Behavior of seeds and soil in the mechanism of metastasis: a deeper understanding.

The so-called "seed and soil" hypothesis proposed by Stephen Paget in 1889 to explain the metastatic behavior of cancer cells and the homing of certain cancers to "selected" sites has been a well-recognized phenomenon for over a century. What advances have been made to increase our understanding of this phenomenon and what does it really implicate in terms of targets for therapy?