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Neutrophils are the predominant leucocytes in the blood and act as the first line of host defence against invading pathogens. Neutrophils have also been shown to play important roles in the other pathological conditions, including cancer. In the past decade, many efforts have been made to clarify the roles of neutrophils in cancer development and progression. It appears that neutrophils have both antitumour and protumour functions.1 On one hand, neutrophils can directly kill tumour cells by releasing antimicrobial and cytotoxic contents that are prestored in their granules. Neutrophils can induce apoptosis in tumour cells and reduce tumour growth when administrated into tumour-bearing animals. Neutrophils are regarded as important effector cells for monoclonal antibody (mAb)-mediated immunotherapy, where they interact with mAb through the Fc receptor, leading to antibody-dependent cell cytotoxicity. Neutrophils also have antimetastatic activity. In mouse models of cancer metastasis, neutrophils at the premetastatic site produce cytotoxic substances to eliminate tumour cells and limit their metastatic spread. In addition, neutrophils are able to regulate the activation of T cells and other immune cells to elicit antitumour immune responses. On the other hand, emerging evidence suggests that neutrophils possess protumour properties including the induction of malignant transformation, enhancement of tumour growth, establishment of premetastatic niche, stimulation of angiogenesis and promotion of immune evasion by suppression of innate and adaptive immune cells (eg, T cells and NK cells). The dual roles of neutrophils in cancer might be explained by their plasticity and the existence of distinct neutrophil subsets with differing properties within the tumours, which could be driven by signals from the tumours.2 ,3 In particular, neutrophils seem to have both stimulatory and suppressive roles in T-cell immunity. During the early phase of tumour growth, neutrophils tend to inhibit primary tumour growth by recruiting and activating CD8+ T …