OBJECTIVETo investigate the correlation between the combination of smoking and the polymorphisms of cytochrome P450 (CYP) 1A1-Msp I and glutathione S-transferase (GST) T1 genes and oral cancer.

METHODSThe genetic polymorphisms of CYP1A1-Msp I 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.

RESULTSThe frequencies of CYP1A1-Msp I (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-Msp I (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-Msp I (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-Msp I (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-Msp I (m2/m2)/GSTT1(-) genotypes polymorphisms which increased risk of oral cancer (OR=25.00, 95%CI 11.87-35.64).

CONCLUSIONCYP1A1-Msp I (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-Msp I (m2/m2), GSTT1(-) and smoking on the elevated susceptibility of oral cancer.