The detection of cancer risk factors and their possible avoid ance would most effectively contribute to the fight against cancer. Research in these areas depends to a substantial degree on in vivo experimental animal models and on epide miologic studies, including data from cancer registries. When the Deutsches Krebsforschungszentrum was founded in 1964, its division "Mechanisms of Tumorigenesis" and a number of other divisions became engaged in research on chemical carcinogenesis of the skin, mainly using the mouse skin as an experimental model. Their interest orig inated in part from investigations of the new and at that time controversial pathogenic principle of conditional car cinogens as represented by certain tumor promoters which are per se noncarcinogenic. During the past 25 years, conditional carcinogens in terms of tumor promoters were established as anew, nonclassical category of cancer risk factors besides the classical solitary carcinogens. In the course of this exciting period, scientists of our center started cooperative programs with clinical dermato logists of the University of Heidelberg at the Clinics of Dermatology in Heidelberg and Mannheim, to extend the scope of their investigations into clinical oncology and to contribute by experimental approaches to solving problems in clinical oncology. This led to a gradual shift from mere animal studies to the more direct analyses of human tumors and opened up for us a new phase of research.

Infections must be thought as one of the most important, if not the most important, risk factors for cancer development in humans. Approximately 15-20% of all cases of cancer around the world are caused by viruses. The
establishment of a causal relationship between the presence of specific infective agents and certain types of human cancer represents a key step in the development of novel therapeutic and preventive strategies.
In this book, Professor zur Hausen (Nobel Prize in Physiology/Medicine 2008) provides a thorough and comprehensive overview on carcinogenic infective agents -- viruses, bacteria, parasites and protozoons -- as well as their corresponding transforming capacities and mechanisms. The result is an invaluable and instructive reference for all oncologists, microbiologists and molecular biologists working in the area of infections and cancer.
The author was among the first scientists to reveal the cervical cancer-inducing mechanisms of human papilloma viruses and isolated HPV16 and HPV18, and, as early as 1976, published the hypothesis that wart viruses
play a role in the development of this type of cancer.

Anlasslich des 25jahrigen Jubilaums des Deutschen Krebsforschungszentrums (DKFZ) in Heidelberg geben die Autoren einen Uberblick uber Institutionen und Organisationsformen der Krebsforschung in Deutschland, speziell der Vorgeschichte und Geschichte des DKFZ seit Anfang des 20. Jahrhunderts."