Principles

Oxford American handbook of oncology. Second Edition. Oxford University Press (2015)


  • The strongest evidence that early detection of cancer increases the chance of cure comes from randomized trials of cancer screening.
  • This has led to public awareness campaigns to persuade individuals to seek advice regarding suspicious symptoms at an early stage.
  • Unfortunately, most symptoms of cancer are symptoms of more advanced disease, and there is no evidence that encouraging early self-referral improves survival.
  • The screening of asymptomatic individuals to detect a cancer that has yet to declare itself clearly holds more promise.
  • For this to be effective in a population, there are certain criteria that should be met by the cancer in question, the screening test, and the screening program.

The cancer

  • Its natural history should be well understood.
  • It should be recognizable at an early stage.
  • Treatment at an early stage of disease should be more effective and improve outcomes compared to that at a later stage.
  • It should be sufficiently common in the target population to warrant screening.

The test

  • It should be sensitive and specific.
    • Sensitivity is the proportion of individuals with the disease who have a positive test.
    • Specificity is the proportion of individuals without the disease who have a negative test.
  • It should be reasonably acceptable.
  • It must be safe.
  • Ideally, it should be inexpensive.

The program

  • There must be adequate facilities for diagnosis in those with a positive test.
  • There should be effective treatment for screen-detected disease.
  • Repeated screening should be feasible at intervals if the disease is of insidious onset.
  • The benefit must outweigh the immediate and long-term physical and psychological harm.
  • The benefit should justify the cost.
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