Colorectal Cancer ____________________________________________________________________________
Surveillance colonoscopy in patients with inflammatory bowel syndrome should include extensive biopsies of all anatomic segments of colorectal mucosa. Definitive data are lacking to inform the optimal surveillance intervals, but one- to three- year intervals are suggested. Careful mucosa inspection and sufficient number of biopsy specimens should be obtained from all anatomic segments of the colon. Newer Imaging Techniques Chromoendoscopy is more sensitive in dysplasia detection than white-light endoscopy when used by endoscopists with expertise. However, the natural history of chromoendoscopi- cally detected dysplasia is unknown. In addition, more research is needed to determine the utility of narrow band imaging and confocal endomicroscopy in detecting dysplasia. Chemopreventive Agents Ursodeoxycholic acid has demonstrated significant reductions in colorectal cancer in patients with ulcerative colitis who also have primary sclerosing cholangitis. Aminosalicylates are also considered chemopreventive against colorectal cancer. Oral or topical corticosteroids, while demonstrating antineoplastic effects in clinical trials, are associated with too many side effects for routine chemopreventive use. There is insufficient evidence to inform a recommendation for or against the use of azathio- prine, 6-mercaptopurine, folic acid, calcium or multivitamin supplements, or statins. COLORECTAL CANCER SCREENING As noted, the United States is the only developed country experiencing declining incidence rates of colorectal cancer, despite the increase in colorectal cancer risk factors such as obesity [4]. Increasingly widespread colorectal cancer screening is believed to be the root of this seeming paradox. Colorectal cancer is a serious disease but in many cases is preventable, and its incidence, mortality, and financial bur- den to society make it an important healthcare concern. The usually long and often asymptomatic premalignant natural history and the clinical features of colorectal cancer make the malignancy amenable to prevention by screening. Colonoscopy has become the dominant screening approach, and optical (versus computed tomography [CT] or “virtual”) colonoscopy has the advantage of providing cure via polypectomy during the session [120]. Evidence supports screening for colorectal cancer as part of routine care for all adults 45 to 50 years of age or older, espe- cially those with first-degree relatives with colorectal cancer, for the following reasons [121; 122]: • Increased incidence in those 50 years and older
• Better survival of patients with early-stage lesions • Relative simplicity and accuracy of screening tests Consistent evidence supports population-level colorectal can- cer screening, which has become the foundation for primary colorectal cancer prevention. In a 2012 study involving 2,602 patients initially referred to colonoscopy for adenomas and nonadenomatous polyps from 1980 to 1990, participants were followed up to 23 years (median: 15.8 years). Their mortality from colorectal cancer was compared against the expected colorectal cancer mortality in the general popula- tion. Colonoscopy was associated with a 53% reduction in mortality (12 colorectal cancer deaths versus 25.4 expected). During the first 10 years post-polypectomy, colorectal cancer mortality was comparable between patients with adenomas or nonadenomatous polyps [123]. In another study, 46,551 healthy subjects between 50 and 80 years of age were randomized to annual or biennial fecal occult blood testing (FOBT) or no screening from 1976 to 1992. Those with positive FOBT screens received colonoscopy and treatment for malignant findings. At 30-year follow-up, 33,020 had died, 732 from colorectal cancer, including 200/11,072 (1.8%) with annual, 237/11,004 (2.2%) with biennial, and 295/10,944 (2.7%) with no screening. At 30 years, colorectal cancer mortality was reduced by 32% with annual screening and 22% with biennial screening compared with no colorectal cancer screening [124]. Researchers compared 3,148 patients with first diagnosis of colorectal cancer with 3,274 non-colorectal cancer subjects to assess associations between colonoscopy for specific indications and the risk of colorectal cancer over a 10-year period. History of screening colonoscopy was associated with a reduction of colorectal cancer risk of 89% and of malignancy in the right colon of 78%. History of diagnostic colonoscopy (and indica- tion) was associated with colorectal cancer risk reduction of 67% with assessment of positive FOBT; 67% with surveillance after a preceding colonoscopy; 72% with assessment of rectal bleeding; and 85% with assessment of abdominal symptoms [125]. Another large study followed 40,826 patients for a median 7.7 years to study the impact of adenoma removal during screening colonoscopy on colorectal cancer mortality. Using data from the Norway national cancer and cause-of-death reg- istries, researchers found that, relative to expected colorectal cancer mortality (the general Norwegian population), adenoma removal during screening was associated with a 25% reduction in mortality rate [126]. Unfortunately, despite sophisticated nationwide efforts to elevate screening awareness, routine screening of eligible individuals remains low [127]. Currently, about one in three Americans 50 years of age or older, for whom screening is recommended, have never been screened consistent with cur- rent guidelines [128].
• Ability to identify high-risk groups • Slow growth of primary lesions
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