Effect of ligation sequence of the inferior mesenteric artery and vein on circulating tumour cells and survival in minimally invasive rectal cancer surgery: study protocol for a randomised controlled trial (ARVECTS study).

[INTRODUCTION] Total mesorectal excision has been adopted as standard procedure for resectable rectal cancer. However, there is no regulation in the current guidelines on the sequence of ligation of the inferior mesenteric artery and vein during rectal cancer surgery owing to a lack of sufficient evidence. Circulating tumour cells (CTCs) in peripheral blood can be used as potential indicators for predicting postoperative recurrence and prognosis in patients with colorectal cancer. The aim of the study is to investigate whether vascular ligation sequence affects the dissemination of CTCs into the bloodstream and survival during minimally invasive rectal cancer surgery.

[METHODS AND ANALYSIS] This study is a prospective, multicentre, randomised controlled trial investigating the effect of ligation sequence (inferior mesenteric artery vs vein priority) on CTC levels and survival outcomes in minimally invasive rectal cancer surgery. 268 eligible patients with rectal cancer will be randomly assigned to the priority ligation of the inferior mesenteric vein group or priority ligation of the inferior mesenteric artery group during minimally invasive rectal cancer surgery. The primary endpoint of this study is the change of peripheral blood CTC levels before and after surgery, analysed using the Wilcoxon rank sum test. Secondary endpoints are 3-year disease-free survival, 3-year overall survival, 3-year recurrence pattern, intraoperative blood loss, operation duration, conversion rate, number of lymph nodes collected, intraoperative morbidity and mortality, postoperative morbidity and mortality and postoperative recovery course.

[ETHICS AND DISSEMINATION] The study has been approved by the ethics committee of Sichuan Cancer Hospital (Approval number: SCCHEC-02-2024-102), all participants of the study will be well informed and written informed consent will be obtained from all participants. Findings from this trial will be published in peer-reviewed publications.

[TRIAL REGISTRATION NUMBER] NCT05807646.