恶性息肉通过检查组织学特征评估未切除肠道中残留肿瘤并指导外科手术决策。其中最重要的特征之一是切除边缘的涉及情况，但最佳的边缘涉及定义尚未知晓。本研究旨在研究三种不同定义并确定它们对临床结果的影响。鉴定了165个通过内窥镜切除的恶性息肉，并将其组织学特征与随后的外科手术复查或经过一段时间的临床随访后的肿瘤复发进行相关性分析。癌肿在息肉边缘涉及被定义为三种不同的方式，并进行结果比较。肿瘤复发与肿瘤分级、粘液性组织学和切除边缘涉及有关。所有三种边缘涉及定义可将息肉分为临床上显著的类别；然而，当涉及定义为息肉基底处的凝固伪影区内有肿瘤或边缘处存在肿瘤时，1毫米的边缘被认为是“高风险”的73％，而使用1毫米边缘涉及定义则为59.1％。所有三种“低风险”组的局部复发率均<6.5％。在结肠和直肠内窥镜切除的恶性息肉的边缘涉及定义在医疗保健系统之间存在差异，但欧洲和北美普遍使用1毫米间隙。我们的结果表明，1毫米间隙是不必要的，应该用基于边缘或凝固伪影区内的肿瘤的定义来替代它。©2023 John Wiley＆Sons Ltd.

Malignant polyps are examined to assess histological features which predict residual tumour in the unresected bowel and guide surgical decision-making. One of the most important of these features is resection margin involvement, although the best definition of margin involvement is unknown. In this study we aimed to investigate three different definitions and determine their impact on clinical outcomes.One hundred and sixty-five malignant polyps removed endoscopically were identified and histological features correlated with either residual tumour in subsequent surgical resections or tumour recurrence following a period of clinical follow-up. Involvement of the polyp margin by cancer was defined in three different ways and outcomes compared. Tumour recurrence was associated with tumour grade, mucinous histology and resection margin involvement. All three definitions of margin involvement separated polyps into clinically significant categories; however, a margin ≤ 1 mm identified 73% of polyps as 'high-risk' compared with 59.1% when involvement was defined as tumour within the zone of coagulation artefact at the polyp base or 50% when tumour was present at the margin. All three 'low-risk' groups had a locoregional recurrence rate < 6.5%.Definitions of margin involvement for endoscopically removed malignant polyps in the colon and rectum vary between health-care systems, but a 1-mm clearance is widely used in Europe and North America. Our results suggest that a 1-mm margin is unnecessary and should be replaced by a definition based on tumour at the margin or within coagulation artefact at the polyp base.© 2023 John Wiley & Sons Ltd.