EML4 and adenocarcinoma: When all of the eligible studies were pooled into the meta-analysis (Fig.3), no significant heterogeneity was observed (I2 = 18%, P = 0.25), thus we chose the fixed-effects model and found that a significantly higher EML4-ALK fusion gene positivity rate was associated with adenocarcinomas (pooled OR = 2.53, 95% CI = 1.66–3.86, P<0.0001).