Shorter residual inferior mesenteric artery stump length on objective CT measurement is associated with improved oncological outcomes in rectal cancer surgery: A propensity score matched analysis.

Background
Studies have suggested little oncological benefit to 'high-tie' resection of the inferior mesenteric artery pedicle in rectal cancer surgery but have all been based on subjective surgical intent rather than objective, quantifiable measurements. In this study, we aimed to assess the level of transection objectively and investigate its influence on long-term oncological outcomes.Method
All patients undergoing elective resection for rectal cancer with curative intent between 2012 and 2020 in a tertiary referral centre were included. IMA stump length was measured on postoperative CT scan and patients categorised as having undergone 'high tie' (left colic artery absent and stump <40 mm) resection or 'low-tie' (left colic artery preserved or IMA stump >40 mm) resection. Propensity score matching was undertaken to produce comparable groups and multivariable regression modelling was performed pre- and post-matching. Principal outcome parameters were overall survival and local recurrence-free survival.Results
466 patients (mean 65.3 years, 33% female) were available for analysis. Mean (SD) IMA stump length was 18 (10) mm in the high-tie group and 47 (18) mm in the low-tie group respectively. After propensity score matching, two groups of 152 patients were compared. Multivariable survival analysis showed a significantly better overall (HR 1.84 [1.16-2.93], p = 0.010) and local recurrence-free (HR 2.23 [1.00-4.97], p = 0.049) survival for patients in the high-tie group.Conclusion
In contrast to other studies, our study has used objective measurements to show an association between central IMA transection and improved oncological outcomes. This association is preserved on multivariable analysis of the propensity score matched cohort.