While SHAP did not list it among R0’s top 3 features (due to the overwhelming influence of Stage/CA125), its clinical significance is unambiguous: CD28+CD4+ T cells drive T cell activation and cytokine secretion (e.g., IL-2, IFN-γ) that supports anti-tumor immunity, and their high expression correlates with lower residual risk. Here, CD4 is linked to neoplasm.