Letters To The Editor

Colorectal cancer screening: Colonoscopy has disadvantages

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To the Editor: In the article, “ Colorectal cancer screening: Choosing the right test ,” the authors offer an excellent review, but restrict the discussion to just 2 of the many options. Screening compliance improves when clinicians and patients can select their preferred screening approach, and other noninvasive or minimally invasive approaches also deserve consideration and may well be superior. It is important that both the patient and the healthcare provider be fully aware of the advantages and disadvantages of each method.

The article is overly generous in its description of the accuracy and sensitivity of optical colonoscopy. The statement that colonoscopy visualizes the entire colon in more than 98% of cases is not supported by the biomedical literature or clinical experience. The measure of colonoscopy accuracy is best quantified by a review of more than 15,000 tandem colonoscopies that showed an average polyp miss rate of 22% using standard colonoscopes, and a 69% polyp miss rate compared with full-spectrum colonoscopes with greater fields of view. 1–3 Between 5% and 10% of colonoscopies are technically incomplete and do not reach the cecum. Only 35% of colonoscopy bowel preps are excellent, and 21% are so poor that the procedure cannot be completed. 4–8 Colorectal cancers are frequently missed at colonoscopy, with a rate of 7% quoted in the literature for interval cancer development. 9–16 Studies of computed tomography colonography (virtual colonoscopy) have confirmed that between 10% and 20% of the colonic mucosa is hidden from view on optical colonoscopy by tall haustral mucosal folds. 17,18 The operator variation measured by adenoma detection rates can exceed a 10-fold differential.

Colonoscopy is an important and valuable diagnostic and therapeutic tool. The disadvantages include significant cancer and polyp miss rates, high discomfort, high expense, potentially life-threatening complications, time- and resource-intensive utilization, high loss of patient work productivity, challenging and frequently inadequate preparation, higher risk of metachronous cancer and polyp spread, and high operator variability of quality. 19–24 Unfortunately, while colonoscopy is an important tool, it does not come anywhere close to a score of 98% and should not be considered the gold standard for colorectal cancer screening. 25

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