The role of neutrophils in cancer

Introduction: It has been known for some time that neutrophils are present in the tumour microenvironment; but only recently have their roles been explored. Sources of data: Comprehensive literature search of neutrophils and cancer (PubMed, Google Scholar and CrossRef) for key articles (systematic reviews, meta-analyses, primary research). References from these articles crosschecked for additional relevant studies. Areas of agreement: Neutrophils are a heterogeneous population with both pro- and antitumour roles, and display plasticity. Several neutrophil subpopulations have been identified; defined by a combination of features (density, maturity, surface markers, morphology and anatomical site). Areas of controversy: Limitations in translating murine tumour models to human pathology, and paucity of human data. Consensus in defining human neutrophil subpopulations. Growing points: Neutrophils as therapeutic targets and as possible playmakers in the biological response to newer targeted cancer drugs. Areas timely for developing research: Understanding the metabolic programming of neutrophils in the tumour microenvironment.