Colon cancer screening
Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening; Fecal immunochemical test; Stool DNA test; sDNA test; Colorectal cancer - screening; Rectal cancer - screening
Colon cancer screening can detect polyps and early cancers in the large intestine. This type of screening can find problems that can be treated before cancer develops or spreads. Regular screenings may reduce the risk for death and complications caused by colorectal cancer.
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
One of the important jobs of the large intestine is to absorb the remaining water from the food residue passing through the intestines. The residue that is left remains in a semisolid state and is propelled toward the rectum by peristalsis. Through reflexes which are triggered by a full colon, feces is eliminated from the body.
A barium enema in a patient with cancer of the large bowel (sigmoid area).
A fecal occult blood test is a noninvasive test that detects the presence of hidden blood in the stool. Blood in the stool that is not visible is often the first, and in many cases the only, warning sign that a person has colorectal disease, including colon cancer.
Capsule endoscopy is a test procedure in which a camera inside a small capsule takes pictures of the lining of your digestive system. The capsule is about the size of a large vitamin pill. After swallowing it, the capsule travels the length of your digestive system and transmits images to a wearable recorder.
Colon cancer may not be talked about as often as other cancers, like breast cancer, prostate or lung cancer, but it's actually one of the leading causes of cancer deaths. It is for this reason it's very important to stay on top of your colon health. The colon is your large intestine, the long, upside-down U-shaped tube that is toward the end of the line for getting rid of waste in your body. Colon cancer can start in the lining of the intestine, or at the end of it, called the rectum. Let's try to better understand Colon cancer. You're more likely to get the disease if you're over age 60, especially if you have a family history of colon cancer, inflammatory bowel disease, diabetes, or obesity. Smoking cigarettes and drinking alcohol has also been found to increase your risk of getting colon cancer. Although the data are not consistent, eating red meat or processed meats may increase the risks of colon cancer as well. Lean, unprocessed red meat, may be associated with less risk. If you have symptoms, they may include pain in your abdomen, blood in your stool, weight loss, or diarrhea. But hopefully, you'll get diagnosed before you have any symptoms, during a regular screening test like a colonoscopy or sigmoidoscopy. These tests use special instruments to see inside your colon and rectum to look for any cancerous or pre-cancerous growths, called polyps. If your doctor discovers that you do have colon cancer, unfortunately, you'll need to have a few more tests, including scans of your abdomen to find out whether the cancer has spread, and if so, where in your body it's located. So, how is colon cancer treated? That really depends on how aggressive your cancer is and how far it's spread, but usually colon cancer is removed with surgery, or killed with chemotherapy or radiation. You may get one, or a combination, of these treatments. Colon cancer is one of the more treatable cancers. You can be cured, especially if you catch it early. Spotting colon cancer when it's still treatable is up to you. If you're over age 50, you need to get screened with a colonoscopy. During this test, your doctor can find, and remove colon polyps before they have a chance to turn cancerous. And, regular physical activity and eating at least some fruits and vegetables daily, perhaps with unprocessed wheat bran, can help prevent it. If you want to prevent colon cancer, you'll also want to avoid processed and charred red meats, and smoking, and excess calories, and alcohol.
Information
SCREENING TESTS
There are several ways to screen for colon cancer.
Stool test:
- Polyps in the colon and small cancers can cause small amounts of bleeding that cannot be seen with the naked eye. But blood can often be found in the stool.
- This method checks your stool for blood.
- A common test used is the fecal immunochemical test (FIT). The fecal occult blood test (gFOBT) was commonly used in the past. Another stool test, commonly known as Cologuard checks for both blood and abnormal stool DNA (sDNA).
Sigmoidoscopy:
- This test uses a small flexible scope to view the lower part of your colon. Because the test only looks at the last one third of the large intestine (colon), it may miss some cancers or polyps that are higher in the large intestine.
- Sigmoidoscopy and a stool test may be used together.
Colonoscopy:
- A colonoscopy is similar to a sigmoidoscopy, but the entire colon can be viewed.
- Your health care provider will give you the steps for cleansing your bowel. This is called bowel preparation.
- During a colonoscopy, you receive medicine to make you relaxed and sleepy.
- Sometimes, CT scans are used as an alternative to a regular colonoscopy. This is called a virtual colonoscopy (or CT colography).
Other test:
- Capsule endoscopy involves swallowing a small, pill-sized camera that takes a video of the inside of your large intestine. The method is being studied, but it is not recommended for standard screening at this time.
SCREENING FOR AVERAGE-RISK PEOPLE
There is not enough evidence to say that any one screening method is best. Colonoscopy is the most thorough but also has the highest risk. Talk to your provider about which test is right for you.
All adults should have a colon cancer screening test starting at age 45.
The most commonly recommended screening options for people with an average risk for colon cancer:
- Colonoscopy every 10 years starting at age 45
- FIT every year (colonoscopy is needed if results are positive)
- Flexible sigmoidoscopy every 5 years or every 10 years plus stool testing with FIT done every year
Other screening options include the following. If any of these tests are positive, colonoscopy is recommended:
- sDNA-FIT every 3 years
- CT colonography (virtual colonoscopy) every 5 years
SCREENING FOR HIGHER-RISK PEOPLE
People with certain risk factors for colon cancer may need earlier (before age 45) or more frequent testing.
More common risk factors are:
- A family history of inherited colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC).
- A strong family history of colorectal cancer or advanced adenomatous polyps. This usually means close relatives (parent, sibling, or child) who developed these conditions younger than age 60.
- A personal history of colorectal cancer or polyps.
- A personal history of long-term (chronic) inflammatory bowel disease (for example, ulcerative colitis or Crohn disease).
Screening for these groups is more likely to be done using colonoscopy.
References
Garber JJ, Chung DC. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 126.
National Cancer Institute website. Colorectal cancer screening (PDQ) -- health professional version.
Patel SG, May FP, Anderson JC, et al. Updates on age to start and stop colorectal cancer screening: Recommendations from the U.S. Multi-Society Task Force on colorectal cancer. Gastroenterology. 2022;162(1):285-299. PMID: 34794816
Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030. PMID: 28555630
Shaukat A, Kahi CJ, Burke CA, Rabeneck L, Sauer BG, Rex DK. ACG Clinical Guidelines: Colorectal cancer screening 2021. Am J Gastroenterol. 2021;116(3):458-479. PMID: 33657038
US Preventive Services Task Force; Davidson KW, Barry MJ, et al. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2021;325(19):1965-1977. PMID: 34003218
Wolf AMD, Fontham ETH, Church TR, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA Cancer J Clin. 2018;68(4):250-281. PMID: 29846947
Version Info
Last reviewed on: 8/12/2024
Reviewed by: Jenifer K. Lehrer, MD, Gastroenterologist, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
