“…Eight eligible case-control studies associated with rs4778889 T/C polymorphism, seven for rs11556218 T/G polymorphism, and six for rs4072111 C/T polymorphism. The studies focused on the following cancer types: 2 studies investigated colorectal carcinoma (Gao et al, 2009b;Azimzadeh et al, 2011), 2 nasopharyngeal carcinoma (Gao et al, 2009a;Qin et al, 2014), 1 gastric cancer (Gao et al, 2009b), 1 hepatocellular carcinoma (Li et al, 2011), 1 renal cell carcinoma (Zhu et al, 2010) and 1 cervical cancer (Zhao et al, 2012). All of the study designs were hospital based (HB) and used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) genotyping method.…”