Tumor Associated Neutrophils. Their Role in Tumorigenesis, Metastasis, Prognosis and Therapy

Tumor Associated Neutrophils (TANs) are recruited to the tumor microenvironment by cytokines and chemokines, can be classified according to their activation and cytokine status and effects on tumor cell growth in N1 and N2 TANs. N1 TANs exert an antitumor activity, by direct or indirect cytotoxicity. On the other hand, N2 TANs promote immunosuppression, tumor growth, angiogenesis and metastasis by DNA instability, or by cytokines and chemokines release. In tumor patients, either a high number of TANs and Neutrophil-to-Lynphocyte Ratio (NLR) do correlate with poor prognosis, and, so far, TAN counts and NLR can be regarded as biomarkers. Due to the key role of TANs in promoting tumor progression, therapeutic…