Cancer can sometimes be detected in asymptomatic patients via regular physical examinations and screening tests. (See also Overview of Cancer Overview of Cancer Cancer is an unregulated proliferation of cells. Its prominent properties are A lack of differentiation of cells Local invasion of adjoining tissue Metastasis, which is spread to distant sites... read more .)
Physical examinations for cancers of the thyroid, oral cavity, skin, lymph nodes, testes, prostate, cervix, and ovaries should be a part of routine medical care.
Screening tests Screening Tests Test results may help make a diagnosis in symptomatic patients (diagnostic testing) or identify occult disease in asymptomatic patients (screening). If the tests were appropriately ordered on... read more are tests that are done in asymptomatic patients at risk. The rationale is that early diagnosis may decrease cancer mortality by detecting cancer at an early and curable stage. Early detection may allow for less radical therapy and reduce costs. Risks include false-positive results, which necessitate confirmatory tests (eg, biopsy, endoscopy) that can lead to anxiety, significant morbidity, and significant costs; and false-negative results, which may give a mistaken sense of security, causing patients to ignore subsequent symptoms.
Screening for cancer should be done in the following circumstances:
Recommended screening schedules are constantly evolving based on ongoing studies (see table Screening Procedures in Average-Risk Asymptomatic People as Recommended by the American Cancer Society (ACS), US Preventive Services Task Force (USPSTF), and American College of Physicians (ACP) Screening Procedures in Average-Risk* Asymptomatic People as Recommended by the American Cancer Society (ACS), US Preventive Services Task Force (USPSTF), and American College of Physicians (ACP)† Cancer can sometimes be detected in asymptomatic patients via regular physical examinations and screening tests. (See also Overview of Cancer.) Physical examinations for cancers of the thyroid... read more ). Current considerations regarding screening include the developing understanding that some findings (particularly in prostate and breast tissues) that appear cancerous may not actually progress to cancer within a person's remaining lifetime. For example, routine screening for blood levels of prostate-specific antigen (PSA) in men and routine screening mammograms in women may result in biopsy findings that a pathologist considers a cancer but that will not manifest clinically as a cancer or that manifest as a cancer that does not adversely affect survival. In such cases, people may receive cancer treatments (eg, surgery, chemotherapy, radiation therapy) that do not benefit them.
The key issue in screening is how many people need to be screened to prevent one cancer death and how many people will receive unnecessary interventions or be given unnecessary concern. Because of these complexities, there is considerable controversy regarding who should be screened and at what ages for what cancers. Recommendations from the American Cancer Society (ACS), the US Preventive Services Task Force (USPSTF), and various subspecialty organizations may differ. The American College of Physicians (ACP) offers recommendations based on a review of existing guidelines and the evidence they include for breast cancer and colon cancer screening.