Division of Gastroenterology and Hepatology, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
Department of Pathology, Radboud University Medical Centre, Nijmegen, The Netherlands.
Gastroenterology. 2019 Oct;157(4):949-966.e4. doi: 10.1053/j.gastro.2019.06.041. Epub 2019 Jul 16.
In addition to the adenoma to carcinoma sequence, colorectal carcinogenesis can occur via the serrated pathway. Studies have focused on clarification of categories and molecular features of serrated polyps, as well as endoscopic detection and risk assessment. Guidelines from the World Health Organization propose assigning serrated polyps to categories of hyperplastic polyps, traditional serrated adenomas, and sessile serrated lesions (SSLs). Traditional serrated adenomas and SSLs are precursors to colorectal cancer. The serrated pathway is characterized by mutations in RAS and RAF, disruptions to the Wnt signaling pathway, and widespread methylation of CpG islands. Epidemiology studies of serrated polyps have been hampered by inconsistencies in terminology and reporting, but the prevalence of serrated class polyps is 20%-40% in average-risk individuals; most serrated polyps detected are hyperplastic. SSLs, the most common premalignant serrated subtype, and are found in up to 15% of average-risk patients by high-detecting endoscopists. Variations in rate of endoscopic detection of serrated polyps indicate the need for careful examination, with adequate bowel preparation and sufficient withdrawal times. Risk factors for SSLs include white race, family history of colorectal cancer, smoking, and alcohol intake. Patients with serrated polyps, particularly SSLs and traditional serrated adenomas, have an increased risk of synchronous and metachronous advanced neoplasia. Surveillance guidelines vary among countries, but SSLs and proximal hyperplastic polyps require special attention in assignment of surveillance interval-especially in light of concerns regarding incomplete detection and resection.
除了腺瘤到癌序列，结直肠发生也可以通过锯齿途径发生。研究重点在于阐明锯齿状息肉的类别和分子特征，以及内镜检测和风险评估。世界卫生组织的指南建议将锯齿状息肉分为增生性息肉、传统锯齿状腺瘤和无蒂锯齿状病变（SSL）。传统锯齿状腺瘤和 SSL 是结直肠癌的前体。锯齿途径的特征是 RAS 和 RAF 突变、Wnt 信号通路中断以及 CpG 岛广泛甲基化。锯齿状息肉的流行病学研究受到术语和报告不一致的阻碍，但在平均风险个体中，锯齿状类息肉的患病率为 20%-40%；大多数检测到的锯齿状息肉为增生性息肉。SSL 是最常见的癌前锯齿状亚型，在高检出内镜医师中，在高达 15%的平均风险患者中发现。锯齿状息肉内镜检测率的差异表明需要仔细检查，充分的肠道准备和足够的退出时间。SSL 的危险因素包括白种人、结直肠癌家族史、吸烟和饮酒。有锯齿状息肉的患者，尤其是 SSL 和传统锯齿状腺瘤，具有同步和异时性高级别肿瘤的风险增加。不同国家的监测指南不同，但 SSL 和近端增生性息肉需要特别注意监测间隔的分配，特别是考虑到对不完全检测和切除的担忧。
