Recent advances in molecular cell biology, immunology, and toxicology enhance detection of actual and incipient disease and the definition of risk. Tumor-associated antigens may greatly improve detection of low-grade tumor cells. Several new strategies depend upon detecting molecular lesions of the genes controlling cell growth (oncogenes) at either the gene or protein levels. Highly sensitive techniques detecting DNA adducts are refining the ability to detect specific DNA damage shortly after exposure. The recognition of controls that actively stop proliferation (tumor suppressor genes), regulate differentiation or of relationships between metabolism and carcinogenesis may lead to new ways to identify persons genetically at increased risk from carcinogenic exposure. Current technologies, those on the near horizon, and long-term research needs are analyzed critically in terms of screening objectives.