Neutrophils are among the most abundant immune cell types in the tumour microenvironment and have been associated with poor outcomes across multiple cancer types. Yet despite mounting evidence of their role in tumour progression, therapeutic strategies targeting neutrophils have only recently gained attention and remain limited in scope. This is probably due to the increasing number of distinct neutrophil subtypes identified in cancer and the limited understanding of the mechanisms by which these subsets influence tumour progression and immune evasion. In this Review, we discuss the spectrum of neutrophil subtypes - including those with antitumour activity - and their potential to polarize towards tumour-suppressive phenotypes. We explore the molecular pathways and effector functions by which neutrophils modulate cancer progression, with an emphasis on identifying tractable therapeutic targets. Finally, we examine emerging clinical trials aimed at modulating neutrophil lineages and consider their implications for patient outcomes.