“…Three articles were excluded because of a lack of usable data. Eventually, a total of 23 eligible studies involving 14,409 cases and 16,996 controls were included in the pooled analyses (Chen et al, 2004;Zhang et al, 2005;Koushik et al, 2006;Hazra et al, 2007;Lissowska et al, 2007;Moore et al, 2007;van den Donk et al, 2007;Wang et al, 2007;Xu et al, 2007;Yu et al, 2007;Guerreiro et al, 2008;Steck et al, 2008;Stevens et al, 2008;Bentley et al, 2010;Komlosi et al, 2010;Vainer et al, 2010;Curtin et al, 2011;Mohammad et al, 2011;Naushad et al, 2011Naushad et al, , 2012Weiner et al, 2012;Succi et al, 2014;Wu et al, 2014). The characteristics of the studies selected are summarized in Table 1.…”