___________________________________________________________________________ Colorectal Cancer
Surveillance Colonoscopy Surveillance colonoscopy is at least moderately effective in reducing colorectal cancer risk in patients with inflammatory bowel syndrome. It is recommended for patients with inflammatory bowel disease who are at an increased risk of colorectal cancer. Patients most likely to benefit are those with extensive ulcerative colitis or Crohn disease. 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 chromoendoscopically 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 azathioprine, 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 burden 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 [119].
The extent of macroscopic and histologic inflammation is associated with increased risk of colorectal cancer, which can develop in areas of endoscopically normal but histologically active colitis. Colorectal cancer can occur in areas where colitis has remitted or where histologic findings show inactive colitis such as crypt distortion in the absence of active inflammation. Lack of endoscopic inflammation at the time of neoplastic detection does not mean absence of inflammation in the area before neoplastic development, and risk of neoplasia is not increased in mucosa that has never been inflamed. Thus, histologic instead of macroscopic evidence of tissue changes from inflammatory bowel syndrome serves as a more accurate determinant for assessing colorectal cancer risk. In the context of surveillance, extent of disease should be defined histologically [118]. Practice recommendations for the diagnosis and treatment of colorectal cancer in inflammatory bowel syndrome patients were developed and published by the American Gastroenterology Association [118]. The guideline format presents a series of clinically relevant questions raised by an expert panel, followed by the response based on analysis of the published research. Natural History of Dysplasia Colorectal cancer in inflammatory bowel syndrome develops from dysplasia in most cases, and although imperfect, dysplasia is considered the best marker of colorectal cancer risk in inflammatory bowel syndrome. Predicting the natural history of dysplasia is more difficult, because dysplasia is present in 75% to 90% of patients with inflammatory bowel syndrome and colorectal cancer, but colorectal cancer can develop in the absence of previous history of dysplasia. Not all patients with low-grade dysplasia progress through a phase of detectable high-grade dysplasia before developing cancer. Importantly, interpretation of dysplasia in mucosal biopsy specimens is highly subject to observer subjectivity. Therefore, pathologists with particular expertise in gastrointestinal disorders should review all cases diagnosed as indefinite, low-grade dysplasia, or high-grade dysplasia. Colectomy Strong evidence indicates that patients with inflammatory bowel syndrome and a non-adenoma-like dysplasia-associated lesion or mass should receive a colectomy. Patients with inflammatory bowel syndrome and an adenoma-like dysplasia- associated lesion or mass, without evidence of flat dysplasia elsewhere in the colon, can be managed safely by polypectomy and continued surveillance. There is also strong evidence that colectomy for flat high-grade dysplasia treats undiagnosed synchronous cancer and prevents metachronous cancer. However, current evidence is insufficient to assess the balance of benefits and harms.
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