Why are only some conditions screened for?

The World Health Organisation outlined 10 principles for a National Screening Programme. The UK’s Cancer Screening Programmes are based on them:

• The condition being screened for should be an important health problem.
• How the condition progresses should be well understood.
• Early stages of the condition/disease should be recognisable.
• Treatment of the condition/disease at an early stage should be more beneficial than if the condition was treated at a later stage.
• There is a suitable test.
• This test should be acceptable to the population.
• There are adequate facilities for the diagnosis and treatment of abnormalities detected.
• For a condition of a gradual onset, screening is carried out at repeated intervals determined by the natural progression of the condition.
• The chance of causing physical or psychological harm to those screened should be less than the chance of benefit.
• The cost of a screening programme is balanced against the benefit it provides.

Source: Wilson and Junger, 1968, WHO.