Modelling metastasis in a dish: in vitro approaches for studying breast cancer progression

Cancer metastasis, driven by cell migration, remains the leading cause of cancer-related deaths. In breast cancer, its high metastatic potential underscores the need for better preclinical models to bridge the gap between laboratory findings and clinical outcomes. However, studying migration in vitro remains challenging due to the complexity of tumour invasion and the difficulty of replicating physiologically relevant conditions. Traditional two-dimensional (2D) models, such as the scratch assay and transwell migration assay, offer simplicity and reproducibility but fail to capture the tumour microenvironment and dynamic migration behaviours. Advanced three-dimensional (3D) models, including spheroids, organoids, microfluidic systems, and organ-on-a-chip platforms, provide more physiologically relevant conditions but are often limited by cost and technical complexity. This mini-review provides an overview of widely used in vitro models for studying breast cancer migration and evaluates their respective advantages, limitations, and future potential. While no single system currently achieves the ideal balance between physiological relevance and practical accessibility, combining complementary tools remains the most effective strategy for investigating the metastatic cascade. Continued innovation in in vitro platforms is essential for improving translational accuracy and supporting the development of more effective anti-metastatic therapies.