Tumor-associated neutrophils: a complex role in cancer

Neutrophils, constituting 50-70 % of circulating leukocytes, serve as first responders in innate immunity. In recent years, as research into the tumor immune microenvironment has intensified, the role of neutrophils in tumor has gained increasing attention. Studies have shown that neutrophils are involved in tumor growth, metastasis, angiogenesis, and immune regulation. However, because tumor-associated neutrophils (TANs) often exhibit dual-edged effects and significant heterogeneity, it remains challenging to determine whether they act as allies or adversaries. This review systematically summarizes the classification and functions of neutrophils in tumor. Additionally, the current challenges in tumor-associated neutrophils are discussed, aiming to provide new insights for the development of neutrophil-related immunotherapies.