Most cancer deaths are not caused by the original tumor, but by the cells that escape it — a process called metastasis that has long resisted full scientific explanation. Researchers at the University of Western Australia have built a three-dimensional synthetic tissue model that allows them, for the first time, to observe how the physical architecture of a tumor's surroundings — its stiffness, its gaps, its pathways — shapes whether cancer cells stay or begin to wander. The finding quietly shifts a long-held assumption: that metastasis is driven primarily by genetics and chemistry, when the b