RRM2 and cancer: High expression of RRM2 was significantly correlated with age (p = 0.006), clinical stage (p = 1.30e-05), T classification (p = 7.37e-04), M classification (p = 0.017), N classification (p = 1.15e-05), cancer status (p = 5.51e-04), new tumor event after initial treatment (p = 0.043), and smoking status (p = 1.81e-06), as shown in Figure 2.