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

## TL;DR

This review explores how immune cells in the tumor environment affect colorectal cancer and highlights new immunotherapy approaches.

## Contribution

The paper provides a comprehensive overview of immune cell roles in CRC and emerging cell-based therapies.

## Key findings

- Immune cells in the tumor microenvironment can either suppress or promote colorectal cancer growth.
- Immune-checkpoint blockade shows promise, particularly in microsatellite instability-high tumors.
- Emerging cell-based immunotherapies may improve precision treatment for colorectal cancer.

## Abstract

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.