SOD2 and liver cancer: Moreover, low expression of SOD2 is associated with multiple primary tumors (p = 0.012), tumor embolus (p = 0.016), tumor recurrence (p = 0.039), and advanced tumor stages as classified by the Primary Tumor, Lymph Nodes and Metastasis (TNM) (p = 0.006), and Barcelona clinic liver cancer (BCLC) (p = 0.001) staging systems.