The Pienta laboratory focuses on gaining insight into the biologic mechanisms underlying prostate cancer metastasis. These insights have been used to identify novel targets for the treatment of advanced prostate cancer, thus successfully moving bench research into the clinic in the form of phase II and phase III clinical trials. Currently, the Pienta lab operates under the hypothesis that there is an opportunity to devise new cancer therapies based on the recognition that tumors have properties of ecological systems. There has been an increasing recognition that the tumor microenvironment contains host non-cancer cells in addition to cancer cells, interacting in a dynamic fashion over time. The cancer cells compete and/or cooperate with nontumor cells, and the cancer cells may compete and/or cooperate with each other. The interaction of these cancer and host cells to remodel the normal host organ microenvironment may best be conceptualized as an evolving ecosystem. We have used microdevices to help design ecosystems to mimic organ niches, such as bone marrow, to which cancer cells metastasize. Describing tumors as these ecological systems defines new opportunities for novel cancer therapies.