Cancer is a leading cause of morbidity and mortality worldwide. The process of metastasis involves many steps, with circulating tumour cells (CTCs) playing an essential role. This literature review examines the role of neutrophil extracellular traps (NETs) in the survival and implantation of CTCs in secondary organs. CTCs get to secondary organs primarily through the bloodstream and can then extravasate into the parenchyma of these organs. NETs are formed by various stimuli, including cancer. They can occur in primary tumours, but are most commonly present in metastatic tumour sites. They make the blood vessels of both primary organs and secondary organs more permeable, allowing CTCs to enter the bloodstream and extravasate from the bloodstream into the secondary organs, respectively. NETs also protect CTCs from degradation by the immune system and can trap CTCs in the microvasculature of secondary organs, allowing CTCs to be more numerous in the vasculature before entering these organs. This contributes to the formation of micrometastases and, subsequently, macrometastases. It also appears that this metastatic cascade is more easily initiated after surgery of the primary tumour, due to an increase in inflammation and, thus, increased formation of NETs. NETs can also awaken dormant tumour cells, which promotes metastasis as well. In short, NETs play an important role in the different stages of the life cycle of CTCs. Treatments against NETs may, therefore, offer important advances in fighting cancer.

(BELG J MED ONCOL 2023;17(4):112–7)