ALK and non-small cell lung carcinoma: NSCLC patients with ALK rearrangements tended to be younger than those without (WMD: −7.16 years; 95% CI: −9.35 to −4.96; P<0.00001), and this tendency was persisted in Asians (WMD: −6.99; 95% CI: −8.91 to −5.08; P<0.00001) and Caucasians (WMD: −6.18, 95% CI: −15.13 to 2.77; P = 0.18), albeit strong evidence of heterogeneity (Figure 2).