Abstract: Risk factors for positive pathological circumferential resection margin after transanal total mesorectal excision: a nationwide registry study with 805 cases of rectal cancer        YAO Hong-wei*，ZHANG Hong-yu，REN Ming-yang, et al. On behalf on the research team of Chinese Transanal Total Mesorectal Excision Registry Collaborative. *Department of General Surgery，Beijing Friendship Hospital，Capital Medical University，& National Clinical Research Center for Digestive Diseases，Beijing 100050,China
Corresponding author：ZHANG Zhong-tao，E-mail：zhangzht@ccmu.edu.cn
YAO Hong-wei, ZHANG Hong-yu, REN Ming-yang, CHEN Chien-Chih, XU Qing, and WANG Quan are the first authors who contributed equally to the article
Abstract    Objective    The purpose of this study is to analyze the clinical and pathological data of patients underwent transanal total mesorectal excision (taTME) and registered in the Chinese taTME Registration Collaborative (CTRC) database, and to explore the risk factors for positive pathological circumferential resection margin (CRM). Methods    Based on the CTRC database, taTME cases from 40 centers nationwide from May 2010 to November 2019 were analyzed. The risk factors for positive pathological CRM after taTME procedure was explored. Results    805 cases were selected and included in this study. The median age was 62 (24-88) years, the median BMI was 23.6 (15.8-45.8) kg/m2. 318 cases (42.4%) were performed simultaneously by abdominal team and transanal team, the median operation time was 220 (90-630) minutes. The incidence of anastomotic leakage was 5.9%. The positive rate of CRM and distal resection margin were 2.7% and 0.9% respectively. The median number of lymph nodes harvest was 14 (0-51). Univariate analysis showed that preoperative MRI identified T4 tumor, EMVI positive, threatened MRF, and the experience of participating in the first taTME structured training in China were associated with positive pathological CRM. Conclusion    The preoperative rectal MRI evaluation for taTME cases has great predictive value for positive pathological CRM, and the standardized postoperative pathological report of taTME needs to be promoted. The quality of the CTRC data still needs improving, and the structured training of taTME procedure is indispensable.

Key words: rectal cancer；transanal total mesorectal excision (taTME)；circumferential resection margin (CRM), Chinese Transanal Total Mesorectal Excision Registry Collaborative (CTRC)；structured training

摘要： 目的    分析登记于中国经肛全直肠系膜切除（taTME）病例登记协作研究数据库（CTRC）的taTME病例的临床病理学资料，探讨直肠癌taTME术后病理标本环周切缘（CRM）阳性危险因素。方法    分析自2010年5月至2019年11月期间，来自全国40个中心登记录入CTRC的taTME病例，评估直肠癌taTME术后病理标本环周切缘阳性危险因素。结果    共计805例直肠癌taTME手术病例纳入研究，其中男556例（69.1%），年龄中位数为62（24~88）岁，BMI中位数为23.6（15.8~45.8）；318例（42.4%）taTME手术由经腹经肛两组外科医师同时进行，手术时间中位数为220（90~630）min。吻合口漏发生率为5.9%；手术标本CRM阳性率为2.7%，远端切缘阳性率为0.9%，淋巴结清扫数目中位数为14（0~51）枚；单因素分析显示术前MRI评估为T4、壁外血管侵犯（EMVI）阳性、直肠系膜筋膜（MRF）受侵、术者中心参加第一次taTME结构化培训，为CRM阳性的危险因素。结论    taTME术前直肠MRI评估项目对于术后病理标本CRM阳性有预测意义，需要推行直肠癌taTME术后病理检查报告的标准化；CTRC数据质量仍须改善，taTME手术结构化培训不可或缺。

关键词: 直肠癌, 经肛全直肠系膜切除术, 环周切缘, 中国taTME病例登记协作研究数据库, 结构化培训