Cancer is a disease that is widely feared because of its prevalence and incidence, its widespread causes (heredity, environment, lifestyle) and the belief that 'everything causes cancer'. We review evidence on knowledge of cancer and find that knowledge is very limited. Then we examine factors that are related to knowledge of cancer and the pursuit of additional knowledge about cancer and factors that are related to health care behavior such as low rates of participation in cancer screening tests. This review leads us to conceptualize the essential, and perhaps central, role that fear of cancer has in the psychology of cancer. We then explore why cancer and fear of cancer have gained much attention in communities located near hazardous waste sites.