TP53 and hepatocellular carcinoma: The pathogenesis, etiology, and classification of HCC evolved from its original HBV-associated HCC in 1981 to the role of HCV in 1989, the contribution of p53 mutation in 1996, the use of noninvasive criteria for definition and classification in early 2000, to the association of NASH and HCC in 2002-2003.