It is often suggested that the incidence of cancer and coronary heart disease could be much reduced or even eliminated if only people would stop smoking cigarettes and eat fewer high-cholesterol foods. The evidence, however, shows that such views are simplistic and unrealistic and that, instead, cancer and CHD are the product of many risk factors acting synergistically. Psychosocial factors (stress, personality) are six times as predictive as smoking, cholesterol level or blood pressure and much more responsive to prophylactic treatment. This book admits that, while smoking is a risk factor for cancer and CHD, its effects have been exaggerated. A more realistic appraisal of a very complex chain of events incorporating many diverse factors is given, and appropriate action to prevent cancer and coronary heart disease is discussed.