Explore the complex dynamics of cancer metastasis in this 41-minute lecture from the International Centre for Theoretical Sciences' discussion meeting on mathematical and statistical approaches to disease modeling. Delve into the stages of cancer progression, focusing on metastasis as the primary cause of cancer-related deaths. Examine the traits cells need to metastasize successfully and question whether genetics alone can explain cancer development. Investigate the potential of a 'systems' approach to understanding cancer, with particular emphasis on the EMT/MET process as the engine of metastasis. Learn about the hybrid E/M phenotype, its stability, and its role in forming circulating tumor cell clusters. Analyze the crosstalk between EMT and Notch pathways, and understand why hybrid E/M cells are clinically significant. Conclude with ongoing questions in the field and a broader perspective on cellular plasticity in cancer progression.