Colorectal Cancer: Screening and Surveillance Recommendations

The value of extracolonic findings detected by CT colonography is mixed, with substantial costs associated with incidental findings, but occasional important extracolonic findings are detected, such as asymptomatic cancers and large abdominal aortic aneurysms. As a final point, the ACG is also concerned about the potential impact of CT colonography on adherence with follow-up colonoscopy and thus on polypectomy rates. Thus, if CT colonography substantially improves adherence, it should improve polypectomy rates and thereby reduce CRC, even if only large polyps are detected and referred for colonoscopy. On the other hand, if CT colonography largely displaces patients who would otherwise be willing to undergo colonoscopy, then polypectomy rates will fall substantially, which could significantly increase the CRC incidence [62]. Thus, for multiple reasons and pending additional study, CT colonography should be offered to patients who decline colonoscopy. It should be noted that CT colonography should only be offered for the purposes of CRC screening and should not be used for diagnostic workup of symptoms (eg, patient with active bleeding or inflammatory bowel disease).

• When should screening begin?

The American College of Gastroenterology continues to recommend that screening begin at age 50 years in average-risk persons (ie, those without a family history of colorectal neoplasia), except for African Americans, in whom it should begin at age 45 years [43]. The USPSTF does not currently provide specific recommendations based on race or ethnicity, but certain other subgroups of the average-risk population might warrant initiation of screening at an earlier or later age, depending on their risk. For example, the incident risk of CRC has been described to be greater in men than women [63]. In reviewing the literature, the writing committee also identified heavy cigarette smoking and obesity as linked to an increased risk of CRC and to the development of CRC at an earlier age.

For patients with a family history of CRC or adenomatous polyps, the 2008 MSTF guideline recommends initiation of screening at age 40 [11]. The American College of Gastroenterology recommendations for screening in patients with a family history are shown in Table 1. From a practical perspective, many clinicians have found that patients are often not aware of whether their first-degree relatives had advanced adenomas vs. small tubular adenomas, or whether their family members had non-neoplastic vs. neoplastic polyps. Given these difficulties, the American College of Gastroenterology now recommends that adenomas only be counted as equal to a family history of cancer when there is a clear history, or medical report containing evidence, or other evidence to indicate that family members had advanced adenomas (an adenoma ≥ 1 cm in size, or with high-grade dysplasia, or with villous elements) [43]. Continuation of the old recommendation to screen first-degree relatives of patients with only small tubular adenomas could result in most of the population being screened at age 40, with doubtful benefit.

• What are screening considerations in patients with genetic syndromes?

Patients with features of an inherited CRC syndrome should be advised to pursue genetic counseling with a licensed genetic counselor and, if appropriate, genetic testing. Individuals with FAP should undergo adenomatous polyposis coli (APC) mutation testing and, if negative, MYH mutation testing. Patients with FAP or at risk of FAP based upon family history should undergo annual colonoscopy until colectomy is deemed by both physician and patient as the best treatment [64]. Patients with a retained rectum after total colectomy and ileorectal anastomosis, ileal pouch, after total proctocolectomy and ileal pouch anal anastomosis, or stoma after total proctocolectomy and end ileostomy, should undergo endoscopic assessment approximately every 6 to 12 months after surgery, depending on the polyp burden seen. Individuals with oligopolyposis (< 100 colorectal polyps) should be sent for genetic counseling, consideration of APC and MYH mutation testing, and individualized colonoscopy surveillance depending on the size, number, and pathology of polyps seen. Upper endoscopic surveillance is recommended in individuals with FAP, but there are no established guidelines for endoscopic surveillance in MAP (MYH-associated polyposis) [43].