The theory of biological robustness and its implication in cancer.

One of the essential issues in systems biology is to identify fundamental principles that govern living organisms at the system level. In this chapter, I argue that robustness is a fundamental feature of living systems where its relationship with evolution-trade-offs among robustness, fragility, resource demands, and performance-provides a possible framework for how biological systems have evolved and been organized. In addition, diseases can be con- sidered as a manifestation of fragility of the system. In some cases, such as cancer, the disease state establishes its own robustness against therapeutic interventions. Understanding robustness and its intrinsic properties will provide us with a more profound understanding of biological systems, their anomalies, and countermeasures.