Relationship between CYP1A1,GSTM1 and GSTT1 genetic polymorphisms and susceptibility of esophageal cancer in Wuwei,Gansu province

Objective To study the genetic polymorphisms of cytochrome P450(CYP1A1),glutathione S-transferase M1(GSTM1),glutathione S-transferase T1(GSTT1)and the susceptibility of esophageal cancer in Wuwei,Gansu province.Methods The study was conducted among 189 cases of esophageal cancer and 216 cases of normal controls.The genotypes of the GSTM1 and GSTT1 were detected by multiplex-PCR.Polymorphism of CYP1A1 was detected through PCR-based restriction fragment length polymorphisms(PCR-RFLP).Results The combined frequen- cies of T/C and C/C genotype of CYP1A1 in tumors and normal controls were 74.1%and 67.6%, respectively.The differences between patients and normal controls were not statistically significant. The frequencies of GSTM1 null genotype in tumor group(58.7%)were significantly higher than those in controls(41.2%)and this genotype may increase the susceptibility to esophageal cancer(P0.05).The frequency of GSTT1 null genotype in tumor group was 51.9%,while in controls it was 43.5%.The GSTT1 null genotype did not change the susceptibility to esophageal cancer.The incidence of GSTM1,GSTT1 combined null genotype in tumor group was 38.6%, while in controls it was 19.6%.This different percentage between patients and normal controls was statistically significant(P0.05).The CYP1A1 gene heterozygous mutation type or homozygous mutation type combined with GSTM1,GSTT1 null genotype increased the risk of esophageal cancer(OR 2.385,95%CI 1.094～3.495).Conclusion Both the variation of CYP1A1 gene or GSTT1 null genotype alone may not be related with the susceptibility to esophageal cancer but GSTM1 null genotype alone or combined with GSTT1 null genotype or the 3801 T-C variation of CYP1A1 gene are correlated with esophageal cancer.The results suggest that GSTM1 null genotype alone or in combination with other defective genotypes may serve as risk factors to the esophageal cancer.