Reducing polyp miss rate during colonoscopy using optical spectroscopy

Colorectal cancer is the second leading cause of cancer deaths in the U.S.. While colonoscopy is the "gold standard" of colon cancer screening, it does miss neoplastic lesions. The miss rate for adenomatous polyps is estimated to be >25%. Thus, improving sensitivity of colonoscopy for polyp detection would have major clinical importance. Most polyps are missed because they are out of the field of view of a colonoscopist or obscured due to poor bowel preparation. Particularly difficult to visualize are "flat and depressed" lesions which, unfortunately, are also more aggressive.

Our group was the first to observe a novel biological phenomenon of early increase in mucosal blood supply (EIBS): early colon carcinogenesis is accompanied by EIBS that is present not only in a precancerous lesion itself (e.g. adenomatous polyp) but also in the endoscopically normal-appearing mucosa surrounding the lesion. The effect is the most pronounced within 30 cm (~1/3 of colon) from adenomas. Although blood supply increase to tumors has been well documented, we were the first to observe blood supply augmentation in the field of a precancerous lesion in histologically normal-appearing mucosa.

EIBS can be used to improve polyp detection: assessment of microvascular blood content in the endoscopically normal mucosa may enable rapid and accurate discrimination between colonic segments that harbor neoplasia from those that are neoplasia-free. The major thrusts of our work are 1) development of new endoscopically compatible fiber-optic probes for EIBS detection in vivo, 2) elucidating molecular mechanisms of EIBS, and 3) large-scale, multi-site clinical trials. The methodology has been supported by clinical data in more than 400 patients.

Our research spans from the development of new optical technologies and clinical instrumentation to large-scale, multi-site clinical trials and the methodology has been supported by clinical data in more than 1,000 patients.

This may lead to dramatic advances in both medicine and cancer research as it may no longer be necessary to localize or interrogate precancerous tissue. Our vision is that this new methodology may enable screening for major types of cancer during an annual physical exam by a primary care physician. Colon neoplasia can be detected without colonoscopy via the examination of cells in the rectum, lung cancer by the analysis of cells brushed from the buccal mucosa, and pancreatic cancer by the analysis of duodenal cells, just to name a few potential applications.

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Backman's Biophotonics Laboratory at Northwestern University

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