sigmoid突起定义的引入可能会导致从直肠癌转向乙状结肠癌。这项回顾性队列研究旨在确定新定义的临床影响。在这项多中心的回顾性队列研究中，如果患者在2015年1月至2017年12月之间接受了针对非转移性直肠癌的选择性根治性全直肠系膜切除手术，根据以前的定义在荷兰结肠直肠癌登记处注册为直肠癌，并且存在MRI报告，就会纳入患者。所有经筛选的直肠癌病例都将使用sigmoid突起定义进行重新评估。主要结果是重新评估为乙状结肠癌的患者数量。次要结果包括新定义的直肠癌和乙状结肠癌患者在治疗、围手术期结果以及3年肿瘤学结果（总生存期、无疾病生存期、局部和全身复发）方面的差异。在1742名符合条件的患者中，共有1302名直肠癌患者被纳入研究。其中，170名（13.1%）被重新分类为乙状结肠癌。其中，93名患者（54.7%）根据荷兰指南会被提供其他辅助治疗或新辅助治疗。重新评估后出现乙状结肠肿瘤的患者具有更低的30天术后并发症发生率（33.5%比48.3%，P <0.001）、更低的再次干预率（8.8%比17.4%，P <0.007）和更短的住院时间（5天（IQR 4-7）中位数对比6天（IQR 5-9），P <0.001）。3年肿瘤学结果相当。使用乙状结肠突起的解剖标志，之前被分类为直肠癌的13.1%的患者被重新分类为乙状结肠癌，其中54.7%的患者在新辅助治疗或辅助治疗方面将接受不同的治疗策略。©2023年作者。由牛津大学出版社代表BJS Society Ltd出版。

The introduction of the sigmoid take-off definition might lead to a shift from rectal cancers to sigmoid cancers. The aim of this retrospective cohort study was to determine the clinical impact of the new definition.In this multicentre retrospective cohort study, patients were included if they underwent an elective, curative total mesorectal excision for non-metastasized rectal cancer between January 2015 and December 2017, were registered in the Dutch Colorectal Audit as having a rectal cancer according to the previous definition, and if MRI was available. All selected rectal cancer cases were reassessed using the sigmoid take-off definition. The primary outcome was the number of patients reassessed with a sigmoid cancer. Secondary outcomes included differences between the newly defined rectal and sigmoid cancer patients in treatment, perioperative results, and 3-year oncological outcomes (overall and disease-free survivals, and local and systemic recurrences).Out of 1742 eligible patients, 1302 rectal cancer patients were included. Of these, 170 (13.1 per cent) were reclassified as having sigmoid cancer. Among these, 93 patients (54.7 per cent) would have been offered another adjuvant or neoadjuvant treatment according to the Dutch guideline. Patients with a sigmoid tumour after reassessment had a lower 30-day postoperative complication rate (33.5 versus 48.3 per cent, P < 0.001), lower reintervention rate (8.8 versus 17.4 per cent, P < 0.007), and a shorter length of stay (a median of 5 days (i.q.r. 4-7) versus a median of 6 days (i.q.r. 5-9), P < 0.001). Three-year oncological outcomes were comparable.Using the anatomical landmark of the sigmoid take-off, 13.1 per cent of the previously classified patients with rectal cancer had sigmoid cancer, and 54.7 per cent of these patients would have been treated differently with regard to neoadjuvant therapy or adjuvant therapy.© The Author(s) 2023. Published by Oxford University Press on behalf of BJS Society Ltd.