Publication bias was evaluated by Begg's funnel plots and Egger's test (the allelic contrast of pooled analysis: Egger's test, P=0.656; Begg's test, P=0.592), and the P value of Egger's test and Begg's test were all more than 0.05, suggesting that there was no publication bias for the association between IL-4 rs2243250 variant and the susceptibility of smoking-related cancer in these included studies (Table 2 and Figure 5). Here, IL4 is linked to cancer.