Endoscopy, morphology, morphometry and molecular markers: predicting cancer risk in colorectal adenoma

Abstract

The evaluation of short- and long-term risk for developing cancer in patients with colorectal adenomas is controversial. Good, reliable predictors of cancer risk in any adenoma are currently lacking and are limited to adenoma size, number and histologic type. In fact, the evaluation of any adenoma or precancer lesion (e.g., hyperplastic polyps, serrated adenoma or aberrant crypt foci) within the colorectum may be assessed by a number of techniques ranging from direct visualization through the endoscope, to microscopic assessment, and to evaluation at the molecular level. Emerging techniques may yield improved methods of adenoma risk-assessment in the near future. For one, newer endoscopy technologies include chromoendoscopy or endocytoscopy, which now render endoscopists able to resolve the surface and subsurface mucosa at cellular resolution in vivo and in real time - thus, bringing the microscope to the patient's bedside. This new era in endoscopic imaging is dubbed 'histoendoscopy'. Further, while traditional views of classifying protruding and sessile lesions include those of Haggitt, the sm-classification, the Japanese and the so-called Vienna classifications to evaluate neoplasia, the development of new molecular techniques may give way to new methods of classifying preneoplasia and precancerous lesions. This review discusses some pros and cons of risk evaluation technologies in the colorectal tract by endoscopy, microscopy, and quantitative and molecular features. The morphometry-based studies performed over the past decades for the quantitative assessment of cellular and nuclear features within adenomas have failed to yield results amenable for clinical translation and are unlikely to improve further and gain widespread use with current technology. Rather, emerging knowledge of pathway-specific markers through the outlining of a molecular classification will likely be the basis for improved detection and diagnosis. The emerging genomic and proteomic technologies allowing for noninvasive tests to detect (asymptomatic) cancer and neoplasia are discussed. Lastly, the importance of recognizing bias and pitfalls and the adherence to guidelines for biomarker research are addressed.

Long-term clinical outcome of the surgically resected intraductal papillary neoplasm of the bile duct

“…Concerning this issue, the histopathological description of the progression of papillary or villous colorectal neoplasms is well established. Early colorectal adenocarcinomas arising from polypoid adenomas are now classified according to the Haggitt level of invasion [13][14][15][16]. In this sense, the current WHO classification of the IPNB is not satisfactory.…”

Pathology of premalignant colorectal neoplasia

“…Given that intramucosal carcinoma has virtually no potential for spread and given the difficulty distinguishing intramucosal carcinoma from high-grade dysplasia, many authorities favor discontinuing use of the term intramucosal adenocarcinoma completely. 46,47 Submucosal invasion by adenocarcinoma is defined by the presence of neoplastic glands that have penetrated through the muscularis mucosa into the submucosa, muscularis propria or serosa ( Fig. 3).…”

“…Therefore, intramucosal carcinomas require no additional treatment if the polyp has been entirely excised. Given that intramucosal carcinoma has virtually no potential for spread and given the difficulty distinguishing intramucosal carcinoma from high‐grade dysplasia, many authorities favor discontinuing use of the term intramucosal adenocarcinoma completely …”

Molecular Pathways and Cellular Metabolism in Colorectal Cancer

“…In fact, the evaluation of any adenoma or precancerous lesion (e.g. hyperplastic polyps, serrated adenoma or aberrant crypt foci) within the colorectum may be assessed by a number of techniques ranging from direct visualization through the endoscope, to microscopic assessment, and to evaluation at the molecular level [33]. Emerging knowledge of pathway-specific markers through the outlining of a molecular classification will likely be the basis for improved detection and diagnosis.…”