes and risks for oral squamous cell carcinoma (OSCC) in the Korean population, the prevalence of the CYP1A1 Mspl and GSTM1 null polymorphisms were examined in 72 patients with histologically confirmed primary OSCC, as well as in 221 healthy control subjects. Results: A significant risk increase for oral cancer was observed among subjects with the homozygous CYP1A1 (m2/m2) genotype (OR = 3.8, 95% CI = 1.9-7.7), but not the GSTM1 null genotype (OR = 0.7, 95% CI = 0.4-1.3). Risk for oral cancer was significantly increased in subjects with the homozygous CYP1A1 (m2/m2) genotype, regardless of smoking history (smokers; OR = 4.4; 95% CI = 1.2-16.3; non-smokers OR = 4.9; 95% CI = 1.9-12.5). Using the potentially most protective genotype GSTM1 (+)/ CYP1A1 [(m1/m1)+ (m1/m2)] as the reference group, an increased risk for oral cancer was observed among subjects with the GSTM1 (+)/CYP1A1 (m2/ m2) (OR = 2.0, 95% CI=0.8-5.2), and GSTM1 (-)/ CYP1A1 (m2/m2) (OR = 4.9, 95% CI = 1.5-15.5) genotypes (p <0.009, (x² trend test). Conclusion: Our results suggest that individuals with a genotype of CYP1A1 (m2/m2) and GSTM1 (-) are highly susceptible for OSCC and that the CYP1A1 (m2/m2) genotype is closely associated with increased risk of OSCC in Koreans.