How can a screening programme be shown to provide benefit?

Compare complete strategies

Screening targets people without signs or symptoms of the cancer being sought. The intervention includes invitation, testing, diagnostic confirmation and access to care. Specify the population, interval and comparator, and track people who do not complete each step.

Avoid conclusions based on apparent survival

Earlier diagnosis can increase measured survival time without delaying death. Some detected tumours would never have caused problems during a person’s life. Earlier stages and additional diagnoses therefore cannot replace assessment of relevant outcomes and harms.

Present benefits and harms together

Look for absolute effects over the same follow-up period, false positives, procedures, overdiagnosis and unequal access. Compare programmes in similar populations and report participation. Expected benefit also depends on the ability to complete investigation and indicated treatment.

Interpretation limits

This content explains evidence assessment and does not set individual screening ages or intervals.

Overdiagnosis means detecting disease that would not cause problems; it is not the same as a false-positive test.

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Select tools by method, population and purpose. A thematic connection does not validate use in every case.