Pharmacologic interventions to prevent the evolution of human cancers are still in its infancy, although a good number o- mostly controlled - clinical studies have been performed in the past two decades. However, regarding the partially stagnating therapeutic results of major epithelial cancer types such as breast-, lung-, colon- and ENT-cancer types, the problem of in terference with the evolution of disease at a preclinical level is an intriguing one, and the field seems to develop into one of the fastest growing domaines of modern oncology. This process is fa cilitated by the developments of molecular on co-genetics and the gowing existence of family cancer units, allowing to better identi fy and inform respective high risk groups, thus enabling re searchers and clinicians to more realistically target their chemo preventive efforts to the true populations at risk. On this changing background, the newly formed International Society of Cancer Chemoprevention (ISCaC) together with the Swiss Cancer League and the Interdisciplinary Oncology Center of St. Gallen/Switzerland organized an international Symposium in September 1997, inviting basic researchers, epidemiologists and clinical oncologists of related disciplines to discuss pertinent issues of experimental and clinical chemo- and bio-prevention in a scientific workshop.