Genetic polymorphisms and susceptibility to esophageal cancer among Chinese population (review)

Esophageal cancer, which is prevalent in China and some other parts of the world, is a complex disease likely resulting from polymorphisms of multiple interacting genes and gene-environment interactions. Recent efforts have been made to analyze the associations between risk of this cancer and hereditary sequence variations in genes involved in metabolism, DNA repair and cell cycle control. We summarized here the results of published case-control studies that have examined the effects of common alleles of 15 genes, MTHFR, CYP1A1, CYP2A6, CYP2E1, GSTM1, GSTT1, GSTP1, NAT2, XRCC1, XPD, hOGG1, MGMT, p53, CNDD1 and L-Myc, on risk of esophageal squamous cell carcinoma among Chinese. Statistically significant differences in genotype frequencies found in case-control comparisons were MTHFR C677T and A1298C polymorphisms, the XRCC1 Arg194Trp polymorphisms, the hOGG1 Ser326Cys polymorphism, and the p53 Arg72Pro polymorphism. The overall effects of these genetic polymorphisms were moderate in terms of relative risk, with ORs ranging from 2-10. There was also some evidence that genetic polymorphisms in certain carcinogen-metabolizing enzymes such as CYP2E1, CYP1A1, CYP2A6, GSTM1, and GSTP1 modulate risk of the cancer, although the results require confirmation with larger sample size studies. For polymorphisms in GSTT1, XPD, CCND1, and L-Myc, the risk estimate from the studies was sufficiently precise to exclude an OR >/=1.5.