Cancer can sometimes be detected in patients who do not have symptoms via regular physical examinations and screening tests. (See also Overview of Cancer.)
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 are tests that are done in patients who do not have symptoms but who are 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 adverse effects. 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:
When distinct high-risk groups can be identified such as people who have a family history of breast, ovarian, pancreatic, hematologic, colonic, or prostate cancers
When a screening test is proved to have a benefit that exceeds risk and is recommended by competent health authorities
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)). 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 males and routine screening mammograms in females 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 U. S. 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.
Screening Procedures in Average-Risk* Asymptomatic People as Recommended by the American Cancer Society (ACS), U. S. Preventive Services Task Force (USPSTF), and the American College of Physicians (ACP)†
Type of Cancer | Procedure | Frequency |
|---|---|---|
Breast cancer | Mammography | ACS: Recommended at the following ages:
USPSTF: Every 2 years for women ages 40 to 74 ACP: Recommended at the following ages:
|
Cervical cancer | Papanicolaou (Pap) test and/or human papillomavirus (HPV) test | ACS: Recommended at the following ages:
USPSTF: Recommended at the following ages:
|
Prostate cancer | Blood test for PSA (prostate-specific antigen) | ACS: Because the benefit of screening is uncertain, patient and physician should discuss the potential harms and benefits of prostate cancer screening beginning at age 50 (age 45 for African Americans or those who have a father or brother who had prostate cancer before age 65) USPSTF: The patient and physician should discuss the potential harms and benefits of prostate cancer screening beginning at age 55, but recommends against screening at age 70 or older. |
Colorectal cancer | Stool testing: Fecal immunochemical test (FIT), high-sensitivity guaiac fecal occult blood test (gFOBT), or multi-target stool DNA test or Colonoscopy or Flexible sigmoidoscopy (with or without periodic FIT) or CT colonography | ACS: Ages for screening: Begin at age 45 and continue until age 75; at ages 76-85, individualize recommendation (eg, based on general health, life expectancy, and patient preferences) ACS: Screening tests:
USPSTF: Ages for screening: 45 to 75; individualize for ages 76 to 85 USPSTF: Screening tests: Same as ACS, as well as flexible sigmoidoscopy every 10 years plus FIT every year ACP: Ages: Recommended for ages 50 to 75; not recommended for age > 75 or with life expectancy < 10 years ACP: Screening tests:
|
Lung cancer | Low-dose computed tomography (CT) | ACS: Yearly in people between ages 50 and 80 years who smoke or who quit smoking and have at least a 20-pack-year history of smoking |
* Patients at high-risk of certain cancers may need to be screened according to a different schedule. | ||
† Examinations for cancers of the thyroid, oral cavity, skin, lymph nodes, testes, and ovaries should also be done during routine medical care. | ||
Modified from the recommendations of the United States Preventative Services Task Force (USPSTF), the American Cancer Society (ACS), and the American College of Physicians (ACP) recommendations for breast cancer and colon cancer screening. | ||
