AFP and hepatocellular carcinoma: Interestingly, low SOD2 expression is also associated with shorter OS and RFS in subgroups of patients characteristic of less advanced disease, including low AFP concentration (< 400 ng/μl) (Fig. 5c), no tumor embolus (Fig. 5d), no liver cirrhosis (Fig. 5e), high differentiation (Grade I+II) (Fig. 5f) and complete tumor capsule (p = 0.035) subgroup, suggesting that SOD2 is involved in the development and progression of HCC during early disease stages.