Serrated Polyps: Critical Precursors to Colorectal Cancer
Serrated Polyps: Critical Precursors to Colorectal Cancer
Colorectal polyps have been traditionally classified as either hyperplastic or adenomatous, with only the latter progressing to carcinoma. However, it is now recognized that certain subtypes of serrated polyps have a risk of malignant transformation via a serrated neoplasia pathway. Serrated polyps are a heterogeneous group of lesions with distinct morphologic, histologic and molecular genetics profiles. Based on available evidence, there are reasons to suspect that this pathway may contribute to interval or missed cancers because serrated lesions are more likely than conventional adenomas to be missed on colonoscopy, and the progression of serrated polyps to cancer may be more rapid. Therefore, it is paramount that physicians recognize the importance of serrated polyps and are aware of the latest surveillance guidelines.
Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy, with approximately 150,000 new cases diagnosed annually in the USA. Nearly all cases of CRC originate from identifiable precursor lesions. Traditionally, colorectal epithelial polyps were classified as either hyperplastic or adenomatous polyps. Hyperplastic polyps were defined as having serrated crypts without dysplasia, whereas adenomas were nonserrated and contained dysplastic epithelium. The adenomatous polyp was believed to represent the precursor lesion for most CRCs. However, it is now recognized that alternative pathways to CRC exist via distinct types of serrated polyps. In this article, we review the classification of serrated polyps, evidence for a serrated CRC pathway, risk factors for serrated polyps and clinical implications.
Abstract and Introduction
Abstract
Colorectal polyps have been traditionally classified as either hyperplastic or adenomatous, with only the latter progressing to carcinoma. However, it is now recognized that certain subtypes of serrated polyps have a risk of malignant transformation via a serrated neoplasia pathway. Serrated polyps are a heterogeneous group of lesions with distinct morphologic, histologic and molecular genetics profiles. Based on available evidence, there are reasons to suspect that this pathway may contribute to interval or missed cancers because serrated lesions are more likely than conventional adenomas to be missed on colonoscopy, and the progression of serrated polyps to cancer may be more rapid. Therefore, it is paramount that physicians recognize the importance of serrated polyps and are aware of the latest surveillance guidelines.
Introduction
Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy, with approximately 150,000 new cases diagnosed annually in the USA. Nearly all cases of CRC originate from identifiable precursor lesions. Traditionally, colorectal epithelial polyps were classified as either hyperplastic or adenomatous polyps. Hyperplastic polyps were defined as having serrated crypts without dysplasia, whereas adenomas were nonserrated and contained dysplastic epithelium. The adenomatous polyp was believed to represent the precursor lesion for most CRCs. However, it is now recognized that alternative pathways to CRC exist via distinct types of serrated polyps. In this article, we review the classification of serrated polyps, evidence for a serrated CRC pathway, risk factors for serrated polyps and clinical implications.
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