Essential anatomy for total mesorectal excision and lateral lymph node dissection, in both trans-abdominal and trans-anal perspective

Reversed anatomy in transanal lateral lymph node dissection: landmarks and pitfalls

Lateral lymph node dissection (LLND) is getting global attention as an a surgical option to reduce local recurrence in locally advanced rectal cancer. As the transanal total mesorectal excision (TaTME) is gaining popularity worldwide, a novel LLND approach was established adopting a two-team approach that combines the transabdominal and transanal approaches using the TaTME technique. This narrative review describes the advantages, anatomical landmarks, surgical techniques, and pitfalls of transanal LLND (TaLLND). The advantages of TaLLND include a magnified view and enhanced maneuverability of the laparoscopic instruments in the deep pelvis. TaLLND is also beneficial for LLND in patients with a history of pelvic surgery because surgeons can have access to the areas unaffected by previous surgery. To master the TaLLND technique, the procedure should be understood according to the following steps: S4 nerve identification, lateral space entry, lateral dissection, obturator vein, artery, and nerve identification, dissection along the external iliac vein, medial dissection, median and bottom dissection, dissection along the internal iliac artery, and dissection along the obturator nerve. TaLLND can be applied to highly advanced disease that requires combined resection of the major internal iliac vessels, pelvic nerves, or adjacent organs. In such cases, simultaneous transanal and transabdomiinal LLND utilizing a two team approach has advantages as these approaches can provide mutual complementary roles. TaLLND is expected to overcome the difficulty of transabdominal LLND and improve the quality of LLND.

Dissection layer selection based on an understanding of pelvic fascial anatomy in transanal total mesorectal excision

This study aimed to review the historical transition of rectal cancer surgery and recent evidence regarding transanal total mesorectal excision (TaTME). Additionally, it outlined the anatomical landmarks and technical considerations essential for successful TaTME. Anatomical studies and surgical techniques were analyzed to identify key landmarks and procedural steps crucial for TaTME. TaTME offers improved visibility and maneuverability even in the deep and narrow pelvis and is expected to contribute to tumor radical cure rates. By securing the circumferential resection margin and distal margin while preserving pelvic autonomic nerve function, TaTME holds promise for maintaining postoperative urinary and sexual functions. Key anatomical landmarks include the endopelvic fascia posteriorly, the S4-pelvic splanchnic nerve laterally, and the prostate or posterior vaginal wall anteriorly. Selecting the appropriate dissection layer based on tumor depth and ensuring precise incision of the tendinous arch of the pelvic fascia contributes to successful TaTME outcomes. TaTME represents a significant advancement in rectal cancer surgery, offering improved outcomes through meticulous attention to anatomical detail and precise dissection techniques. Understanding the historical context of rectal cancer surgery alongside recent evidence on TaTME is essential for optimizing patient outcomes and expanding the safe implementation of this innovative approach.

Comparison of the short-term surgical outcomes of lateral lymph node dissection for low rectal cancer using a robotic-assisted transabdominal approach alone or supported by a transanal approach

BACKGROUND

Lateral lymph node metastases are a major cause of local recurrence after surgery for advanced low rectal cancer. Lateral lymph node dissection (LLND) may reduce the risk of local recurrence in patients with suspected lateral lymph node metastasis. Recent reports have shown that robotic-assisted LLND can help to reduce the postoperative complication rate, such as urinary disturbance. Furthermore, with the advent of transanal total mesorectal excision, a novel LLND procedure that combines a transabdominal approach with a transanal approach has been reported. This study aimed to clarify the safety and feasibility of robotic-assisted LLND supported by a transanal approach for advanced low rectal cancer.

METHODS

Thirty-nine patients diagnosed to have low rectal cancer between June 2019 and May 2023 were retrospectively enrolled and divided according to whether they underwent LLND via a robotic-assisted transabdominal approach alone (transabdominal group, n = 19) or in combination with a transanal approach (2team group, n = 20). The patient characteristics and short-term surgical outcomes were compared between the two groups.

RESULTS

The total operation time was significantly shorter in the 2team group than in the transabdominal group (366 min vs. 513 min, P < 0.001), as was the time taken to perform unilateral LLND (64 min vs. 114 min, P < 0.001). Furthermore, there was significantly less intraoperative bleeding in the 2team group (30 mL vs. 80 mL, P = 0.004). There was no significant between-group difference in postoperative complications. The incidence of postoperative urinary disturbance was satisfactory at 5% in both groups.

CONCLUSIONS

The operation time for LLND performed by a robotic-assisted transabdominal approach was shortened when supported by a transanal approach. The frequency of postoperative urinary disturbance was low in both groups. Therefore, robotic-assisted abdominal LLND supported by a transanal approach can be considered a promising treatment option for advanced low rectal cancer.

Essential anatomy for lateral lymph node dissection

In Western countries, the gold-standard therapeutic strategy for rectal cancer is preoperative chemoradiotherapy (CRT) following total mesorectal excision (TME), without lateral lymph node dissection (LLND). However, preoperative CRT has recently been reported to be insufficient to control lateral lymph node recurrence in cases of enlarged lateral lymph nodes before CRT, and LLND is considered necessary in such cases. We performed a literature review on aspects of pelvic anatomy associated with rectal surgery and LLND, and then combined this information with our experience and knowledge of pelvic anatomy. In this review, drawing upon research using a 3-dimensional anatomical model and actual operative views, we aimed to clarify the essential anatomy for LLND. The LLND procedure was developed in Asian countries and can now be safely performed in terms of functional preservation. Nonetheless, the longer operative time, hemorrhage, and higher complication rates with TME accompanied by LLND than with TME alone indicate that LLND is still a challenging procedure. Laparoscopic or robotic LLND has been shown to be useful and is widely performed; however, without a sufficient understanding of anatomical landmarks, misrecognition of vessels and nerves often occurs. To perform safe and accurate LLND, understanding the landmarks of LLND is essential.

Can the Single-stapling Technique Following Intersphincteric Resection with Transanal Total Mesorectal Excision Become the New Standard Anastomosis?

For transanal total mesorectal excision (TaTME), the indication for single-stapling technique (SST) has been expanded to include lower anastomosis, even in intersphincteric resection (ISR). We focused on the anastomotic techniques following ISR with TaTME and examined the feasibility and safety of the SST below the anorectal junction (ARJ). Data on postoperative anastomosis-related complications and anorectal function was evaluated in comparison to conventional manual hand-sewn coloanal anastomosis in ISR with TaTME. We examined patients with 3-6 cm tumors from the anal verge who underwent ISR with TaTME between January 2018 and March 2020, and whose anastomotic line was located below the ARJ. Postoperative short-term outcomes and anorectal functions were compared. We also analyzed the effects of various factors on major low anterior resection syndrome (LARS) using multivariate logistic regression analysis. In total, 87 patients-48 in the hand-sewn anastomosis group and 39 in the SST group-were included in this study. SST below the ARJ in ISR with TaTME did not exacerbate surgical outcomes, including anastomosis-related complications. The SST group had a significantly lower LARS score as compared to the hand-sewn anastomosis group, and the proportion of major LARS was significantly lower. Only hand-sewn anastomosis was identified as a statistically significant independent risk factor for major LARS. In TaTME, SST below the ARJ was safe and feasible and had a lower negative impact on postoperative anastomosis-related complications and anorectal function as compared to hand-sewn anastomosis. Thus, SST is a promising anastomotic option for patients with low-lying rectal tumors.

The Effectiveness and Safety of Rectal Modular Resection in Low Rectal Cancer: A Retrospective Study

Background: Described by Heald in 1982, total mesorectal excision (TME) is now routinely performed as the standard procedure for mid-low rectal cancer, with remarkable decrease in local recurrence and improved oncology outcome. However, the integrity of the resected mesentery and damage to autonomic nerves still remain challenging for general surgeons, especially in the cohort of neoadjuvant therapy patients. The concept of rectal modular resection (RMR), based on an integral understanding of the regional anatomy, was proposed as a surgical skill for dissociation of the rectum with shorter surgical duration, function preservation, and improved oncology outcome. Methods: This was a retrospective trial. Patients with resectable rectal lesions, ranging between 3 and 7 cm from the anal verge, were enrolled and grouped by TME surgery based on RMR or classical procedure resection (CPR). We estimated perioperative outcomes, including surgery complications such as anastomotic leak, urine retention, and others. Pathological properties, including distal clearance, harvested lymph nodes, tumor differentiation, and specimen grading, were also taken into account. Patients were followed postoperatively and functional evaluation was recorded at the 3-month and 1-year postoperation visits. Results: From January 2019 to December 2021, a total of 92 patients were enrolled in this study. TME surgery complying with the RMR methodology was performed with a back-to-bilateral-to-front modular proceeding. Duration of operation was significantly shortened in the RMR group, without increase in blood loss or failure rate of anus preservation. The quality of the specimen, graded according to integrity of the mesorectum, stands out in the RMR group. Functional evaluation revealed no statistical difference between RMR and CPR groups regarding sexual ability impairment and defecation disorder since follow-up is still ongoing. Conclusions: RMR-based TME was efficient with compressed operation duration compared with CPR and its safety was well validated with regard to the occurrence of complications and function loss.

Synchronous Colorectal Liver Metastases considering Infectious Complications: Simultaneous or Delayed Surgery?

Background

Simultaneous or delayed surgery for synchronous colorectal liver metastases is performed in the clinic; which method is better is still up for debate. In particular, infectious complications are rarely compared. This study aims to investigate the differences between simultaneous and delayed surgery for synchronous colorectal liver metastases by comparing infectious complications and prognosis.

Methods

Firstly, the patients' information from a single institution's database was retrospectively analyzed. Then the patients were divided into a simultaneous group and a delayed group according to synchronous colorectal liver metastases. Analyzing the postoperative complications within 30 days, the progression-free survival, and the overall survival in the two groups.

Results

The simultaneous group had a higher neo-adjuvant chemotherapy rate (42.0% VS. 16.0% in the delayed group, P < 0.05) and laparoscopic surgery rate (89.8% VS. 72.0% in the delayed group, P < 0.05) than the delayed group. Moreover, the simultaneous group had a higher liver-related infection rate (17.0 VS. 0.0% in the delayed group, P < 0.05).

Conclusion

Although there was no difference in survival rate between delayed and simultaneous surgeries, the delayed surgery have fewer liver-related infections compared with the simultaneous surgery in synchronous colorectal liver metastases patients. Delayed surgery could be a better treatment method for synchronous colorectal liver metastases patients.