Key immune cells in the tumor immune microenvironment of colorectal cancer: Roles and research advances (Review)

Colorectal cancer (CRC) is the third most common cancer globally and the second leading cause of cancer-related mortalities.Surgery-centered multimodal therapy remains the cornerstone of care, yet outcomes are poor in advanced or drug-resistant disease.The tumor immune microenvironment (TIME), a network of immune cells, cytokines and stromal elements, shapes antitumor immunity and can either restrain or encourage tumor growth.Specific immune cells within the TIME influence CRC biology, while immune-checkpoint blockade has delivered notable benefits, especially in microsatellite instability-high tumors.The present review discusses the principal immune cell populations in the CRC TIME, outlines their mechanisms of action and discusses emerging cell-based immunotherapies that may guide future precision treatment.Contents 1. Introduction 2. Tumor-associated macrophages (TAMs) 3. T cells 4. B cells 5. NK cells 6. DCs 7. Neutrophils 8. Application of multi-omics technologies in CRC TIME 9. Limitations and challenges in translating TIME-targeted therapies to CRC 10.