association of gstm1 and gstt1 null deletions and gstp1 rs1695 polymorphism with the risk of hepatocellular carcinoma: a systematic review and meta-analysis

Context: hepatocellular carcinoma (hcc), as the most common type of primary liver cancer (accounting for 70% -90% of all liver cancers), is the seventh most common malignancy worldwide. glutathione s-transferases (gsts) are a specific group of enzymes that are responsible for the detoxification of carcinogens. according to the available literature, genetic variations in this group of enzymes may be associated with the risk of hcc. in this study, we aimed to assess the association of gstm1 and gstt1 null deletions and gstp1 rs1695 polymorphism with the risk of hcc. methods: we systematically searched electronic databases, including pubmed, scopus, and web of science, using appropriate keywords to gather relevant data until march 2019. studies that met the inclusion criteria were included in the meta-analysis, using either fixed or random-effects models based on the presence of heterogeneity. results: this meta-analysis pooled 19 studies for gstm1 null deletions, 14 studies for gstt1 null deletions, and five studies for gstp1 rs1695 polymorphism. in terms of heterogeneity, the pooled odds ratio (or) was calculated in a random-effects model for both asian and non-asian populations. hcc was found to be associated with gstm1 null deletions (or = 1.26, 95% ci: 1.00 -1.58, p = 0.05) and gstt1 null deletions (or = 1.39, 95% ci: 1.10 -1.74, p = 0.005); however, no significant association was found between hcc and gstp1 rs1695 polymorphism (or = 1.14, 95% ci: 0.86 -1.50, p = 0.36). conclusions: we found that gstm1 and gstt1 null deletions increased the risk of hcc; however, the gstp1 rs1695 polymorphism did not have a similar effect.