Screening Tests for Cancer

*Cancerscreening test facts medical author: Melissa Conrad Stöppler,MD

• Cancerscreening tests are tests that look for the presence ofcancerinhealthy人没有sympto或人ms of cancer.
• Cancer screening tests are designed to findcancersat an earlystagewhen they are more treatable.
• Some cancer screening tests have been found to lower thedeath rate(mortality rate) from certain cancers.
• Examples of some common cancer screening tests that are known to lower cancerdeathrates includecolonoscopyforcolon cancer,mammographyforbreast cancer, andPap smearforcervical cancer.
• Some cancer screening tests are recommended only for people at high risk of developing cancer, such asMRIof thebreast女性在风险增加ofbreast cancer.

Many cancer screening tests are in use. Some tests have been shown both to find cancer early and to lower the chance of dying from thedisease. Others have been shown to find cancer early but have not been shown to reduce the risk of dying from cancer; however, they may still be offered to people, especially those who are known to be at increased risk of cancer.

• Colonoscopy,sigmoidoscopy, and high-sensitivityfecal occult blood tests(FOBTs)
  These tests have all been shown to reduce deaths fromcolorectal cancer. Colonoscopy and sigmoidoscopy also help prevent狗万1.0 because they can detect abnormalcolon growths(polyps) that can be removed before they develop into cancer. Expert groups generally recommend that people who are at average risk for狗万1.0 cancer have screening at ages 50 through 75.
• Low-dose helical computed tomography
  This test to screen forlung cancerhas been shown to reducelung cancerdeaths among heavysmokersages 55 to 74.
• Mammography
  This method to screen forbreast cancerhas been shown to reduce mortality from the disease among women ages 40 to 74, especially those age 50 or older.
• Pap testandhuman papillomavirus(HPV) testing
  These tests reduce the incidence ofcervical cancerbecause they allow abnormal cells to be identified and treated before they become cancer. They also reduce deaths from cervical cancer. Testing is generally recommended to begin at age 21 and to end at age 65, as long as recent results have been normal.

• Alpha-fetoprotein blood test
  This test is sometimes used, along withultrasoundof theliver, to try to detectliver cancerearly in people at high risk of the disease.
• Breast MRI
  This imaging test is often used for women who carry a harmful mutation in theBRCA1gene or theBRCA2gene; such women have a high risk of breast cancer, as well as increased risk for other cancers.
• CA-125test
  This blood test, which is often done together with a transvaginal ultrasound, may be used to try to detectovarian cancerearly, especially in women with an increased risk of the disease. Although this test can help in diagnosingovarian cancerin 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 effectiveovarian cancerscreening test.
• Clinical breast exams and regularbreast self-exams
  Routine examination of the breasts by health care providers or by women themselves 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.
• PSA test
  This blood test, which is often done along with a digital rectal exam, is able to detectprostate cancerat an early stage. However, expert groups no longer recommend routine PSA testing for most men because studies have shown that it has little or no effect onprostate cancerdeaths and leads to overdiagnosis and overtreatment.
• Skin exams
  Doctors often recommend that people who are at risk forskin cancerexamine their skin regularly or have a health care provider do so. Such exams have not been shown to decrease the risk of dying fromskin 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.
• Transvaginal ultrasound
  This 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 mutation) or of子宫内膜癌(because they have a condition called Lynch syndrome). But it has not been shown to reduce deaths from either cancer.
• Virtual colonoscopy
  This test allows thecolonandrectumto be examined from outside the body. However, it has not been shown to reduce deaths fromcolorectalcancer.