Abstract:

Objective To investigate the correlation between the combination of smoking and the polymorphisms of cytochrome P450（CYP） 1A1-MspⅠ and glutathione S-transferase（GST） T1 genes and oral cancer. Methods The genetic polymorphisms of CYP1A1-MspⅠ and GSTT1 were detected by polymerase chain reaction（PCR） technique in peripheral blood leukocytes of 300 oral cancer cases and 300 non-cancer controls, and the correlation between smoking, the two metabolic enzymes genetic polymorphisms and oral cancer were analyzed. Results The frequencies of CYP1A1-MspⅠ（m2/m2） and GSTT1（-） were 38.33% and 69.33% in oral cancer cases and 21.00% and 44.33% in healthy controls respectively. Statistical tests showed significant difference in the frequencies between the two groups （P<0.01）. The risk of oral cancer with CYP1A1-MspⅠ（m2/m2） was significantly higher than that of controls（OR= 2.34, 95%CI 1.76-4.07）. The individuals who carried with GSTT1（-） had a high risk of oral cancer（OR=2.84, 95% CI 1.98-4.54）. Combined analysis of the polymorphisms showed that percentage of CYP1A1-MspⅠ（m2/m2)/GSTT1（-）in oral cancer and control groups was 30.67% and 6.67% respectively（P<0.01）. The people who carried with CYP1A1-MspⅠ（m2/m2）/GSTT1（-） had a high risk of oral cancer（OR=8.27, 95%CI 3.63-11.29）. The smoking rate of the case group was significantly higher than that in the control group（OR=2.71, 95%CI 1.31-4.52, P<0.01）, and statistic analysis suggested an interaction between smoking and CYP1A1-MspⅠ（m2/m2）/GSTT1（-） genotypes polymorphisms which increased risk of oral cancer（OR=25.00, 95%CI 11.87- 35.64）. Conclusion CYP1A1-MspⅠ（m2/m2） and GSTT1（-）are the risk factors in oral cancer． Smoking is also related to the susceptibility to oral cancer. There may be a synergetic interaction among CYP1A1-MspⅠ（m2/m2）, GSTT1（-） and smoking on the elevated susceptibility of oral cancer.

Key words: oral cancer, cytochrome P450 1A1-MspⅠ, glutathione S-transferase T1, polymorphism, smoking