These guidelines are intended primarily for patients at average risk. They do not apply to symptomatic patients, who should be managed by the usual standards of medical practice. Patients considered to be at elevated risk because of family history or environmental exposures should seek a physician's recommendations for establishing an appropriate early detection program. Data are incomplete regarding the costs, risks, and benefits of cancer screening in the general population. Few large, randomized studies have been completed for specific cancers, such as breast cancer.
Data are scanty and uncertain for younger and older women.
To be useful, a screening test must detect preclinical cancers that are less likely to be lethal after treatment than if allowed to progress to the point of usual clinical detection. False positive screening test results lead to unnecessary workups and treatment for indolent tumors and increase medical, psychological, and financial costs. Identifying high-risk populations through risk evaluation, including genetic testing, can help channel scarce resources to susceptible persons. However, because of the lack of convincing evidence of benefit from screening for lung cancer, periodic chest x-rays and sputum cytology are not recommended. PSA is being increasingly used for prostate cancer detection.