The second leading cause of death in the USA is cancer. Institutions worldwide are devoting significant resources to the treatment of cancer, and the elucidation of the disease pathway. While great progress has been made in understanding and treating carcinogenesis, many aspects of the disease remain intractable. Throughout the history of science many other disciplines--astronomy, particle physics, etc.--have been advanced when the fundamental ideas governing the discipline were redefined. These redefinitions are often termed 'paradigm shifts'. The new sciences of chaos theory and complexity have led to paradigm shifts in many unrelated disciplines such as economics, meteorology and seismology. Our current understanding of carcinogenesis has resulted from a conventional view of the disease process. In this perception, the mutation of a gene, or several genes, leads to cancer. Applying the formalism of chaos theory and complexity to carcinogenesis, however, leads to a different perception of the disease. If we look closer, cancer can be viewed as a complex adaptive system. Redefining our perception of cancer may lead to a deeper understanding of the disease, and possibly result in novel methods of therapeutic intervention.