Cancer Screening Tests
Cancer screening tests aim to find cancer before it causes symptoms and when it may be easier to treat successfully. An effective screening test is one that
Finds cancer early
Reduces the chance that someone who is screened regularly will die from the cancer
Has more potential benefits than harms (possible harms of screening tests include bleeding or other physical damage, false-positiveor false-negative test results, and overdiagnosis—the diagnosis of cancers that would not have caused problems and did not need treatment)
Recommended cancer screening tests
Several cancer screening tests are considered effective and recommended by expert groups.
Breast cancer screening
Screening mammography has been shown to reduce deaths from breast cancer among women ages 40 to 74, especially those ages 50 to 69.
Expert groups generally recommend that screening start at age 50 for women at average risk.
Cervical cancer screening
Human papillomavirus (HPV) tests and Pap tests are recommended cervical cancer screening tests that can be used alone or in combination. These tests prevent the disease because they allow abnormal cells to be found and treated before they become cancer.
Expert groups generally recommend that testing begin at age 21 and end at age 65 (for women who have had adequate prior screening and are not otherwise at high risk for cervical cancer).
Colorectal cancer screening
Several screening tests, including colonoscopy, sigmoidoscopy, and stool tests (high-sensitivity fecal occult blood tests and stool DNA tests) have been shown to reduce the risk of dying from colorectal cancer. In addition to detecting colorectal cancer early, colonoscopy and sigmoidoscopy can help prevent the disease from developing. That’s because these tests can find abnormal colon growths (polyps) that can be removed before they become cancer.
Expert groups generally recommend that people who are at average risk for colorectal cancer have screening with one of these tests at ages 45 or 50 through 75.
Lung cancer screening
Low-dose helical computed tomography, a type of CT scan, has been shown to reduce lung cancer deaths among heavy smokers.
Expert groups generally recommend screening of some current or former heavy smokers at ages 50 to 80.
Alpha-fetoprotein blood test
The alpha-fetoprotein blood test is sometimes used, along with ultrasound of the liver, to try to detect liver cancer early in people at high risk of the disease.
The CA-125 blood test, which is often done together with a transvaginal ultrasound, may be used to try to detect ovarian cancer early, especially in women with an increased risk of the disease. Although this test can help to diagnose ovarian cancer in women who have symptoms and can be used to evaluate the recurrence of cancer in women previously diagnosed with the disease, it has not been shown to be an effective ovarian cancer screening test.
Clinical breast exams and regular breast self-exams
Routine examination of the breasts by health care providers (clinical breast exam) or by women themselves (breast self-exam) has not been shown to reduce deaths from breast cancer. However, if a woman or her health care provider notices a lump or other unusual change in the breast, it is important to get it checked out.
Multicancer early detection tests
Multicancer early detection (MCED) tests are tests that measure biological signals in body fluids that may be shed by cancer cells. These signals are also known as biomarkers or tumor markers. Depending on which signals the MCED test measures, it may detect several different types of cancer. Whether MCED tests are effective for cancer screening in people without symptoms is unknown and needs to be assessed through randomized clinical trials.
The prostate-specific antigen (PSA) blood test has been used, often along with a digital rectal exam, for prostate cancer screening. However, expert groups no longer recommend routine PSA testing for most men because many prostate cancers detected with PSA testing are not deadly, and early detection and treatment of PSA-detected cancers has not been shown to reduce the chance of dying from prostate cancer.
Doctors often recommend that people who are at risk for skin cancer examine their skin regularly or have a health care provider do so. Such exams have not been shown to decrease the risk of dying from skin cancer, and they may lead to overtreatment. However, people should be aware of changes in their skin, such as a new mole or a change to an existing mole, and report these to their doctor promptly.
The transvaginal ultrasound imaging test, which can create pictures of a woman’s ovaries and uterus, is sometimes used in women who are at increased risk of ovarian cancer (because they carry a harmful BRCA1 or BRCA2 gene mutation) or of endometrial cancer (because they have a condition called Lynch syndrome). But it has not been shown to reduce deaths from either cancer.
A virtual colonoscopy allows the colon and rectum to be examined from outside the body. Although it has not been shown to reduce deaths from colorectal cancer and may reveal possible problems outside the colon that then need to be investigated further, this test may be recommended if it is the only colorectal cancer screening test a person finds acceptable.
Other screening tests
Screening tests that have not been shown to be effective may still be offered, especially to people who are known to be at increased risk of certain cancers.