The study of cancer has been transformed in recent years by including ecological thinking about the roles of heterogeneity, behavior, and eco-evolutionary feedbacks. Given the importance and interest of cancer as a complex system, more and more ecologists have brought their expertise to bear. But this intellectual progress has not been a one-way street. The insights into complex systems we have gained by harnessing the data revolution in cancer have much to offer to ecologists, particularly those seeking to link outcomes at the level of individual phenotypes with their underlying genetic and physiological mechanisms. Modern ecology links across size scales from the physiology within individuals to the behavior of whole organisms and their interactions in communities, and across time scales from rapid behavioral responses to deep evolutionary time. Cancer systems biology takes on the same issues, linking mechanisms at the gene and molecule level to the whole organism and its environment, and short-term cell responses to the phylogenies of metastatic tumors and the evolutionary history of their hosts. This session reaches across these many approaches, showing how the successes and failures of cancer biology in using vast quantities of data to understand and predict outcomes has begun to inform multiple fields of ecology: (1) the community ecology of diversity and the maintenance and role of heterogeneity in tumors, (2) the evolutionary ecology of life history and defensive tradeoffs, (3) metabolic and physiological ecology of tumors as consumers of space and resources, (4) the paleoecology of tumors and the consequences of their distinct modes of evolution. Cancer biologists have the advantage of being able to measure, in exquisite detail, the genetic and protein structure of individual cells and analyze with the full range of tools of bioinformatics. Ecologists generally lack the resources and tools to measure individuals with this resolution, but have the advantage of being able to visit and manipulate their living field site and have thus developed a set of experimental and modeling tools for understanding complex dynamics that far exceed those in cancer biology. These complementary skills point the way to a synthesis of ways to understand the complex ecology of self-organized systems, and this session will a chance for ecologists to take the lead in creating this synthesis and open new doors for unified ecological thinking.