Association Between GSTM 1 Polymorphism and Nasopharyngeal Cancer Susceptibility : a Meta-analysis

Nasopharyngeal cancer (NPC) is one of the most common otolaryngological cancers, characterized by a high frequency of nodal and distant metastasis at diagnosis (Chan, 2011). Although it is rare in many areas of the world, NPC still causes serious damage to public health (Chan, 2011). The exact pathogenesis of NPC has not yet been understood up till now. Apart from epstein-barr virus (EBV) infection and endogenous/exogenous carcinogens, genetic susceptibility seems to be a risk factor playing an crucial role in the development of NPC (O’Neil et al., 2008). Many published studies have revealed that polymorphisms of carcinogen-metabolizing genes encoding detoxifying enzymes contribute to the variation of individual susceptibility to NPC (Chang et al., 2006; Guo et al., 2008; Zhuo et al., 2009). Glutathione S-transferase M1 (GSTM1) is a detoxifying enzyme, which plays a critical role in the detoxification of varieties of carcinogenic metabolites (Moaven et al., 2010). Genetic variation of GSTM1 results in loss of its enzymatic activity and consequently affects an