Abstract: Colon cancer is a common malignant tumor of the digestive system, and the prognosis for patients with advanced-stage disease remains unsatisfactory. Transcatheter arterial chemoembolization (TACE) combined with targeted immunotherapy represents a crucial treatment approach for such patients. TACE can enhance tumor infiltration by T-lymphocyte subsets, activate effector CD4⁺ T cells to regulate immune balance within the tumor microenvironment, and mediate the binding of programmed death receptor-1 (PD-1)/programmed death ligand 1(PD-L1), thereby inhibiting the reactivity of CD8⁺ T cells and facilitating tumor immune escape. As dynamic indicators of systemic immune status, peripheral blood T-lymphocyte subsets play a pivotal regulatory role in the onset, progression, and therapeutic response of colon cancer, demonstrating potential value in predicting the efficacy of TACE combined with immunotherapy.This article systematically elucidated the molecular and cellular mechanisms of peripheral blood T-lymphocyte subsets in tumor immune escape in colon cancer and reviews their application prospects as non-invasive biomarkers for evaluating the efficacy of TACE and guiding individualized immunotherapy decisions. The aim is to provide immunological evidence and translational directions for optimizing multimodal treatment strategies for colon cancer.