Scoping Out Colon Cancer's Varied Terrain

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Science  28 Mar 2008:
Vol. 319, Issue 5871, pp. 1735
DOI: 10.1126/science.319.5871.1735a

Colorectal cancer remains a leading cause of cancer deaths in the developed world despite the availability of a well-established screening procedure—colonoscopy—that can detect the disease at an early stage. Although patient noncompliance with screening recommendations is a major contributing factor to the disease's continued prevalence, questions have also been raised about whether conventional colonoscopy can reliably detect the full range of premalignant lesions that eventually progress to cancer. These lesions include not only adenomatous polyps but also morphologically subtle “flat” lesions. Soetikno et al. recently reported that flat lesions were present in nearly 10% of 1800 patients screened at a veterans' hospital and that these lesions were five times as likely as polyps to show malignant features.

These findings underscore the importance of ongoing efforts to improve the sensitivity of colonoscopy (the inner surface of a healthy colon is shown above). A progress report on one such strategy is provided by Hsiung et al., who used bacteriophage phage display libraries to identify a small peptide that binds preferentially to human premalignant colonic tissue. When a fluorescein-conjugated version of the peptide was sprayed onto the colon's inner surface and imaged by confocal microendoscopy during routine colonoscopy, it was found to bind to premalignant versus normal cells with 81% sensitivity and 82% selectivity. Although not directly tested in this study, such targeted peptides could in principle be optimized to detect the subtler lesions that are missed by current technologies. — PAK

J. Am. Med. Assoc. 299, 1027 (2008); Nat. Med. 14, 10.1038/nm1692 (2008).

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