RESUMEN
The combination of programmed death receptor 1 (PD-1) and its ligand 1 (PD-L1) can inhibit and deplete T lymphocyte function, thereby inducing immune tolerance, enabling tumor cells to escape the attack of immune cells and promoting the growth and metastasis of tumors. At the same time, the high expression of PD-1/PD-L1 can enhance metastatic ability of tumors and lead to increased mortality, and the treatment of inhibiting PD-1/PD-L1 signaling pathway has been proved effective in many tumors. However, the traditional treatment methods are limited for the treatment of colorectal metastatic cancer. The emergence of immunotherapy may bring new breakthroughs for the treatment of colorectal metastatic cancer. This article reviews the characteristics of expressions of PD-1/PD-L1 in colorectal metastases.