The goal of screening for cancer is to detect preclinical disease in healthy, asymptomatic patients to prevent adverse outcomes, improve survival, and avoid the need for more intensive treatments. Screening tests have both benefits (eg, improved health outcomes) and adverse consequences (eg, cost, anxiety, inconvenience, false-positive results, and other test-specific harms such as overdiagnosis and overtreatment).
Breast self-examination, breast self-awareness, clinical breast examination, and mammography all have been used alone or in combination to screen for breast cancer. In general, more intensive screening detects more disease. Screening intensity can be increased by combining multiple screening methods, extending screening over a wider age range, or repeating the screening test more frequently.
However, more frequent use of the same screening test typically is associated with diminishing returns (ie, repeating the test twice as often does not make it twice as effective) and an increased rate of screening-related harms.
Determining the appropriate combination of screening methods, the age to start screening, the age to stop screening, and how frequently to repeat the screening tests require finding the appropriate balance of benefits and harms. Determining this balance can be difficult because some issues, particularly the importance of harms, are subjective and valued differently from patient to patient. This balance can depend on other factors, particularly the characteristics of the screening tests in different populations and at different ages.
