___________________________________________________________________________ Colorectal Cancer
To better understand potential provider and systemic obstacles to achieving higher utilization rates of colorectal cancer screen- ing, a national survey of colorectal cancer screening education, prioritization, and self-perceived preparedness was performed of 835 primary care residents. In regards to advising patients about colorectal cancer screening, current colorectal cancer screening guidelines, and criteria for familial colorectal cancer syndromes, a significant proportion of respondents felt they lacked sufficient knowledge in these areas. These data suggest opportunities to improve the colorectal cancer screening cur- riculum in primary care residency programs [129]. As colonoscopy has increasingly become widespread and preferred as a colorectal cancer screening approach, questions concerning its optimal use have emerged. Research has now established that the ability of colonoscopy to detect precancer- ous polyps and malignant tissue critically depends on examina- tion quality. Patient adherence to pre-colonoscopy preparation is also essential. Practice guidelines addressing these important issues have been published to bridge the knowledge gaps between the latest research, primary care, and specialist pro- viders. Practice guidelines for colorectal cancer screening are updated as new information becomes available. For example, in 2014 (and reiterated in 2024) the National Comprehensive Cancer Network (NCCN) expanded its recommendation for screening for Lynch syndrome to all patients diagnosed with colorectal cancer [130; 131]. COMMON COLORECTAL CANCER SCREENING TESTS There are several screening tests available for colorectal cancer, with varying levels of efficacy and clinical utility ( Table 4 ). Of these, the criterion standard is colonoscopy. Colonoscopy With screening colonoscopy, a colonoscope (a thin tube with a light and video camera on one end connected to a display monitor) is inserted through the rectum and guided through the length of the colon for observation on the monitor screen. Instruments to remove polyps and obtain biopsy are inserted through the rectum as needed [132]. Colonoscopy allows direct visualization of the colonic mucosa, lesion biopsy, and polyp removal over the entire colon. The sensitivity and specificity for colorectal cancer and advanced adenomas are very high, and colonoscopy is the confirmatory test used with all other screening approaches when positive findings occur [121]. Potential Complications and Harms Colonoscopy may fail to detect as many as 6% of colorectal malignancies, and the miss rate for adenomas smaller than 1 cm has ranged from 12% to 17% [133]. This is largely the result of high inter-operator variability in adenoma detection rate. Greater awareness of this hazard from inadequate colonoscopy performance has led to heightened emphasis on training and
continuous quality assurance of endoscopists [121]. In addi- tion, colonoscopy is an invasive procedure, requires an invasive bowel cleansing, is time-consuming and uncomfortable, and thus possesses several characteristics that negatively affect patient acceptance as a first-line screening test [121]. Clinically significant complications that require medical intervention are rare and include perforation, bleeding, and cardiovascular events. Complication rates may increase in older patients [134; 135]. More than 85% of serious colonos- copy complications occur during polypectomy, and a study of 97,000 colonoscopies found polypectomy associated with a seven-fold increase in risk of bleeding or perforation [136]. Up to 33% of patients report one or more minor, transient gastrointestinal symptoms after colonoscopy, and a review of 12 studies involving 57,742 colorectal cancer screening colo- noscopies in average-risk patients found the aggregate rate of serious complications was 2.8 per 1,000 procedures [135; 137]. Recommendations to Optimize the Adequacy of Colonoscopy Bowel Preparation The U.S. Multi-Society Task Force on Colorectal Cancer has published guidelines for adequate pre-colonoscopy bowel cleansing [138]. The goals of this consensus document are to provide expert, evidence-based recommendations for clinicians to optimize colonoscopy preparation quality and patient safety. The adequacy of pre-procedure bowel cleansing merits special attention because this patient factor is strongly associated with colonoscopy success. Up to 20% to 25% of colonoscopies are attempted in patients with inadequate bowel preparation, lead- ing to diminished adenoma detection rates, longer procedural time, lower cecal intubation rates, and increased electrocautery risk [139; 140; 141]. Patient risk factors for inadequate preparation include older age, male sex, higher BMI, history of inadequate preparation, history of constipation, and use of opioids or other constipat- ing medications. Patients with complex past medical histories or current conditions, including previous gastric or colonic resection, spinal cord injury, Parkinson disease, and stroke, are generally more difficult to prepare adequately. Diabetes is associated with the highest prevalence of inadequate bowel preparation [138]. A preliminary assessment of preparation quality should be done in the recto-sigmoid colon. If the indication is screening or surveillance and the preparation is clearly inadequate for polyp detection greater than 5 mm, terminate and resched- ule the procedure or attempt an additional bowel cleansing approach without canceling the procedure that day. If the colo- noscopy is complete to cecum, and the preparation ultimately is deemed inadequate, the examination should be repeated, generally within one year; intervals shorter than one year are indicated when advanced neoplasia is detected and there is inadequate preparation.
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