EMT and cancer: what clinicians should know

Cell plasticity is a crucial trait for cancer progression towards metastasis and treatment resistance. Research efforts from the past 20-30 years have revealed that the dynamic flux of the epithelial-mesenchymal transition (EMT) programme is one of the major underlying processes enabling cancer cell plasticity and greatly facilitates these major causes of cancer mortality. The spectrum of evidence ranges from extensive data from cell line and animal model studies across multiple cancer types through a rapidly expanding body of work demonstrating associations between EMT biomarkers and disease progression and mortality in patients. EMT is also implicated in resistance to most of the major treatment modalities, yet our efforts to harness this knowledge to improve therapeutic outcomes are currently in their early stages. In this Review, we describe clinical evidence supporting a role of EMT and the associated epithelial-mesenchymal plasticity in various stages of cancer in patients and discuss the subsequent clinical opportunities and challenges associated with attempts to implement this knowledge as novel therapies or clinical management approaches.