Advances in 3D Bioprinting for Breast Cancer Modeling: Tumor Microenvironment, Metastasis, and Drug Screening.

The tumor microenvironment (TME) is a complex and heterogeneous milieu encompassing biological and biochemical events and diverse physical, chemical, and mechanical interactions between tumor and stromal cells. This heterogeneity plays a pivotal role in regulating tumor progression, metastasis, and resistance to therapy. In breast cancer, cancer-associated fibroblasts, adipocytes, endothelial cells, and immune cells all contribute to this intricate environment, necessitating precise spatial and cellular modeling to better replicate physiological conditions. Moreover, angiogenesis and metastasis are key contributors to breast cancer mortality. Therefore, three-dimensional (3D) models that incorporate co-cultures of cancer and stromal cells are essential for recreating realistic TMEs. This review highlights the advances in 3D bioprinting technologies for modeling the breast cancer TME. We discuss their potential in drug screening, explore their advantages and limitations, and outline future directions to enhance their fidelity and translational relevance.