Radiologic Factors and Areas of Local Recurrence in Locally Advanced Lower Rectal Cancer After Lateral Pelvic Lymph Node Dissection

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.

Risk factors for local recurrence in patients with clinical stage II/III low rectal cancer: A multicenter retrospective cohort study in Japan

Background

Identifying risk factors for local recurrence (LR) is pivotal in optimizing rectal cancer treatment. Total mesorectal excision (TME) and lateral lymph node dissection (LLND) are the standard treatment for advanced low rectal cancer in Japan. However, large-scale studies to evaluate risk factors for LR are limited.

Methods

Data from 1479 patients with clinical stage II/III low rectal cancer below the peritoneal reflection, surgically treated between January 2010 and December 2011 across 69 hospitals, were analyzed. Fine-Gray multivariable regression modeling was used to identify risk factors associated with LR. Two models were developed: one using preoperative factors only, and the other incorporating operative and postoperative factors.

Results

Across the entire cohort, the 5-year cumulative incidence of LR was 12.3% (95% confidence interval, 10.7-14.1). The multivariable analysis associated LR with various preoperative (body mass index, distance from anal verge, cN category, and histological subtype), treatment-related (neoadjuvant therapy, and LLND), and postoperative (pT, pN, and resection margins) risk factors. For patients without neoadjuvant treatment, LR risk was unacceptably high with two or three preoperative risk factors (body mass index ≥25 kg/m2, distance from anal verge ≤4.0 cm, non-well/moderately differentiated adenocarcinoma). The 5-year cumulative incidence of LR was 24.7% in patients treated without LLND and 22.9% in patients treated with LLND.

Conclusion

This large multicenter cohort study identified some risk factors for LR in the setting where upfront TME was predominant, offering insights to optimize rectal cancer treatment.

The diagnosis and oncological outcomes of obturator and internal iliac lymph node metastasis in middle-low rectal cancer: results of a multicenter Lateral Node Collaborative Group study in China

BACKGROUND

Lateral lymph node dissection (LLND) can decrease local recurrence to lateral compartments in middle-low rectal cancer, but pathological evidence for optimal surgical indications, especially after neoadjuvant (chemo)radiotherapy (nCRT), is lacking. This study aimed to identify the predictive factors and oncological outcomes for different LLN locations associated with pathological metastasis.

METHOD

In this multicenter study, patients from 19 centers who underwent total mesorectal excision (TME) with LLND for locally advanced mid-/low rectal cancer from January 2012 to December 2021 were included.

RESULTS

All 566 included patients underwent TME with LLND surgery; 241 (37.4%) of the largest LLNs were located in the obturator area, and 403 (62.6%) of the largest LLNs were located in the internal iliac area. Multivariate analysis revealed that a short-axis size of 9 mm for the obturator area and 6 mm for internal iliac nodes constituted a reliable indicator of pathological LLN metastasis in non-CRT patients. In nCRT patients, a short-axis node size of 7 mm for obturator nodes and 4 mm for internal iliac nodes could be used to accurately predict pathological LLN metastasis. In contrast to pathological internal iliac node metastasis, pathological obturator node metastasis was associated with lower distant metastasis-free survival (DMFS) (P = 0.001), cancer-specific survival (CSS) (P = 0.043), and overall survival (OS) (P = 0.009), but lower lateral local recurrence-free survival (LRFS) (P > 0.05) was not statistically significant.

CONCLUSIONS

The obturator and internal iliac nodes may be two completely different types of LLNs, and the optimal cutoff value for predicting pathological LLN metastasis is inconsistent regardless of nCRT. Clinical trial registration The protocol of the current study was registered on ClinicalTrials.gov (NCT04850027), and the protocols were in accordance with the standards set by the World Medical Association Declaration of Helsinki.

Cross-sectional investigation of the distribution characteristics and prognostic significance of lateral lymph nodes in patients with rectal cancer

BACKGROUND

Information about the distribution characteristics and prognostic significance of lateral lymph nodes (LLNs) on primary computed tomography (CT) scan in rectal cancer patients is lacking.

METHODS

Between January 2013 and December 2016, patients with pathologically proved rectal cancer and pretreatment abdominal enhanced CT in our department were screened. We firstly redivided LLNs into seven categories based on their locations. Then, the number and distribution of all measurable LLNs and the characteristics of the largest LLN in each lateral compartment were recorded. Furthermore, we investigated the long-term outcomes in patients with different LLN characteristics and LLN risk scoring.

RESULTS

A total of 572 patients were enrolled in this study. About 80% of patients had measurable LLNs, and most patients developed measurable LLNs in the obturator cranial compartment. Lateral local recurrence (LLR) was observed in 20 patients, which accounted for 83.3% of the local recurrence (LR). Patients with the largest LLN short-axis diameter >10 mm had a poor prognosis, which was similar to that in patients with simultaneous distant metastasis (SDM). Patients with LLN risk scoring ≥2 had a worse prognosis than those with LLN risk scoring <2, while better than those with SDM.

CONCLUSION

This study suggests that LLR is the main locoregional recurrence pattern. Most rectal cancer patients have measurable LLNs on primary CT scan. However, patients with enlarged LLNs <10 mm or LLN risk scoring <2 still have a significantly better prognosis than patients with SDM, which indicated the potential value of locoregional treatment for these LLNs.

Management of internal iliac and obturator lymph nodes in mid-low rectal cancer

In rectal cancer treatment, the diagnosis and management of lateral pelvic lymph nodes (LLN) are critical for preventing local recurrence. Over time, scholars have reached a consensus: when imaging suggests LLN metastasis, combining neoadjuvant chemoradiotherapy (nCRT) with selective LLN dissection (LLND) can mitigate the risk of recurrence. Selective LLND typically encompasses lymph nodes in the internal iliac and obturator regions. Recent studies emphasize distinctions between internal iliac and obturator lymph nodes regarding prognosis and treatment outcomes, prompting the need for differentiated diagnostic and treatment approaches.

Two-Team Transanal Total Mesorectal Excision and En Bloc Resection of the Lateral Pelvic Lymph Nodes, Main Iliac Vessels, and Pelvic Plexus for Locally Advanced Rectal Cancer With Lateral Lymph Node Metastasis

BACKGROUND

Here, we describe the precise surgical technique for a novel procedure involving 2-team transanal total mesorectal excision with en bloc lateral pelvic lymph node (LPLN) dissection combined with resection of the involved main internal iliac vessels and pelvic plexus.

METHODS

From September 2020 to May 2023, 4 patients underwent the procedure at our hospital.

RESULTS

The operation time and blood loss were 272 to 412 minutes and 10 to 124 mL, respectively. No patients required conversion to open surgery or exhibited Clavien-Dindo grade III or worse postoperative complications, although 2 developed grade II urinary dysfunction. All surgical margins were negative.

CONCLUSIONS

Our novel 2-team method can facilitate safe and satisfactory surgery, even for highly advanced rectal cancer. The transanal approach offers excellent visibility and operability, even during LPLN and adjacent structure dissection. Furthermore, initial dissection of the distal branches of the iliac vessels prevents excessive lymphatic tissue congestion, facilitating easier, and clearer dissection.

Optimization of treatment strategies based on preoperative imaging features and local recurrence areas for locally advanced lower rectal cancer after lateral pelvic lymph node dissection

Purpose

Local recurrence (LR) is the main cause of treatment failure in locally advanced lower rectal cancer (LALRC). This study evaluated the preoperative risk factors for LR in patients with LALRC to improve the therapeutic strategies.

Patients and Methods

LALRC patients who underwent total mesorectal excision (TME) with lateral pelvic lymph node (LPN) dissection (LPND) from January 2012 to December 2019 were reviewed. The log-rank test was used to assess local recurrence-free survival (LRFS), and multivariate Cox regression was used to identify the prognostic risk factors for LRFS. Follow-up imaging data were used to classify LR according to the location.

Results

Overall, 376 patients were enrolled, and 8.8% (n=33) of these patients developed LR after surgery. Multivariate analysis identified positive clinical circumferential resection margin (cCRM) as an independent prognostic factor for LRFS (HR: 4.94; 95% CI, 1.75-13.94; P=0.003). The most common sites for LR were the pelvic plexus and internal iliac area (PIA) (54.5%), followed by the central pelvic area (CPA) (39.4%) and obturator area (OA) (6.1%). Following a subgroup analysis, LR in the OA was not associated with positive cCRM. Patients treated with upfront surgery (n=35, 14.1%) had a lower cCRM positive rate when compared with patients treated with neoadjuvant chemoradiotherapy (nCRT) (n=12, 23.5%). However, the LR rate in the nCRT group was still lower (n=28, 36.4%) than that in the upfront surgery group (n=35, 14.%). Among patients with positive cCRM, the LR rate in patients with nCRT remained low (n=3, 10.7%).

Conclusion

Positive cCRM is an independent risk factor for LR after TME plus LPND in LALRC patients. LPND is effective and adequate for local control within the OA regardless of cCRM status. However, for LALRC patients with positive cCRM, nCRT should be considered before LPND to further reduce LR in the PIA and CPA.

Two-team lateral lymph node dissection assisted by the transanal approach for locally advanced lower rectal cancer: comparison with the conventional transabdominal approach

BACKGROUND

An optimal surgical approach to lateral lymph node dissection (LLND) remains controversial. With the recent popularity of transanal total mesorectal excision, a two-team procedure combining the transabdominal and transanal approaches was established as a novel approach to LLND. This study aimed to clarify the safety and feasibility of two-team LLND (2team-LLND) and compare its short-term outcomes with those of conventional transabdominal LLND (Conv-LLND).

METHODS

Between April 2013 and March 2020, 463 patients diagnosed with primary locally advanced rectal cancer underwent a transanal total mesorectal excision; among them, 93 patients who underwent bilateral prophylactic LLND were included in this single-center, retrospective study. Among these patients, 50 and 43 patients underwent Conv-LLND (the Conv-LLND group) and 2team-LLND (the 2team-LLND group), respectively. The short-term outcomes, including the operation time, blood loss volume, number of complications, and number of harvested lymph nodes, were compared between the two groups.

RESULTS

The intraoperative and postoperative complications in the 2team-LLND group were equivalent to those in the Conv-LLND group; furthermore, the incidence of postoperative urinary retention in the 2team-LLND group was acceptably low (9%). Compared with the Conv-LLND group, the 2team-LLND group had a significantly shorter operation time (P = 0.003), lower median blood loss (P = 0.02), and higher number of harvested lateral lymph nodes (P = 0.0005).

CONCLUSION

The intraoperative and postoperative complications of 2team-LLND were comparable with those of Conv-LLND. Thus, 2team-LLND was safe and feasible for advanced lower rectal cancer. Moreover, it was superior to Conv-LLND in terms of the operation time, blood loss volume, and number of harvested lateral lymph nodes. Therefore, it can be a promising LLND approach.

Efficacy and Safety of Radical Resection of Rectal Cancer Combined with Selective Lateral Lymph Node Dissection in the Treatment of Low Rectal Cancer under Meta-analysis

Rectal cancer mostly occurs in the middle and low position in China, and many anatomical evidence has confirmed that Lateral Lymph Node Metastasis (LLNM) exists in middle and low rectal cancer. Laparoscopic surgery can penetrate into the pelvic cavity and magnify and narrow the visual field, which is helpful for lymph node dissection and vascular nerve protection, while it has minimally invasive characteristics and is considered to be more suitable for LLND. Relevant articles published from January 2000 to May 2022 are searched using "Rectal cancer, Lateral lymph node dissection, Radical resection of rectal cancer, Low rectal cancer, Laparoscopic therapy, Treatment of rectal cancer" as test terms, analyzed and assessed using Rev Man 5.3 software and Stata software to assess the risk bias of included references, and heterogeneity among each study is evaluated using Q test and heterogeneity (I2). The experimental results show that there is no heterogeneity among the studies (I2 = 8.46%). The heterogeneity of lymphatic metastasis in the included literature is evaluated, and the results show that there is heterogeneity between the studies (I2 = 52.06%).