This cluster of papers focuses on the role of cancer stem cells, epithelial-mesenchymal transition, and the tumor microenvironment in tumor metastasis, drug resistance, and cell plasticity. It explores the identification, regulation, and behavior of cancer stem cells, as well as their interactions with the microenvironment and implications for metastatic colonization. Additionally, it delves into the use of organoid models to study cancer stem cells and tumor progression.