Assessment of the potential association between glutathione S-transferase polymorphisms and colorectal cancer: A systematic review, meta- and pooled analysis

Background. Colorectal cancer is the second leading cause of death from cancer in Canada. Many studies have examined associations between GSTM1, GSTT1, and GSTP1 polymorphisms and colorectal cancer but with conflicting results. The objective of this study was to examine the totality of evidence for association between these polymorphisms and risk for colorectal cancer or adenoma. Methods. A systematic review, meta- and pooled analysis were conducted. Results. The meta- and pooled analysis suggest weak significant associations between GSTM1 (ORpooled=1.11; 95%CI: 1.02,1.23), GSTT1 (ORpooled=1.22; 95%CI: 1.10,1.35), and with presence of null variants of each and colorectal cancer, but with heterogeneity between studies. No association between GSTP1 and colorectal cancer, or between any of the polymorphisms and colorectal adenoma, was observed. Significant multiplicative GST gene-gene interactions or gene-environment (smoking) interaction effects were not observed. Conclusion. Evidence to date shows weak associations between GSTM1 and GSTT1 and colorectal cancer