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 cross-checked 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.