Identification and surveillance of individuals at high risk

Inherent in any cancer detection program strategy is the identification and surveillance of groups at especially high risk, in that success can be expected to be highest and costs for positive case finding lowest. The epidemiologic concepts of sensitivity and specificity are of importance in such programs. Among occupational groups, directed programs have started to demonstrate usefulness in altering outcome. For other types of exposure, some results have been disappointing, such as x-ray screening among heavy smokers, but other programs, such as DES exposure, promise to be of value. As new modalities for early detection become available, new concerns about screening will arise, though clearly prevention is still the optimal strategy.