Anastomotic leakage is a common and serious postoperative complication in patients with rectal cancer, with an incidence of 5–20%[23–25], and the mortality rate after anastomotic leakage can be as high as 16%.[26–28] Anastomotic leakage not only affects the postoperative recovery of patients, the medical costs, but also increases the local recurrence and decreases the overall survival rate. Once the anastomotic leakage occurs, both the patient and the doctor will pay a huge price in the process of treatment. Therefore, surgeons are doing what they can do to prevent anastomotic leakage after rectal cancer surgery.
Many risk factors have been revealed for anastomotic leakage after rectal cancer surgery including male, obese, malnutrition, preoperative chemoradiotherapy, and diabetes, etc. However, the insufficient blood perfusion and technical factors are still considered to be the key factors in the development of anastomotic leakage [29, 30]. Blood supply at the proximal end of the anastomosis after high ligation of IMA is only from the marginal artery, which may lead to insufficient anastomotic perfusion, especially in elderly patients and atherosclerosis patients. Dworkin et al. and Seike et al. concluded that high ligation of IMA interrupted the blood supply of LCA, and the blood supply to the proximal colon of the anastomosis was only dependent on the marginal artery, thus significantly reduces blood flow to the proximal colon of anastomosis[18, 31]. If the LCA is preserved during anterior resection for rectal cancer, the blood supply of the anastomosis is derived from the dual supply of the marginal artery and the LCA, thus may contributing to increased blood perfusion of anastomosis and reducing the incidence of anastomotic leakage.
Yang, X et al. suggested that preservation of LCA resulted in a significantly decreased incidence of anastomotic leakage. Our study revealed that the incidence of anastomotic leakage was significantly lower in the LCA preservation group than in that of the non-preservation of the LCA group, which was consistent with the previous studies. In contrast, Fujii S et al. found that the level of IMA ligation does not significantly influence the incidence of anastomotic leakage. The total number of harvested LNs and the number of positive LNs show no differences between the two groups, which was similar to the results of previous study[33, 34]. Furthermore, previous studies have confirmed that low ligation of IMA in laparoscopic anterior resection for rectal cancer reduces genitourinary dysfunction. However, this outcome was not observed in this study, possibly because dissection of the IMA root LNs inevitably injured the superior hypogastric plexus.
The type of IMA and its position relationship with LCA varies among individuals[22, 36], may lead to the blindness of intraoperative dissection of IMA and LCA. The preservation of LCA during anterior resection for rectal cancer requires exposing IMA and LCA, which if of technical difficulties. Thus, preoperative evaluation of the IMA type based on three-dimensional CT reconstruction results is beneficial[15, 37]. In this study, the IMA of 108 patients was divided into four types according to the three-dimensional CT reconstruction image. Furthermore, the position relationships of LCA, SA and SRA can be obtained by three-dimensional CT reconstruction. If preoperative three-dimensional CT reconstruction results indicates absence of LCA, high ligation of IMA should be performed without the need to expose LCA. However, preservation of the LCA cannot be mechanically performed according to IMA types. Personalized surgical strategies should be adopted to combine the IMA types, IMA length and the position relationship among LCA, SA, and SRA obtained by three-dimensional CT reconstruction image before surgery, which can be of guiding value for the preservation of LCA during rectal cancer surgery. Previous study have shown that robotic low ligation of the IMA with real-time identification of the vascular system for rectal cancer using the firefly technique is safe and feasible, which facilitate the identification of the branch of the IMA. This technique can provide navigation for the exposure and ligation of vascular, which is of great value for accurate and safe implemented IMA root lymph node dissection combine with the preservation of the LCA. It has been reported that the LCA ascended to the splenic flexure together with the IMV in 71.4% patients. Because of this anatomical structure, the LCA may be injured or cut off when IMV is exposed during rectal cancer surgery and the purpose of preserving LCA may not be achieved. Preoperative three-dimensional CT and intraoperative fluorescence imaging can provide guidance for surgeons in the treatment of LCA and IMV during rectal cancer surgery. However, high-quality randomized controlled studies are needed to further confirm whether the use of these two techniques will reduce intraoperative vascular injury, blood loss and operative time.
This single-center prospective cohort study has several limitations. Preservation of the LCA during anterior resection for rectal cancer has not been widely carried out in our department, so the sample accumulation is slow and the sample size is small. This study was a non-randomized controlled trial, which affected the reliability of the results at least to some extent. Due to insufficient follow-up time, this study did not compare the oncology efficacy and long-term prognosis between the two groups. Postoperative functions, such as defecation, postoperative exhaust recovery, sexual function, bladder function, and postoperative quality of life, were not evaluated in this study. To overcome these limitations, further multi-center, large-sample, randomized controlled trials are needed.