CD4 and neoplasm: Sensitivity analysis confirmed the robustness of the primary outcomes—including tumor weight and volume, survival time, metastatic nodules, immune organ indices (thymus and spleen), T-cell subset frequencies (CD4+/CD8+), and key cytokines (IL-12, IFN-γ, TNF-α, IL-10, and IL-2)—as the iterative exclusion of individual studies did not materially affect pooled effect sizes or heterogeneity patterns.