Three‑dimensional models to study breast cancer (Review).

Breast cancer (BC) is the most commonly occurring cancer and primary cause of cancer‑related mortality in women worldwide. Investigations into BC have been conducted in in vitro and in vivo models. Of these models, the cultivation of tumor cell lines in two‑dimensional models is the most widely employed in vitro model to study tumor physiology. However, this approach does not accurately model all aspects observed in tumors. To address these limitations, three‑dimensional (3D) in vitro models have been developed. In these, it is possible to reproduce the interaction between tumor cells and the extracellular matrix, as well as the interrelationship between tumor cells and stromal cells, in order to replicate the interactions observed within the 3D environment of in vivo tumors. The present review summarizes the most common 3D in vitro models used to study BC, including spheroid models, organ‑on‑a‑chip models, hydrogel models and bio‑printed models, with a discussion of their particular advantages and limitations.