Resection or ablation for very early hepatocellular carcinoma and the fundamental problem of causal inference

Despite strict size definition (single ≤2 cm), very early stage hepatocellular carcinoma (HCC) still represents an heterogeneous stage, regarding, in particular, liver function (i.e., Child-Pugh and MELD scores or bilirubin levels and presence or absence of portal hypertension), tumor location (deep in the liver, adjacent to major biliary or vascular structures or located on the surface of the liver) and patient characteristics (i.e., age, absence or presence of comorbidities as well as patient treatment preference).