Studying cancer metastasis: Existing models, challenges and future perspectives

Cancer metastasis causes most cancer-related deaths. Several model systems to study the complex and multi step process of metastasis exist, including in vitro systems, ex-vivo organ slices, Drosophila Melanogaster and zebrafish models and the use of the chorio allantoic membrane (CAM) of fertilized chicken eggs. These models are relatively easy and cheap but often lack the opportunity to study the complete metastasis cascade. More complex but also more expensive is the use of animal models including the more recently developed patient derived tumor xenografts (PDTX). In this review, we give an overview of the existing metastatic models, discuss the challenges of improving current models to enhance translation from the preclinical to the clinical setting and consider future perspectives.