Developments in Screening Tests and Strategies for Colorectal Cancer

Abstract

Background. Worldwide, colorectal cancer (CRC) is the third most common cancer in men and second most common in women. It is the fourth most common cause of cancer mortality. In the United States, CRC is the third most common cause of cancer and second most common cause of cancer mortality. Incidence and mortality rates have steadily fallen, primarily due to widespread screening. Methods. We conducted keyword searches on PubMed in four categories of CRC screening: stool, endoscopic, radiologic, and serum, as well as news searches in Medscape and Google News. Results. Colonoscopy is the gold standard for CRC screening and the most common method in the United States. Technological improvements continue to be made, including the promising “third-eye retroscope.” Fecal occult blood remains widely used, particularly outside the United States. The first at-home screen, a fecal DNA screen, has also recently been approved. Radiological methods are effective but seldom used due to cost and other factors. Serum tests are largely experimental, although at least one is moving closer to market. Conclusions. Colonoscopy is likely to remain the most popular screening modality for the immediate future, although its shortcomings will continue to spur innovation in a variety of modalities.

K-ras Mutations as the Earliest Driving Force in a Subset of Colorectal Carcinomas

“…Unfortunately, it is sometimes difficult or even impossible to afford polyp tissue for molecular study, because of the inherent shortcomings of the process of colonoscopy (94). For instance, it may be hard to obtain tissue for molecular diagnosis from tiny polyps, because its restricted material is destined exclusively for histological diagnosis or because small polyps may not be visible in an inadequately prepared bowel.…”

“…narrow-band imaging) are used; advanced endoscopic technology is not available, however, in every Endoscopy Unit. The adenoma detection rate ranges from 7 to 44%, depending on the endoscopist's experience (94) and a recent study showed that 5%-32% of polyps are missed during colonoscopy, depending on their morphology (pedunculated or sessile), the preparation status of the bowel, the picture analysis of the colonoscope and the operator's characteristics (95). In these conditions, a precancerous lesion, possibly K-ras mutated, remain intact after a colonoscopy, where "all polyps were removed".…”

“…They should be first referred for high-definition white-light colonoscopy. In case endoscopic suspicions for a malignant or premalignant lesion are raised, advanced endoscopy techniques, as chromoendoscopy, narrow-bandimaging (NBI) -magnification endoscopy, cap-assisted colonoscopy or colonoscopy with the "third-eye retroscope" may be performed (94). They should de subjected to additional biopsies, targeted or not, to enable detection of other crucial mutations, e.g.…”

Cancer Screening 2016

“…Among these are stool-based tests, including the guaiac-based fecal occult blood test (FOBT), fecal immunochemical test (FIT), and stool deoxyribonucleic acid (DNA) test; endoscopic tests, including rigid and flexible sigmoidoscopy and colonoscopy; and imaging tests, including double contrast barium enema and computed tomography colonography (CTC). 27 While positive screens with stool-based and imaging-based tests must be followed with an endoscopic examination, endoscopic tests share the limitations of invasiveness, dietary preparation, and bowel cleansing, as well as the risk of perforation, over-sedation, and bleeding. 28 Colonoscopy, which allows for examination of the entire colon and removal of polyps with one procedure, is currently considered the gold standard for colorectal cancer screening.…”

“…28 Colonoscopy, which allows for examination of the entire colon and removal of polyps with one procedure, is currently considered the gold standard for colorectal cancer screening. 27 Additionally, colonoscopy is the required procedure to confirm positive findings from any other screening test. 28 Several retrospective case-control studies and one recent large prospective nonrandomized controlled trial have demonstrated dramatic reductions in colorectal cancer incidence with colonoscopy.…”