Patologìâ (Aug 2016)
Serrated polyps as precursor lesions of colorectal cancer: current status and future directions. Mini-review.
Abstract
Early diagnosis of colorectal cancer (CRC) is a very urgent problem, since this disease has second place among women and the third one among men in the structure of cancer pathology. According to recent data, CRC should be considered as a heterogeneous multifactorial family of diseases with different variants. Serrated polyps of the colon are obligate precancerous condition, which can transform into cancer due to genetic aberrations. Serrated polyps are a heterogeneous group of formations with different ways of appearance and potential malignancy. They are divided into major subtypes: hyperplastic polyps, sessile serrated adenoma/polyp and traditional serrated adenoma. The purpose of the study was the analysis of current data about mechanisms of formation and malignization of serrated colonic polyps. The relationship between the localization of serrated polyps and their morphology was identified. Polyps located in the proximal colon are characterized by a more expressed degree of serration in the basal segment of crypts compared with polyps located in the distal part of the colon. The difference between the proximal and distal localization was confirmed by molecular genetic testing: the majority of proximal serrated polyps develops after BRAF mutations, and the majority of polyps with distal localization develops after a KRAS mutation. It is known that a key role in the excessive proliferation and inhibition of apoptosis in the process of malignant transformation of serrated polyps is provided by the combination of different types of genome damage, both genetic and epigenetic. Molecular changes are already present in the early stages of cell dysplasia in serrated colon polyps, and their nature determines the malignant potential. Conclusions. A thorough study of the molecular mechanisms of progression along the serrated pathway and transformation of serrated polyps in the CRC opens up prospects for the development of guidelines for patient management in order to prevent the development of serrated pathway cancers.
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