Model-based CART analysis based on the biomarker AFP conditional on the tree analysis using GP73, AAT, Kininogen and age, after controlling for site, for the stratified male-only subset. Once again, age alone plays a significant role in the incidence of HCC (p < 0.001). The node pair (1,7) represents the sub-group of 42 men aged >61 that have a significantly higher incidence of HCC. This is consistent with the finding based on the gender-adjusted model shown in Figure 5. For men 61 years of age or younger, a higher level of GP73 (>6.3) is significantly associated with increased HCC incidence (p < 0.001) independent of AFP and AAT levels. The node pair (2,6) represents this sub-group of 49 men. A detailed interpretation of this tree is provided in the text.