Page 63 Complete Your CE Test Online - Click Here into the rectum and sigmoid colon as air or carbon dioxide is pumped into the colon to expand it so the colon lining can be seen more clearly. During sigmoidoscopy, abnormal growths in the rectum and sigmoid colon can be removed for biopsy. The lower colon must be cleared of stool before sigmoidoscopy, but the preparation is less involved than that required for colonoscopy. People are usually not sedated for this test [200]. One randomized controlled clinical trial found that even just one sigmoidoscopy screening between 55 and 64 years of age can substantially reduce colorectal cancer incidence and mortality [44]. Sigmoidoscopy is limited in where it can detect cancer, since it can only look at the most distal portion (sigmoid), rather than the whole colon (the more proximal sections such as the ascending and transverse colon can harbor malignancy even though no abnormalities show up in the distal portion). This is a concern, since according to the National Cancer Institute, about three percent of patients with no distal adenomas have advanced proximal neoplasia. The NCI states that if colonoscopy is performed only in patients with distal polyps, about half the cases of advanced proximal neoplasia will not be detected [157]. The U.S. Preventive Services Task Force recommends sigmoidoscopy every five years along with FOBT every three years for people at average risk who have had negative test results [290]. Sigmoidoscopy cuts CRC mortality, as people over age 50 years who have regular sigmoidoscopy have a 60-70% lower risk of death from CRC versus those with no cancer screening [84,255]. The American Cancer Society notes that sigmoidoscopy every five years is slightly more effective when combined with an annual FOBT in people average risk [19]. They further note that patients with an abnormal sigmoidoscopy (polyps, cancer, or other problems) will need a colonoscopy. Standard (or optical) colonoscopy In this test, the rectum and entire colon are examined using a colonoscope, a flexible lighted tube with a lens for viewing and a tool for removing tissue. Like the shorter sigmoidoscope, the colonoscope is inserted through the anus into the rectum and the colon as air or carbon dioxide is pumped into the colon to expand it so the colonoscopist can see the colon lining more clearly. Evidence-based practice: Engaging the patient about colonoscopy prep beforehand in the patient’s native language, along with simple written instructions, improves the quality of bowel preparation and supports the sensitivity of colonoscopy, reducing false negatives and the need for repeat colonoscopy due to poor visibility [41]. During colonoscopy, abnormal growths in the colon and the rectum can be removed, including growths in the upper parts of the colon that are not reached by sigmoidoscopy. Polyps and other lesions removed during colonoscopy are typically treated as biopsies, and sent to pathology for examination. The kinds of lesions that can be detected include [165]: ● ● Nonneoplastic polyps (hyperplastic, juvenile, hamartomatous, inflammatory, and lymphoid polyps), which are not usually considered precursors of cancer. ● ● Neoplastic polyps (adenomatous polyps and adenomas) which are benign lesions that can undergo malignant transformation and become cancer. These are classified into three histologic types, with increasing malignant potential: tubular; tubulovillous; and villous, respectively. ● ● Cancers. A thorough cleansing of the entire colon is necessary before this test. Most patients receive some form of sedation during the test and will need a chaperone to get home safely. Indirect evidence suggests that colonoscopy reduces deaths from colorectal cancer by about 60-70% [246]. Additional studies are currently underway to more directly evaluate how effective colonoscopy is as a primary screening method in reducing death rates. Diagnostic use: The colonoscopy is not only used as a basic CRC screening test, but as a follow-up diagnostic test when any other type of CRC screening suggests an abnormality. Also, once a patient has CRC or an adenoma with high-grade dysplasia, their future screenings will no longer be the “average risk” person schedule and method. After such a diagnosis, the frequency of CRC screening typically increases, and the standard CRC test usually becomes colonoscopy rather than the less-invasive test options. Less obviously, if a polyp is found and removed during a screening colonoscopy, that colonoscopy may be billed and coded as a diagnostic procedure despite the original intent. This may mean the patient sees a change in their co-payment. There will also be pathology charges and other charges that are not seen with a screening procedure. CRC risk changes with family and personal history: The lifetime risk of CRC in the U.S. is about one in 20 (5%). But, a history of CRC in a first-degree relative more than doubles a person’s CRC risk. If a relative was diagnosed before age 45, or if more than one relative has had CRC, the risk is quadrupled. If the patient has previously had CRC or high risk adenomas, the CRC risk is also high. Finally, people with inflammatory bowel disease such as ulcerative colitis or Crohn’s Disease have more than double the usual risk of CRC [19]. In contrast, the more common condition of irritable bowel syndrome (IBS) does not increase the risk of CRC [21]. High-risk screening: Because higher CRC risk status varies by family history, genetics, and medical condition, there is no single “high risk” screening schedule for CRC. People with inherited genetic mutations like FAP should be screened starting at younger ages and more often than people at average CRC risk, but even people who have had adenomatous polyps may need closer follow- up. The American Cancer Society has guidelines on managing many different risk situations and how they should affect future screening or diagnostic colonoscopy: from hyperplastic polyps (same as average risk), to having colon cancer surgically removed (colonoscopy a year later; if normal, repeat in three years); to Lynch syndrome (colonoscopy every one to two years starting at age 20 to 25, or ten years before the youngest case in the immediate family). Patients at increased and high risk should be referred to an expert gastroenterologist to fully evaluate risk and perform colonoscopy as indicated. See Colorectal Cancer Prevention and Early Detection at colonandrectumcancerearlydetection/index or call 1-800-ACS-2345 for the details of high risk screening. Double-contrast barium enema This is a much older X-ray test that can detect large polyps and cancers by imaging the entire colon, although it is somewhat less sensitive than colonoscopy in finding smaller polyps or cancers. Barium sulfate flows into the colon through a tube placed in the anus to partly fill the colon, then air is introduced to expand the lumen of the colon and improve visibility. The double-contrast barium enema (DCBE) requires a full bowel preparation but does not usually involve sedation. However, polyps cannot be removed nor biopsies performed during the test. It also involves exposure to a low dose of radiation, and is not used much because of the ready availability of colonoscopy. Also, as time goes on, fewer radiologists know how to perform the procedure. A standard or optical colonoscopy is needed if abnormalities are found. False positive tests can occur. The American Cancer Society recommends it as an option for CRC screening every five years [14]. The U.S. Preventive Services Task Force does not recommend it as a screening method for colorectal cancer in part because it is less sensitive than colonoscopy.