Highlight: microfluidic devices for cancer metastasis studies.

Whilst cancer is the single most researched disease by number of clinical trials, it remains a leading cause of death in middle- to high-income countries, with metastasis as the prime factor in cancer-associated mortality. The complex, multistep process of metastasis, in which cancer cells disseminate from the primary tumour and home to distant sites, is modulated by an extensive set of factors such as matrix properties, cancer cell plasticity, intercellular communication and oxygen tension. However, traditional treatment approaches have been focussed on the removal of the primary and secondary lesions, rather than interference with the metastatic cascade. Microfluidic platforms enable the deconvolution of the processes involved in metastasis by recapitulating key aspects of the tumour microenvironment in a controlled and reproducible fashion. Herein, we review recent developments in microfluidics for metastasis research and explain how these devices offer exceptional potential towards gaining a deeper understanding of this key aspect of malignancy.