Cancer Systems Biology is now accepted and recognized as a promising field both in biological and clinical research. It relies on a rigorous formalization of regulation networks into precise and unambiguous languages. It provides both detailed and modular views of the complex biological system of interest (which in cancer research is typically an interaction network governing essential cellular events such as proliferation, differentiation, cell death...) in order to facilitate the interpretation of molecular profiles of tumors. The translation of these networks into mathematical models allows prediction of the evolution of the system in time and under certain perturbations. As a result, it can not only propose specific target points for pharmaceutical purposes, but also anticipate the evolution of tumors as well as their classifications. These characteristics emphasize the important role of Systems Biology of Cancer in the future of biomedical research.