“…1), 10 original articles satisfied our inclusion criteria (Hamajima et al, 2002;Sarbia et al, 2003;Zhang et al, 2003aZhang et al, , 2003bvon Rahden et al, 2005;Zhang et al, 2006;Zhou et al, 2006;di Martino et al, 2007;Feng et al, 2008;Marjani et al, 2010). We found that Sarbia et al (2003) had performed 3 studies that explored the association of the NQO1 gene 609 C > T polymorphism with EC risk (Zhang et al, 2003a;von Rahden et al, 2005). In view of the ethnical differences, the EC type (esophageal squamous cell cancer and esophageal adenocarcinoma), and cases enrollment, we regarded these three studies separately.…”