Screening and technology

Screening programmes involve the testing of healthy subjects in order to find early disease at a stage when total cure is more likely than in cases left to present with symptoms. There is more to screening than meets the eye-it is not always the intuitively simple solution to disease prevention that it can appear to be. Techniques available for performing screening tests are advancing yet, for many proposed screening programmes, there is little clarity about the significance of abnormalities that will be detected, or whether those who are screened will actually be helped. The author´s greatest experience with screening is with cervix cancer. Even this well organised programme has proved difficult to evaluate and still has inherent problems with over-diagnosis. The problems and possibilities of screening for disease are discussed using examples from several existing and proposed screening activities