Localization of mesenteric lymph node metastases in relation to the level of arterial ligation in rectal cancer surgery

For oncological reasons, central arterial ligation of the inferior mesenteric artery (IMA) is suggested in rectal cancer surgery although no conclusive evidence support this. We have therefore investigated the localization of lymph node metastases and compared central ligation of the IMA versus peripheral arterial ligation, in rectal cancer specimens. This was a cross-sectional population-based study of consecutive recruited patients who underwent resection for rectal cancer in 2012–2015. Multiple linear regression analysis was used to explore the relationship between lymph node count and age, sex, body mass index, preoperative oncological treatment, type of surgery, tumour stage, and vessel and specimen length. 151 patients (54 women) were included, with median (range) age 70 (45–87) years. The median (range) number of lymph nodes retrieved was 25 (3–70), which was associated with body mass index, type of surgery and vessel length. Vessel length, median (range) 9.6 (5–14) and 9.2 (5–15) cm for reported central and peripheral arterial ligation, respectively, was associated with body mass index. In 39 of 42 samples, metastatic lymph nodes were located in the mesorectum, and 13 of 42 samples also had metastatic lymph nodes in the sigmoid mesentery. None were found around the ligated artery. To recruit all metastatic lymph nodes in rectal cancer surgery, it is important to include the sigmoid mesentery in the specimen, but not to perform a central ligation of the IMA compared with ligation of the SRA close to the left colic artery (LCA).