Cancer is one of the most frequent of the mortal disease. In the modern industrialized world the incidence of cancer continues to rise. There are various reasons for this, for example the keeping of statistics on cancer has been improved, the risk of getting cancer is elevated due to the increase in life expectancy, and there has been a rise in the effects of environmental cancerogens on man. This text presents a brief overview of understandings of the development of cancer. It aims to make clear mainly the biological roots of carcinogenesis and presents a concept of five basic programmes for cell control - division, growth, differentiation, function and apoptosis. Each of these cell programmes is characterized according to the interaction of the cell's genes, signals and metabolites. An understanding of the regulatory processes in normal cells allows profound insights into those of cancer cells. The findings on cancer development are then integrated into a general framework, a unified holistic theory of evolution. Against this background, approaches to cancer diagnosis, prophylaxis and therapy are discussed.