Colorectal cancer screening: Difference between revisions
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====Fecal Occult Blood Testing==== | ====Fecal Occult Blood Testing==== | ||
*A [[fecal occult blood]] test (FOBT) is a test for blood in the stool | *A [[fecal occult blood]] test (FOBT) is a test for blood in the stool | ||
* There are two types of tests that can be used for detecting occult blood in stools | * There are two types of tests that can be used for detecting occult blood in stools: guaiac-based (chemical test) and immunochemical | ||
====Endoscopy==== | ====Endoscopy==== | ||
Revision as of 13:56, 14 July 2015
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Colorectal cancer Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Colorectal cancer screening On the Web |
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American Roentgen Ray Society Images of Colorectal cancer screening |
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Risk calculators and risk factors for Colorectal cancer screening |
To view the screening of familial adenomatous polyposis (FAP), click here
To view the screening of hereditary nonpolyposis colorectal cancer (HNPCC), click here
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Elliot B. Tapper, M.D., Saarah T. Alkhairy, M.D.
Overview
Current guidelines suggest that a colonoscopy is the best screening tool for colon cancer; in fact, colonoscopy detects colon cancer in 98-99% of the cases.[1] The most common indicator of high risk is a first-degree relative with colorectal cancer. A colonoscopy every 10 years reduces the risk of left-sided colon cancer, but not as much for right sided colon cancer. Right sided colon cancers are more likely to be missed because they are harder to reach and they could be flat, which means they would be harder to detect. Flat growths (non-polypoid) are difficult to detect and are more likely to progress to colon cancer compared to cylindrical polyps.[1] Spray on dyes may better help to detect flat growths.
Colorectal Cancer Screening
Colorectal cancer can take many years to develop and early detection of colorectal cancer greatly improves the chances of a cure.
Identification of High-risk Individuals
The most common indicator of high risk is a first-degree relative with colorectal cancer[2].
- If the first-degree relative was diagnosed with CRC before 50 years of age
- The individual should be suspected of a hereditary syndrome and referred to a specialist
- The specialist will obtain a complete family history, consider genetic counseling and testing, and determine appropriate timing for endoscopic surveillance
- If a first-degree relative was diagnosed with CRC at 50 years of age or older
- The lifetime risk of CRC nearly doubles among his or her family members
- Colonoscopy is the preferred screening test for these individuals
- Screening should be initiated either when they are 40 years old or when they are 10 years younger than the age at which the family member received the diagnosis, whichever comes first
- If the individual is diagnosed with chronic ulcerative colitis or colitis due to Crohn's disease
- There is an increased risk for CRC and the individual should undergo surveillance with colonoscopy, generally beginning 8 to 10 years after the diagnosis
Clinical practice guidelines
Clinical practice guidelines by the United States Preventive Service Task Force (USPSTF) in 2008 stated:[3]
- "The USPSTF recommends screening for colorectal cancer using fecal occult blood testing, sigmoidoscopy, or colonoscopy in adults, beginning at age 50 years and continuing until age 75 years"
- "The USPSTF recommends against routine screening for colorectal cancer in adults 76 to 85 years of age. There may be considerations that support colorectal cancer screening in an individual patient"
- "The USPSTF recommends against screening for colorectal cancer in adults older than age 85 years"
The USPSTF concludes that the evidence is insufficient to assess the benefits and harms of computed tomographic colonography and fecal DNA testing as screening modalities for colorectal cancer.
The American College of Gastroenterology recommends:[4]
- Screening in African Americans should begin at age 45 years
- CT colonography every 5 years is the radiographic screening alternative, when patients decline colonoscopy
- Fecal immunochemical test for blood (FIT) is preferred over guaiac-based fecal occult blood testing
Types of Screening Methods
Fecal Occult Blood Testing
- A fecal occult blood test (FOBT) is a test for blood in the stool
- There are two types of tests that can be used for detecting occult blood in stools: guaiac-based (chemical test) and immunochemical
Endoscopy
- A sigmoidoscopy is a lighted probe (sigmoidoscope) that is inserted into the rectum and lower colon to check for polyps and other abnormalities
- A colonoscopy is a lighted probe (colonoscope) that is inserted into the rectum and the entire colon to look for polyps and other abnormalities that may be caused by cancer. A colonoscopy has the advantage that if polyps are found during the procedure they can be immediately removed, and the tissue can also be taken for biopsy. The American Society for Gastrointestinal Endoscopy has released quality indicators for screening colonoscopy, which include:[5]
- Documentation of prep quality
- Photo documentation of cecal intubation
- Withdrawal time of 6 minutes or more
- Adenoma detection rate of greater than 25% in males and 15% in females greater than 50 years old.
Genetic Testing
- Genetic counseling and genetic testing is a screening modality for families who may have a hereditary form of colon cancer, such as hereditary nonpolyposis colorectal cancer (HNPCC) or familial adenomatous polyposis (FAP)
Other Screening Techniques
- Double contrast barium enema (DCBE)
- First, an overnight preparation is taken to cleanse the colon. An enema containing barium sulfate is administered, then air is insufflated into the colon, distending it. The result is a thin layer of barium over the inner lining of the colon which is visible on X-ray films. A cancer or a precancerous polyp can be detected this way. This technique can miss the (less common) flat polyp.
- This replaces X-ray films in the double contrast barium enema (above) with a special computed tomography scan and requires special workstation software in order for the radiologist to interpret. This technique is approaching colonoscopy in sensitivity for polyps. However, any polyps found must still be removed by standard colonoscopy.
- The measurement of the patient's blood for elevated levels of certain proteins can give an indication of tumor load. In particular, high levels of carcinoembryonic antigen (CEA) in the blood can indicate metastasis of adenocarcinoma. These tests are frequently false positive or false negative, and are not recommended for screening, it can be useful to assess disease recurrence.
- Stool DNA testing
- This detects DNA shed into the stool from the cells of pre-malignant adenomas and cancers. The DNA is not degraded during the digestive process and remain stable in the stool.
References
- ↑ 1.0 1.1 American Society of Clinical Oncology. 2010. Progress in Cancer Screening. http://owl.english.purdue.edu/owl/resource/560/10/
- ↑ Lieberman, David A. (2009). "Screening for Colorectal Cancer". New England Journal of Medicine. 361 (12): 1179–1187. doi:10.1056/NEJMcp0902176. ISSN 0028-4793.
- ↑ U.S. Preventive Services Task Force (2008). "Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement". Ann Intern Med. 149 (9): 627–37. PMID 18838716.
- ↑ Rex DK, Johnson DA, Anderson JC, et al. American College of Gastroenterology guidelines for colorectal cancer screening 2009.Am J Gastroenterol. 2009 Mar;104(3):739-50.
- ↑ Rex DK, Petrini JL, Baron TH, Chak A, Cohen J, Deal SE; et al. (2006). "Quality indicators for colonoscopy". Am J Gastroenterol. 101 (4): 873–85. doi:10.1111/j.1572-0241.2006.00673.x. PMID 16635231.