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.
- 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.
- 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.
- 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.