PER2 and cancer: Low expressions of Per1 and Per2 were related to poor OS in patients with cancers (Per1: HR=1.35, 95%CI: 1.06∼1.72, P=0.014 and Per2: HR =1.43, 95%CI: 1.10∼1.85, P=0.007), with high observed heterogeneity (Per1: Ι2=77.1%, P<0.001 and Per2: Ι2=63.1%, P=0.006) (Table 4 and Fig 5).