Cancer screening

Cancer screening is a complicated science. Each screening intervention must be carefully assessed before it is widely implemented. A screening test can falsely appear useful as it finds disease at an early stage and leads to intervention and cure. Such a test can be harmful to the population screened if it commonly finds disease that fulfills the pathologic criteria of cancer but behaves indolently (meaning it would never harm the host). Such "pseudo-disease" or "overdiagnosed disease" has been demonstrated in many malignancies including cancers of the lung, breast, and especially the prostate. The nature of each specific screening test and each disease is such that some screened patients may receive unnecessary treatment with all its complications and risk. Alternatively, some screening technologies have been proven useful providing net benefit to the population screened. Often these beneficial technologies are underused. These screening technologies if widely implemented have the potential of saving countless lives. Many available screening tests have tremendous potential in terms of benefit, but have yet to be fully assessed. At the minimum, patients should be informed of what is known, what is not known, and what is believed about these tests.