People are offered screening tests throughout their lifetime, from birth through to old age. But although screening for certain diseases/disorders is widely accepted, screening for other types remains controversial. The aim of this chapter is to provide a general outline of the current debates and developments within screening, and it draws principally on examples from the field of cancer screening. More detailed discussion of the issues surrounding cardiac, genetic and antenatal screening and further discussion of cancer screening, can be found in other chapters in this book (see ‘Screening: antenatal’, ‘Screening: cancer’, ‘Screening: cardiac’ and ‘Screening: genetic’).

The aims of screening

The term ‘screening’ is usually reserved to describe the testing of all people within a specific sector of the population (e.g. people within a particular age range) who have no symptoms, and who appear to be at ‘average risk’ of getting the target disease. Although, in the case of neonates, screening might be used to enhance the medical management of the future date (i.e. once the child has been born) or to give parents the opportunity to terminate a pregnancy if they do not wish to have a child who has a particular disability or condition, the main purpose of screening is often to reduce disease-related morbidity and mortality by detecting disease at an early stage, when treatment is more likely to be successful.

Early detection can lead to fewer disease-related complications, because simpler, less toxic treatment is required. It can also dramatically enhance a person's chance of survival.