Can the functioning of human society be compared to the functioning of tumors in the human body? How do tumors come about? Why are we so interested in them? What can we learn from them? In this book, the multicellular organism is presented as a complex system consisting of multiple cells working together, while tumors arise from the abandonment of cooperation and violate the basic principles necessary to maintain a healthy body. Based on General Systems Theory, the author traces parallels with, and extrapolations from, the rules of cooperation and their potential corruption in other complex systems as well, including human society. In addition to a detailed introduction of the basics of tumor formation and development, the book offers reflections on the question of whether human beings, like tumor cells, tend to corrupt in dangerous and self-destructive ways the most important rules for the healthy functioning of the social system to which they belong.