Luminary Learning Gastrointestinal Disorder- Issue 1

Current Guidelines for Colonoscopy •  31 cancer-specific outcomes, risk-adjusted screening programs have been developed and are sup- ported by all major professional organizations (ACS, ACG, AGA, ASCRS, ASGE) with minor variations only [4–8]. The term screening in a strict sense is reserved to the testing of asympto- matic average-risk individuals. If there is an underlying high-risk constellation or clinical symptoms are present (such as positive fecal occult blood test, noticeable bleeding, anemia, change in bowel habits, etc.), not screening but surveillance or appropriate age-adjusted diagnostic workup should be initiated [6]. Below the age of 40 without additional risk factors, a flexible sigmoidoscopy (or even less) may be sufficient, but a full colon evaluation is recommended for clinical symptoms above the age of 40, or if there are additional findings or suspicion to suggest more proximal pathology. Screening efforts aim (a) at decreasing the burden of colorectal cancer by removing precan- cerous lesions, and (b) at reducing cancer mortality by detection of early rather than advanced disease [7, 9]. Effective screening is founded on the understanding that the multistep adenoma- carcinoma sequence may take up to 7–10 years from the first molecular change to a clinically manifest cancer; it should also take into consideration an individual’s genetic and disease or age- dependent risk profile for the development of colorectal cancer. Common screening tools fall into one of three categories: (a) complete or partial direct mucosal visualization (colonoscopy, flexible sigmoidoscopy), (b) indirect structural visualization by radiological imaging (surrogate tests), or (c) indirect nonstructural testing by stool analysis for fecal occult blood (guaiac-based FOBT versus immunochemical testing FIT) or fecal DNA (surrogate tests). For the procedural evaluations, most centers offer their patients to use con- scious sedation or monitored anesthesia care (MAC). It is important to state that in order to opti- mize visualization and increase accuracy of the evaluation, all direct and indirect structural tests alike require a complete and thorough bowel preparation, which is among the most significant obstacles for patients to agree to screening. All circumstances taken together, these tests impose a relevant burden as the patients likely will miss 1–2 days of work and require the utilization of a chaperone for transportation after the intervention. There is broad consensus among societies and organizations of medical professionals involved in developing screening guidelines that direct tests to detect cancer and adenomatous polyps should be preferred over the indirect tests where resources are available and if the individuals are amenable [7]. In populations where the required infrastructure is lacking, as well as in patients who are either unwilling and/or unable to undergo one of the structural tests or the necessary dietary and bowel cleansing preparation before, the use of stool-based colorectal cancer screening tests are an acceptable alternative. In the United States, colonoscopy is recognized as the most effective screening tool and has become common practice with an estimated more than ten million procedures performed annu- ally [9]. The advantages of the procedure are obvious as it allows for direct mucosal inspection of the entire colon and also provides opportunity for biopsy sampling for further evaluation as well as for definitive therapeutic interventions by polypectomy in the case of precancerous lesions or early stage cancers [9]. Data from the National Polyp Study, as well as other reports, have demon- strated that colonoscopy with polypectomy is able to reduce the incidence of polyps by 76–90% and the CRC mortality by 53% [10, 11].