Biology of metastatic disease.

: Metastasis is highly organized and organ selective, a process involving multiple sequential steps. It occurs through complex interactions between tumor cells and the host. The surviving metastatic cells have heterogeneous biologic and antigenic or immunogenic properties, and the metastatic cells take over the homeostatic mechanisms of the host. Investigations at the genetic level are necessary to make advances in the early diagnosis, treatment, and prevention of metastatic disease.