Adverse events. Screening tests are medical procedures; thus, they carry
some risk. However, the chance that an adverse event will occur during a
screening test recommended by the U.S. Preventive Services Task Force
(USPSTF) or a professional society is low.
Anxiety. Screening individuals who are not at high risk of disease can cause
unnecessary anxiety during the waiting period for the test results.
False-positive test results. Not all individuals who have a positive screening
test result have the screened cancer. The rates of false-positive test results
vary depending on the test but are generally low; a false-positive screen can
result in additional unnecessary medical procedures, treatments, and anxiety.
False-negative test results. Not all individuals who have a negative screening
test result are free from the screened cancer. The rates of false-negative
test results are generally low, but a false-negative screen can lead to missed
opportunities for early treatment.
Overdiagnosis and overtreatment. Not all precancers or cancers detected
by screening will go on to cause symptoms and threaten life. Overdiagnosis,
as this is called, can lead to overtreatment, which may carry its own risks and
costs. The rates of overdiagnosis and overtreatment vary among screening
tests and are difficult to quantify.
BENEFITS OF SCREENING
Reduced cancer incidence. Screening tests can detect precancerous
lesions. Removal of the lesions can reduce, or even eliminate, an individual’s
risk of developing the screened cancer at that spot (see Figure 8, p. 39).
Reduced incidence of advanced disease. Screening tests that detect
developing cancers can reduce the individual’s risk of being diagnosed with
the screened cancer at a stage when it has spread to other parts of the body
(see Figure 8, p. 39).
Reduced cancer mortality. Diagnosis at an early stage of disease can
increase the likelihood that a patient can be successfully treated, which
thereby reduces the individual’s risk of dying from the screened cancer.
POTENTIAL RISKS OF SCREENING
Adapted from ( 1)