Metastasis is the multistep process by which cancer cells spread from a primary tumor to distant organs, and it is responsible for most cancer deaths. Research shows that metastasis is not random: specific cancer types tend to colonize particular organs, shaped by both cancer cell traits and the “soil” of the target tissue.

A central focus is how cells break free from the primary tumor. They undergo changes in adhesion and shape, often through epithelial to mesenchymal transition, becoming more motile and invasive. They degrade the surrounding matrix, enter blood or lymphatic vessels, and must survive mechanical stress and immune attack while circulating.

Very few circulating tumor cells succeed in forming metastases. They must exit the vasculature at permissive sites, where local blood flow patterns, vessel structure, and inflammatory signals can trap or attract them. Once in a new organ, they face a foreign microenvironment. Many enter dormancy, surviving without forming detectable lesions until local signals, such as changes in immunity or stromal remodeling, allow them to resume growth.

Organ specificity is a major theme. Studies highlight how interactions with resident cells, extracellular matrix, and organ specific immune landscapes either support or block metastatic outgrowth. For instance, bone, lung, liver, and brain each present distinct selective pressures and supportive niches.

Current research targets multiple stages of this cascade. Approaches include blocking cell migration and intravasation, disrupting survival signals in circulation, making distant niches inhospitable, and awakening or eliminating dormant cells. Understanding these detailed mechanisms is guiding more precise strategies to prevent or treat metastatic disease.