Serrated colonic polyps: dispelling myths

Excerpt

The important recent article, “Serrated polyps at CT colonography: prevalence and characteristics of the serrated polyp spectrum” by Kim et al. in Radiology, highlights an important change in our understanding of colorectal cancer and in the interpretation of CT colonography examinations [1]. In the past, it was believed that the vast majority of colon cancers arose from pre-existing adenomatous polyps (the adenoma–carcinoma sequence) [2]. The pathway for developing these lesions, through a series of mutations and molecular changes, is well established [2]. For radiologists, the implications were to detect adenomatous polyps of biologic importance (those over 5 mm in diameter), and refer those patients for polypectomy. The potential to eradicate colorectal cancer via this mechanism was believed to be achievable through a host of public health initiatives aimed at regular screening of the public beginning at age of 50 (including barium enema and CT colonography). Evidence now exists that the benefits of colonoscopic screening are mainly focused on the left colon, with little reduction in mortality rates from right-sided colon cancers [3]. The reasons for this may be multifactorial including incomplete colonoscopy, incomplete lesion removal, missed lesions due to suboptimal colonoscopy techniques, and sessile serrated polyps [4]. Serrated polyps are the “new kid” on the block—and our understanding of these lesions is changing colorectal cancer screening in potentially important ways. …