Lymph node harvest in colon and rectal cancer: Current considerations

Does lymph node dissection improve the prognosis of patients with colorectal cancer?

The number of lymph nodes (LNs) dissected during surgery has become an interesting topic. Simple intuition always leads us to believe that dissecting more LNs will result in more accurate pathological staging and assurance of surgical quality. However, when the number of LNs dissected reaches a certain threshold, the patient's prognosis does not continue to improve as the number of dissected nodes increases. Instead, an increase in the number of dissected LNs may be accompanied by a higher incidence of complications. Currently, there are only less than 40% of colorectal cancer patients undergoing adequate LN evaluation. Therefore, obtaining a sufficient number of LNs in clinical practice is extremely challenging. How to further address the insufficiency of LN dissection due to various reasons, which results in concerns of surgeons about patient prognosis, is currently a critical focus.

Randomized clinical trial on accelerated preoperative hyperfractionated radiotherapy versus preoperative hyperfractionated radio-chemotherapy in locally advanced rectal cancer

OBJECTIVES

The aim of this study was to compare pathological response rates after preoperative hyperfractionated radiotherapy with co-administration of chemotherapy based on 5FU (HART-CT) versus preoperative hyperfractionated radiotherapy (HART) in patients with resectable rectal cancer.

METHODS

Patients with T2/N+ or T3/any N rectal cancer were randomized either to HART twice a day (28 fractions of 1.5 Gy) to total dose 42 Gy or to HART-CT. Tumour regression grade was postoperatively assessed according to the 4-point scale as recommended by the American Joint Committee on Cancer (AJCC). The secondary endpoints included overall survival (OS), disease-free survival (DFS), toxicity of preoperative treatment, locoregional, and distant failure rates. There were 187 patients eligible for analysis: 95 in HART and 92 in the HART-CT. Median follow-up was 5.6 years.

RESULTS

The analysis demonstrated a significantly higher chance of achieving pathologic complete response in HART-CT arm: complete response was achieved in 4/95, 4% (HART) and 11/92, 12% (HART-CT) (P = .045). The differences in OS and DFS, while tending to favour HART-CT, were not significant: OS (P = .13, hazard ratio [HR] = 0.82, 95% CI, 0.63-1.06) and DFS (P = .32; HR = 0.88, 95% CI, 0.69-1.13). The locoregional failure and distant metastases rates did not statistically differ between the trial arms. The rate of late complications was similar (P = .51), grade 3+ being 8% versus 11% in the HART/HART-CT group, respectively.

CONCLUSIONS

The hyperfractionated preoperative radiotherapy with concurrent 5-Fu-based chemotherapy (HART-CT) improved pathological response rate compared to HART. This translated into favourable OS and DFS in HART-CT, but the differences did not reach the threshold for significance.

ADVANCES IN KNOWLEDGE

A new hyperfractionated chemo-RT scheme is proposed. Histopathological major response (TRG 0-1) is associated with better clinical outcome.

Oncological and Clinical Impacts of Routine Splenic Flexure Mobilization in Anterior Resection

Background Splenic flexure mobilization (SFM) is widely regarded as one of the most challenging steps in laparoscopic and robotic colorectal surgery, sparking ongoing debate. Some surgeons routinely advocate for SFM, citing its role in achieving greater left colonic reach, which facilitates a safe, tension-free, and well-vascularized anastomosis while adhering to oncological principles. Conversely, others argue that SFM does not consistently ensure these benefits and may increase the risk of complications, including splenic, bowel, or vascular injuries, as well as unnecessarily prolonging the procedure. While traditional surgical textbooks consider SFM a mandatory step in open colorectal resections, limited evidence supports its necessity in minimally invasive approaches. Aim This study aims to evaluate whether routinely mobilizing the splenic flexure offers advantages from both oncological and clinical perspectives. Materials and methods This retrospective cohort study evaluated the oncological and clinical outcomes of SFM versus splenic flexure preservation (SFP) in anterior resections for malignant pathologies. The study was conducted at New Cross Hospital in Wolverhampton, United Kingdom, over a 24-month period, from March 2022 to March 2024. Anterior resections for benign pathologies were excluded. Data analysis was performed using IBM SPSS Statistics for Windows, Version 24.0 (Released 2016; IBM Corp., Armonk, NY, USA) and Microsoft Excel (Microsoft Corporation, Redmond, WA, USA). Results This study included 94 patients, with 65 undergoing SFM and 29 having it preserved (SFP). No significant differences in baseline demographics (age and gender) were observed between the groups. Oncological outcomes revealed a significantly longer median length of resected specimens in the SFM group, although lymph node counts and high vascular ties were comparable between the groups. There were no differences in R0 resection rates. Clinical outcomes showed similar hospital stays and operation durations in both groups. The SFM group had a slightly higher rate of stoma formation but a lower incidence of anastomotic leaks compared to the SFP group. No significant differences in splenic injuries or other complications were noted. Conclusions Our study suggests that routine SFM offers certain oncological and clinical benefits. The specimens obtained were more complete for pathological staging. The additional length gained from the maneuver not only results in longer specimens but also provides sufficient mobility of the remaining colon, enabling anastomosis with minimal tension, which helps prevent anastomotic leaks. Surgeons may consider adjusting their practices based on the findings of this study.

A Prognostic Model Based on the Log Odds Ratio of Positive Lymph Nodes Predicts Prognosis of Patients with Rectal Cancer

OBJECTIVE

This study aimed to compare the prognostic value of rectal cancer by comparing different lymph node staging systems, and a nomogram was constructed based on superior lymph node staging.

METHODS

Overall, 8700 patients with rectal cancer was obtained from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. The area under the curve (AUC), the C index, and the Akaike informativeness criteria (AIC) were used to examine the predict ability of various lymph node staging methods. Prognostic indicators were assessed using univariate and multivariate COX regression, and further correlation nomograms were created after the data were randomly split into training and validation cohorts. To evaluate the effectiveness of the model, the C index, calibration curves, decision curves (DCA), and receiver operating characteristic curve (ROC) were used. We ran Kaplan-Meier survival analyses to look for variations in risk classification.

RESULTS

While compared to the N-stage positive lymph node ratio (LNR), the log odds ratio of positive lymph nodes (LODDS) had the highest predictive effectiveness. Multifactorial COX regression analyses were used to create nomograms for overall survival (OS) and cancer-specific survival (CSS). The C indices of OS and CSS for this model were considerably higher than those for TNM staging in the training cohort. The created nomograms demonstrated good efficacy based on ROC, rectification, and decision curves. Kaplan-Meier survival analysis revealed notable variations in patient survival across various patient strata.

CONCLUSIONS

Compared to AJCC staging, the LODDS-based nomograms have a more accurate predictive effectiveness in predicting OS and CSS in patients with rectal cancer.

Lymph node dissection does not affect the survival of patients with tumor node metastasis stages I and II colorectal cancer

BACKGROUND

The effect of the number of lymph node dissections (LNDs) during radical resection for colorectal cancer (CRC) on overall survival (OS) remains controversial.

AIM

To investigate the association between the number of LNDs and OS in patients with tumor node metastasis (TNM) stage I-II CRC undergoing radical resection.

METHODS

Patients who underwent radical resection for CRC at a single-center hospital between January 2011 and December 2021 were retrospectively analyzed. Cox regression analyses were performed to identify the independent predictors of OS at different T stages.

RESULTS

A total of 2850 patients who underwent laparoscopic radical resection for CRC were enrolled. At stage T1, age [P < 0.01, hazard ratio (HR) = 1.075, 95% confidence interval (CI): 1.019-1.134] and tumour size (P = 0.021, HR = 3.635, 95%CI: 1.210-10.917) were independent risk factors for OS. At stage T2, age (P < 0.01, HR = 1.064, 95%CI: 1.032-1.098) and overall complications (P = 0.012, HR = 2.297, 95%CI: 1.200-4.397) were independent risk factors for OS. At stage T3, only age (P < 0.01, HR = 1.047, 95%CI: 1.027-1.066) was an independent risk factor for OS. At stage T4, age (P < 0.01, HR = 1.057, 95%CI: 1.039-1.075) and body mass index (P = 0. 034, HR = 0.941, 95%CI: 0.890-0.995) were independent risk factors for OS. However, there was no association between LNDs and OS in stages I and II.

CONCLUSION

The number of LDNs did not affect the survival of patients with TNM stages I and II CRC. Therefore, insufficient LNDs should not be a cause for alarm during the surgery.

Advanced Preoperative Clinical Stage Is Associated With More Lymph Node Harvest in Patients With Right Colon Cancer

PURPOSE

The adequacy of lymph node (LN) harvest is important in oncological colon cancer resections. While several studies have suggested factors influencing LN yield in colon cancer, limited data are available only regarding right hemicolectomies with complete mesocolic excision (CME) and central vessel ligation (CVL).

METHODS

A retrospective analysis was conducted on 169 patients who underwent right hemicolectomies with CME and CVL for right-sided colon cancer between February 2019 and March 2023. The patients were divided into 2 groups: groups with ≤24 LN yield and >24 LN yield, and the patient, surgical, and pathologic factors, which could potentially influence the LN yield, were analyzed.

RESULTS

Younger age, lower American Society of Anesthesiologists (ASA) classification, and advanced clinical TNM (cTNM) stage among patient factors, the presence of obstructions regarding the surgical factors, and the presence of desmoplastic tumor reaction in the pathologic factors were more likely to harvest >24 LNs. In a multivariate analysis, younger age, lower ASA classification, advanced cTNM stage, and an ileocolic artery (ICA) crossing pattern posterior to the superior mesenteric vein (SMV) were independently associated with a >24 LN harvest. Patients with cTNM 3,4 showed the tendency of > 24 LN yield consistently within each subgroup, irrespective of the age, ASA classification, and ileocolic artery crossing pattern.

CONCLUSIONS

Our investigation revealed a significant correlation between the advanced preoperative clinical stage and an increased number of harvested lymph nodes (LNs) in patients undergoing right hemicolectomies with CME a CVL. The observed association is potentially influenced by tumor aggressiveness and the extent of surgical resection performed by the surgeon. To elucidate the intricate relationship between surgical outcomes and the quantity of LN harvest in patients subjected to standardized CME and CVL for right-sided colon cancer, further dedicated research is warranted.

Management of Surgically Accessible Lymph Nodes Beyond Normal Resection Planes

This article discusses the management of isolated metastatic lymph nodes for colon and rectal cancer. There are traditionally significant differences in how certain regions of lymph nodes for colon and rectal cancer are managed in the East and West. This has led to the development of the lateral lymph node dissection for rectal cancer and extended lymphadenectomy techniques for colon cancer. This article will evaluate the literature on these techniques and what the surgical and oncological outcomes are at this time. In addition, colon and rectal cancers can occasionally have isolated distant lymph node metastases. These would traditionally be treated as systemic disease with chemotherapy. There is consideration though that these could be treated as similar to isolated liver or lung metastases which have been shown to be able to be treated surgically with good oncological results. The literature for these isolated distant lymph node metastases will be reviewed and treatment options available will be discussed.

Prognostic Value of Metastatic Lymph Node Ratio and Identification of Factors Influencing the Lymph Node Yield in Patients Undergoing Curative Colon Cancer Resection

Due to the impact of nodal metastasis on colon cancer prognosis, adequate regional lymph node resection and accurate pathological evaluation are required. The ratio of metastatic to examined nodes may bring an additional prognostic value to the actual staging system. This study analyzes the identification of factors influencing a high lymph node yield and its impact on survival. The lymph node ratio was determined in patients with fewer than 12 or at least 12 evaluated nodes. The study included patients after radical colon cancer resection in UICC stages II and III. For the lymph node ratio (LNR) analysis, node-positive patients were divided into four categories: i.e., LNR 1 (<0.05), LNR 2 (≥0.05; <0.2), LNR 3 (≥0.2; <0.4), and LNR 4 (≥0.4), and classified into two groups: i.e., those with <12 and ≥12 evaluated nodes. The study was conducted on 7012 patients who met the set criteria and were included in the data analysis. The mean number of examined lymph nodes was 22.08 (SD 10.64, median 20). Among the study subjects, 94.5% had 12 or more nodes evaluated. These patients were more likely to be younger, women, with a lower ASA classification, pT3 and pN2 categories. Also, they had no risk factors and frequently had a right-sided tumor. In the multivariate analysis, a younger age, ASA classification of II and III, high pT and pN categories, absence of risk factors, and right-sided location remained independent predictors for a lymph node yield ≥12. The univariate survival analysis of the entire cohort demonstrated a better five-year overall survival (OS) in patients with at least 12 lymph nodes examined (68% vs. 63%, p = 0.027). The LNR groups showed a significant association with OS, reaching from 75.5% for LNR 1 to 33.1% for LNR 4 (p < 0.001) in the ≥12 cohort, and from 74.8% for LNR2 to 49.3% for LNR4 (p = 0.007) in the <12 cohort. This influence remained significant and independent in multivariate analyses. The hazard ratios ranged from 1.016 to 2.698 for patients with less than 12 nodes, and from 1.248 to 3.615 for those with at least 12 nodes. The LNR allowed for a more precise estimation of the OS compared with the pN classification system. The metastatic lymph node ratio is an independent predictor for survival and should be included in current staging and therapeutic decision-making processes.

Does robotic TME bring difference in lymph node yield and quality of TME?

BACKGROUNDS

Oncological outcomes of the robotic low anterior rectal resection with total mesorectal excision (TME) are still under discussion. Few studies have proven that robotic TME (rTME) is a safe and equivalent method for treatment of rectal carcinoma. But there is almost no comparison between the rTME and conventional TME in terms of the number of lymph nodes obtained and the quality of the TME.

METHODS

A single institution retrospective study was designed in a cohort of 261 patients. Cohort was divided into two groups depending on the type of surgery (rTME versus TME) and within these two groups, patients were divided according to whether they underwent neoadjuvant chemoradiation (nCHRT) or did not. The primary objective of the study was to compare obtained number of the lymph nodes in specimen. Secondary objectives were comparison of the quality of the TME and the number of positive circumferential resection margins.

RESULTS

Results of the study have shown no significant difference in number of the lymph nodes obtained by the rTME and TME. There was no difference in the quality of the TME, neither in the group with the previous nCHRT nor in the group without a nCHRT.

CONCLUSION

With results from the study we consider the rTME to be non-inferior to the conventional TME. Therefore, at least identical oncological results can be expected in patients treated by the rTME.

The topographical distribution of lymph node metastases in colon cancer resections

In accordance with international guidelines all lymph nodes in colon cancer specimens must be examined to obtain accurate staging. This study aimed to determine the topographical location of lymph node metastases and evaluate if a more limited sampling approach could be an alternative. Partial colectomies received at the Department of Pathology, Zealand University Hospital during a six-month period were included. At the macroscopic examination, each specimen was divided into three different segments: a segment containing the index tumor and the tumor-feeding artery, an oral and an anal segment. The number of lymph nodes and lymph node metastases were registered separately for each segment. Resections from 93 patients were included. Of 2466 lymph nodes, 1839 (74.6 %) were located in the tumor segment, 308 (12.5 %) in the oral, and 319 (12.9 %) in the anal segment, respectively. In 133 (5,4 %) lymph nodes a metastasis was present. Of these 129 (97.0 %) were located in the tumor segment, one (0.8 %) in the oral segment, and three (2.3 %) in the anal segment. No patients had metastasis in the oral or anal segments without metastases also being present in the tumor segment leading to consideration of the need for lymph node harvest of the complete specimen upon initial examination. As such, the segment containing the index tumor and tumor-feeding artery could be regarded as a sentinel segment indicating a potential need for lymph node dissection in the oral and anal segments.

Impact of neoadjuvant chemotherapy for locally advanced colon cancer on postoperative complications

PURPOSE

Although not considered standard therapy, neoadjuvant chemotherapy (NAC) is an encouraging alternative for selected patients with locally advanced colon cancer (LAC). The aim of this study was to compare 30-day postoperative outcomes between patients undergoing upfront surgery and those undergoing NAC for LAC.

METHODS

Using the ACS-NSQIP data from 2016 to 2020, 11,498 patients with LAC were divided into those who underwent upfront colectomy (96.2%) and those who received NAC (3.8%). The primary outcome was a composite outcome encompassing 30-day major postoperative complications. Propensity score matched (PSM) analysis and multivariable logistic regression were performed.

RESULTS

After PSM analysis, there was no statistically significant difference in the development of a major complication. NAC was not significantly associated with the primary outcome. Risk factors for postoperative complications were T4 stage, older age, male sex, black race, smoking, dependent status, severe COPD, hypoalbuminemia, and preoperative transfusion. Laparoscopic and robotic surgery was protective.

CONCLUSION

NAC did not increase the odds of developing a major complication.

Predictors and survival outcomes of having less than 12 harvested lymph nodes in proctectomy for rectal cancer

BACKGROUND

Current recommendations suggest that a minimum of 12 lymph nodes (LNs) should be harvested during curative rectal cancer resection. We aimed to assess predictors and survival outcomes of harvesting < 12 lymph nodes in rectal cancer surgery.

METHODS

A retrospective case-control analysis of factors associated with harvesting < 12 LNs in rectal cancer surgery was conducted. Data were derived from the National Cancer Database 2010-2019. Univariate and multivariate binary logistic regression analyses were performed to determine predictors of harvesting < 12 LNs. Association between harvesting < 12 LNs and 5-year overall survival (OS) was assessed using Cox regression and Kaplan Meier statistics.

RESULTS

67,529 patients (60.8% male; mean age: 61.2 ± 12.5 years) were included. Median number of harvested LNs was 15 (IQR: 11-20); 27.1% of patients had < 12 harvested LNs. Independent predictors of harvesting < 12 LNs were older age (OR: 1.016;p < 0.001), neoadjuvant systemic treatment (OR: 1.522;p < 0.001), neoadjuvant radiation treatment (OR: 1.367;p < 0.001), longer duration of radiation therapy (OR: 1.003;p < 0.001) and abdominoperineal resection (OR: 1.071;p = 0.017). Higher clinical TNM stage and tumor grade, pull-through coloanal anastomosis, and minimally invasive surgery were independently associated with ≥ 12 harvested LNs. < 12 harvested LNs was independently associated with lower 5-year OS (HR: 1.24;p < 0.001) and shorter mean OS (96.7 vs 102.8 months;p < 0.001) than ≥ 12 harvested LNs.

CONCLUSIONS

Older age, open resection, and neoadjuvant therapy were independent predictors of < 12 harvested LNs. Conversely, higher clinical TNM stage and tumor grade, coloanal anastomosis, and minimally invasive surgery were predictive of ≥ 12 harvested LNs. < 12 LNs harvested was associated with lower OS.

Lymph node yield in colorectal cancer specimens and its impact on pathological staging: Does number matter?

Introduction

Regional lymph node involvement is an important predictor of outcome in colorectal cancer (CRC). The lymph node yield in resected specimens varies from case to case.

Aim

To assess whether clinicopathologic factors have an impact on the number of lymph nodes harvested from surgical resection specimens of CRCs To assess whether the total number of lymph nodes retrieved has a bearing on the positivity of lymph nodes and hence the N category.

Materials and Methods

All resection specimens of treatment naïve CRC received in the department of pathology during a 2 year period (2017-2019) were reviewed. The lymph node yield was correlated with age, sex, type of surgical procedure, length of resected segment, tumor location, histological type and grade, T and N categories. The statistical tests used were Spearman rank, Mann-Whitney U, Kruskal-Wallis, and Chi-square tests.

Results

A total of 51 resections were studied. The mean age was 59.64 years with 72.55% being male. About 76.47% were hemicolectomies and 23.52% were rectosigmoid surgeries. The lymph node yield ranged from 0 to 38, the mean being 12.67. None of the parameters studied had a significant correlation with the lymph node yield except histological grade, specimens with higher-grade tumors yielding more number of nodes (P = 0.0242). There was no significant correlation between node positivity and the average number of lymph nodes (P = 0.0883). There was no significant correlation between total yield in cases with ≥12 lymph nodes and N category (P = 0.180). Furthermore, there was no significant correlation between total yield in node-positive cases with ≥12 lymph nodes and N category (P = 0.216). There was no significant difference in the sizes of the lymph nodes in node-positive and negative cases (P = 0.3930 and 0.2355, respectively).

Conclusion

Among the parameters affecting lymph node yield, the current study found a significant correlation between histological grade and lymph node yield. There was no significant difference in the size of lymph nodes between node-positive and negative cases. The total lymph node yield did not have a bearing on node positivity and this shows that a lower lymph node yield may be accepted as adequate after thorough examination of the specimen.

A systematic review and meta-analysis of the use of methylene blue to improve the lymph node harvest in rectal cancer surgery

BACKGROUND

Methylene blue staining of the resected specimen has been described as an alternative to the conventional palpation and visual inspection method to improve lymph node harvest. This meta-analysis evaluates the usefulness of this technique in surgery for rectal cancer, particularly after neoadjuvant therapy.

METHODS

Randomized controlled trials (RCTs) comparing lymph node harvest in methylene blue-stained rectal specimens to those of unstained specimens were identified from the Medline, Embase, and Cochrane databases. Non-randomized studies and those with only colonic resections were excluded. The quality of RCTs was assessed using Cochrane's risk of bias tool. A weighted mean difference (WMD) was calculated for overall harvest, harvest after neoadjuvant therapy, and metastatic nodal yield. In contrast, the risk difference (RD) was calculated to compare yields of less than 12 lymph nodes between the stained and unstained specimens.

RESULTS

Study selection comprised seven RCTs with 343 patients in the unstained group and 337 in the stained group. Overall lymph node harvest and harvest after neoadjuvant therapy were significantly higher in stained specimens with a WMD of 13.4 and 10.6 and a 95% confidence interval (CI) of 9.5-17.2 and 4.8-16.3, respectively. Harvest of metastatic lymph nodes was significantly higher in the stained group (WMD 1.0, 95% CI 0.6-1.4). The yield of less than 12 lymph nodes was significantly higher in the unstained group with RD of 0.292 and 95% CI of 0.182-0.403.

CONCLUSION

Despite a small number of patients, this meta-analysis confirms improved lymph node harvest in surgical specimens stained with methylene blue compared with unstained specimens.

Evaluation of lymph node adequacy in patients with colorectal cancer: Results from a referral center in Iran

Background

The presence of lymph node metastasis is one of the most important prognostic factors for long-term survival of patients with colorectal cancer. Therefore, thorough pathologic examination of at least 12 lymph nodes is essential for accurate staging of this disease, as well as for choosing the best adjuvant treatment. The aim of this study is to assess the adequacy of lymph node harvest in patients with colorectal cancer.

Methods

This observational, cross-sectional study was performed on 584 patients with colorectal adenocarcinoma who had undergone surgery from 2012 to 2017. Thereafter, the relevant demographic, pathological, and surgical data were extracted from the patients' medical records; and a relationship between the number of evaluated lymph nodes and other variables was also assessed.

Results

Among 584 studies cases in this study, 336 (57.5%) subjects had fewer than 12 evaluated lymph nodes. Mean and median number of the evaluated lymph nodes were calculated as 10.7 (±5.6) and 10, respectively. The patients aged 60 years old and older and the cases with tumors located in descending colon and rectum were observed to have a higher likelihood of inadequate lymph node retrieval. After an average follow-up of a 60-month period, 63% of the patients were alive. For the patients in whom fewer than 12 lymph nodes had been assessed, the median survival was estimated to be 48 months. For the patients in whom the number of evaluated lymph nodes was ≥12, median survival was calculated to be 54 months.

Conclusion

The number of lymph nodes evaluated in our study was less than the standard number in more than half of the patients. Among various other factors, older age and tumor location in descending colon and rectum are found to be associated with suboptimal assessment of lymph nodes. The number of lymph nodes dissected is also associated with survival.

Laparoscopic right colectomies with intracorporeal compared to extracorporeal anastomotic techniques are associated with reduced post-operative incisional hernias

Background

Owing to important differences in surgical technique, laparoscopic right colectomy with intracorporeal (ICA) compared to extracorporeal (ECA) anastomotic technique may result in improved patient outcomes. We aimed to compare both techniques according to incisional hernias and other pertinent perioperative characteristics, post-operative complications, and oncologic quality markers.

Methods

All adult patients undergoing laparoscopic right colectomies between 2015 and 2020 at a single institution were included. ICA and ECA techniques were compared based on selected outcomes using univariable and multivariable statistical analyses, as appropriate. Subgroup analyses were restricted to patients with neoplastic indications for surgery and non-urgent operations.

Results

A total of 517 patients met inclusion criteria, of which 139 (26.9%) underwent ICA and 378 (73.1%) underwent ECA. ICA and ECA patients had similar baseline characteristics. At two years of follow-up, a lower proportion of ICA patients developed a hernia at the extraction incision (1.5% vs. 7.1%, p = 0.02) and ICA was associated with an 80% reduction in extraction incision hernias (aHR 0.20, p = 0.03). These results were stable through subgroup and sensitivity analyses. Median operative time was longer in the ICA group (186 min vs. 135 min, p < 0.001), but the gap in operative time narrowed during the study period. Median length of stay was one calendar day shorter in the ICA group (3 days vs. 4 days, p = 0.007) and ICA was associated with a 13% decrease in the length of stay (aRR 0.87, p = 0.02). The incidence of superficial wound infections, anastomotic leaks and re-interventions was lower in ICA patients, but this difference was not statistically significant. 90-day unscheduled visits, readmissions, and mortalities were similar across both groups, as were oncologic outcomes.

Conclusion

Laparoscopic right colectomies with intracorporeal anastomoses are associated with a reduction in incisional hernias and shorter hospital lengths of stay without compromising on patient safety or oncologic principles.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-022-09585-0.

Lymph node regression grading of locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

Neoadjuvant chemoradiotherapy (nCRT) and total rectal mesenteric excision are the main standards of treatment for locally advanced rectal cancer (LARC). Lymph node regression grade (LRG) is an indicator of prognosis and response to preoperative nCRT based on postsurgical metastatic lymph node pathology. Common histopathological findings in metastatic lymph nodes after nCRT include necrosis, hemorrhage, nodular fibrosis, foamy histiocytes, cystic cell reactions, areas of hyalinosis, residual cancer cells, and pools of mucin. A number of LRG systems designed to classify the amount of lymph node regression after nCRT is mainly concerned with the relationship between residual cancer cells and regressive fibrosis and with estimating the number of lymph nodes existing with residual cancer cells. LRG offers significant prognostic information, and in most cases, LRG after nCRT correlates with patient outcomes. In this review, we describe the systematic classification of LRG after nCRT, patient prognosis, the correlation with tumor regression grade, and the typical histopathological findings of lymph nodes. This work may serve as a reference to help predict the clinical complete response and determine lymph node regression in patients based on preservation strategies, allowing for the formulation of more accurate treatment strategies for LARC patients, which has important clinical significance and scientific value.

Is a cutoff value of 12 still useful in stage II right-sided colon cancer without risk factors?

Purpose

Various clinical practice guidelines recommend at least 12 regional lymph nodes should be removed for resected colon cancer. According to a recent study, the lymph node yield (LNY) in colon cancer surgery in the last 20 years has tended to increase from 14.91 to 21.30. However, it is unclear whether these guidelines adequately reflect recent findings on the number of harvested lymph nodes in colon cancer surgery. The aim of this study is to assess the impact of an LNY of more than 25 on survival in right-sided colon cancer.

Methods

We included 285 patients who underwent a right hemicolectomy during the period from January 2010 through December 2015. Patients were divided into two groups (<25 nodes and ≥25 nodes). Primary endpoints included 5-year and 10-year survival including disease-free and overall.

Results

We found that survival outcomes of patients with a harvest of ≥25 nodes were not significantly different compared with a <25 group. Large tumor size (5 cm) is significantly associated with poor 5-year and 10-year overall survival.

Conclusion

Survival outcomes of patients with a harvest of ≥25 nodes were not significantly different compared with the <25 group in stage II colon cancer with no risk.

Validated Risk-Score Model Predicting Lymph Node Metastases in Patients with Non-Functional Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

The incidence of, and factors associated with, lymph node metastasis (LN+) in non-functional gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are not well characterized.

METHODS

Patients were identified from the 2010-2015 National Cancer Database who underwent surgical resection with lymphadenectomy for clinical stage I-III non-functional GEP NETs. Among a randomly selected training subset of 75% of the study population, variables associated with LN+ were identified using multivariable logistic regression analysis, and these variables were used to create a risk-score model for LN+, which was internally validated among the remaining 25% of the cohort.

RESULTS

Of 12,228 patients evaluated, 6,902 (56.4%) had LN+. Among the training set, variables associated with LN+ included age (70 years of age or older: odds ratio [OR] 1.12, 95% CI 1.00-1.24; ref: less than 70 years), tumor location (stomach: OR 3.72, 95% CI 2.94-4.71; small intestine: OR 19.60, 95% CI 17.31-22.19; ref: pancreas), tumor grade (moderately differentiated: OR 1.47, 95% CI 1.30-1.67; poorly differentiated/anaplastic: OR 1.53, 95% CI 1.21-1.95; ref: well-differentiated), tumor size (2-4 cm: OR 2.40, 95% CI 2.13-2.70; >4 cm: OR 5.25, 95% CI 4.47-6.17; ref: <2 cm), and lymphovascular invasion (OR 5.62, 95% CI 5.08-6.21; ref: no lymphovascular invasion). After internal validation, a risk-score model for LN+ using these variables was developed composed of low- (N = 2,779), intermediate- (N = 2,598), high- (N = 3,433), and very-high-risk (N = 3,418) groups; within each group the rate of LN+ was 8.7%, 48.6%, 64.9%, and 92.8%, respectively.

CONCLUSIONS

This developed risk-score model, including both patient and tumor variables, can be used to calculate the risk for LN metastases in patients with GEP NETs.

Long-term Outcomes of Minimally Invasive Versus Open Abdominoperineal Resection for Rectal Cancer: A Single Specialized Center Experience

BACKGROUND

Randomized studies have validated laparoscopic proctectomy for the treatment of rectal cancer as noninferior to an open proctectomy, but most of those studies have included sphincter-preserving resections along with abdominoperineal resection.

OBJECTIVE

This study aimed to compare perioperative and long-term oncological outcomes between minimally invasive and open abdominoperineal resection.

DESIGN

This study is a retrospective analysis of a prospectively maintained database.

SETTINGS

The study was conducted in a single specialized colorectal surgery department.

PATIENTS

All patients who underwent abdominoperineal resection for primary rectal cancer between 2000 and 2016 were included.

MAIN OUTCOME MEASURES

The primary outcomes measured were the perioperative and long-term oncological outcomes.

RESULTS

We included 452 patients, 372 in the open group and 80 in the minimally invasive group, with a median follow-up time of 74 months. There were significant differences between the groups in terms of neoadjuvant radiation treatment (67.5% of the open versus 81.3% of the minimally invasive group, p = 0.01), operative time (mean of 200 minutes versus 287 minutes, p < 0.0001), and mean length of stay (9.5 days versus 6.6 days, p < 0.0001). Overall complication rates were similar between the groups (34.5% versus 27.5%, p = 0.177). There were no significant differences in the mean number of lymph nodes harvested (21.7 versus 22.2 nodes, p = 0.7), circumferential radial margins (1.48 cm versus 1.37 cm, p = 0.4), or in the rate of involved radial margins (10.8% versus 6.3%, p = 0.37). Five-year overall survival was 70% in the open group versus 80% in the minimally invasive group (p = 0.344), whereas the 5-year disease-free survival rate in the open group was 63.2% versus 77.6% in the minimally invasive group (p = 0.09).

LIMITATIONS

This study was limited because it describes a single referral institution experience.

CONCLUSIONS

Although both approaches have similar perioperative outcomes, the minimally invasive approach benefits the patients with a shorter length of stay and a lower risk for surgical wound infections. Both approaches yield similar oncological technical quality in terms of the lymph nodes harvested and margins status, and they have comparable long-term oncological outcomes. See Video Abstract at http://links.lww.com/DCR/B754.RESULTADOS A LARGO PLAZO DE LA RESECCIÓN ABDOMINOPERINEAL MÍNIMAMENTE INVASIVA VERSUS ABIERTA PARA EL CÁNCER DE RECTO: EXPERIENCIA DE UN SOLO CENTRO ESPECIALIZADOANTECEDENTES:Estudios aleatorizados han validado la proctectomía laparoscópica para el tratamiento del cáncer de recto igual a la proctectomía abierta, pero la mayoría de esos estudios han incluido resecciones con preservación del esfínter junto con resección abdominoperineal.OBJETIVO:Comparar los resultados oncológicos perioperatorios y a largo plazo entre la resección abdominoperineal abierta y mínimamente invasiva.DISEÑO:Análisis retrospectivo de una base de datos mantenida de forma prospectiva.ENTORNO CLINICO:Servicio único especializado en cirugía colorrectal.PACIENTES:Todos los pacientes que se sometieron a resección abdominoperineal por cáncer de recto primario entre 2000 y 2016.PRINCIPALES MEDIDAS DE VALORACION:Resultados oncológicos perioperatorios y a largo plazo.RESULTADOS:Se incluyeron 452 pacientes, 372 en el grupo abierto y 80 en el grupo mínimamente invasivo, con una mediana de seguimiento de 74 meses. Hubo diferencias significativas entre los grupos en términos de tratamiento con radiación neoadyuvante (67,5% del grupo abierto versus 81,3% del grupo mínimamente invasivo, p = 0,01), tiempo operatorio (media de 200 minutos versus 287 minutos, p < 0,0001) y la duración media de la estancia (9,5 días frente a 6,6 días, p < 0,0001). Las tasas generales de complicaciones fueron similares entre los grupos (34,5% versus 27,5%, p = 0,177). No hubo diferencias significativas en el número medio de ganglios linfáticos extraídos (21,7 versus 22,2 ganglios, p = 0,7), márgenes radiales circunferenciales (1,48 cm y 1,37 cm, p = 0,4), ni en la tasa de márgenes radiales afectados (10,8 cm). % versus 6,3%, p = 0,37). La supervivencia general a 5 años fue del 70% en el grupo abierto frente al 80% en el grupo mínimamente invasivo (p = 0,344), mientras que la tasa de supervivencia libre de enfermedad a 5 años en el grupo abierto fue del 63,2% frente al 77,6% en el grupo mínimamente invasivo (p = 0,09).LIMITACIONES:Experiencia en una institución de referencia única.CONCLUSIONES:Si bien ambos tienen resultados perioperatorios similares, el enfoque mínimamente invasivo, beneficia a los pacientes con estadía más corta y menor riesgo de infecciones de la herida quirúrgica. Ambos enfoques, producen una calidad técnica oncológica similar en términos de ganglios linfáticos extraídos y estado de los márgenes, y tienen resultados oncológicos comparables a largo plazo. Consulte Video Resumen en http://links.lww.com/DCR/B754. (Traducción - Dr. Fidel Ruiz Healy).

Clinicopathological Factors Affecting Lymph Node Yield and Positivity in Left-Sided Colon and Rectal Cancers

Background

Colorectal cancer (CRC) is a significant cause of cancer‐related deaths worldwide and is the third most common cause of cancer deaths in the UK. The status of lymph node metastasis is a key factor for predicting the prognosis of a patient's CRC.

Aims

This study aimed to analyze the demographics of left-sided colonic and rectal cancers at a single institution. We looked closely at the correlation between patient age and various histological factors. We tried to find any significant difference in lymph node yield (LNY) between laparoscopic surgery (LS) and open surgery (OS). We aimed to identify any statistical correlation between LNY and lymph node positivity (LNP) with other patient, surgical and histopathological features.

Methodology

This is a retrospective, non-interventional review of consecutive patients who underwent left-sided colonic and rectal cancer resections over a three-year period between 01 April 2018 and 31 March 2021. Descriptive and inferential statistical analyses were used. Chi-squared / Fisher exact test was used on a categorical scale between two or more groups and non-parametric setting for qualitative data analysis.

Results

A total of 102 patients were included in the study. No statistical correlation was found between the age of the patient with the LNY, LNP, location of the tumor, type, and urgency of the operation. LNY ranged between one and 43 nodes (median (interquartile range (IQR)) 17, 8). There was no statistically significant difference in LNY between laparoscopic surgery (LS) and open surgery (OS) (p=0.1449). Significant statistical correlation was identified between LNP and completeness of resection (CoR) (p=0.039), vascular invasion (VI) (p<0.001), perineural invasion (PI) (p<0.001), and circumferential resectional margin involvement (CRMI) (p=0.039).

Discussion

LNY and LNP are important prognostic indices in colorectal cancer. Patient age, tumor location, the urgency of surgery, and consultant experience did not significantly impact the LNY. Our study showed a positive correlation between LNP and CRMI, VI and PI comparable to literature. Contrary to other studies, we found no statistical significance between LS vs. OS and LNY. Whether 12 nodes per patient is an appropriate level remains controversial.

Prognostic implications of ENE and LODDS in relation to lymph node-positive colorectal cancer location

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This is the first study on LODDS and ENE together. The current study showed that LODDS and ENE are liable prognostic parameters of CRC or CC.

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ENE is an independent influencing factor on the prognosis of both CRC and CC, and the prognostic impact of ENE was observed in both CRC and CC.

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The frequency of ENE increases from the proximal (right) to the distal (left) colon as well as the rectum.

Background

Extranodal extension (ENE) and log odds of positive lymph nodes (LODDS) are associated with the aggressiveness of both colon and rectal cancers. The current study evaluated the clinicopathological significance and the prognostic impact of ENE and LODDS in the colon and rectal patients independently.

Methods

The clinical and histological records of 389 colorectal cancer (CRC) patients who underwent curative surgery were reviewed.

Results

For the ENE system, 244 patients were in the ENE1 group and 145 in the ENE2 system. Compared with the ENE1 system, the patients included in the ENE2 system were prone to nerve invasion (P < 0.001) and vessel invasion (P < 0.001) with higher TNM (P = 0.009), higher T category (P = 0.003), higher N category (P < 0.001), advanced differentiation (P = 0.013), more number of positive lymph nodes (NPLN) (P < 0.001), more lymph node ratio (LNR) (P < 0.001), and a higher value of LODDS (P < 0.001). ENE was more frequent in patients with left and rectal than right cancer. For the LODDS system, 280 patients were in the LODDS1 group, and 109 in the LODDS2 group. Compared to the LODDS1 group, the patients included in the LODDS2 group were more prone to nerve invasion (P = 0.0351) and vessel invasion (P < 0.001) with a higher rate of N2 stage, less NDLN (P < 0.001), more NPLN (P < 0.001), more LNR (P < 0.001), and a higher value of ENE (P < 0.001). Based on the results in the univariable analysis, the N, NPLN, LNR, LODDS, and ENE were separately incorporated into five different Cox regression models combined with the same confounders. The multivariable Cox regression analysis demonstrated that all the five staging systems were independent prognostic factors for overall survival.

Conclusion

The current study confirmed that the LODDS stage is an independent influence on the prognosis of both CRC and CC patients. ENE is an independent influencing factor on the prognosis of both CRC and CC patients, and the prognostic impact of extracapsular lymph node was observed in both CRC and CC. The frequency of ENE increases from the proximal (right) to the distal (left) colon as well as the rectum. Therefore, combining ENE and LODDS into the current TNM system to compensate for the inadequacy of pN staging needs further investigation.

Outcomes of level of ligation of inferior mesenteric artery in colorectal cancer: a systematic review and meta-analysis

The level of ligation of the inferior mesenteric artery (IMA) is a critical factor that can influence outcomes. The aim of this meta-analysis was to compare outcomes following high or low ligation of IMA. A systematic search was performed for relevant articles published between 2000 and 2020. Meta-analysis was performed using fixed-effects or random-effects models; 31 studies were included. Results show significantly lower rates of anastomotic leak, postoperative morbidity and urinary dysfunction with low ligation compared with high ligation. Though recurrence rates were similar, 5-year overall survival was longer in the low ligation group. Low ligation of IMA decreases anastomotic leak rates and overall morbidity. Addition of IMA nodal clearance to low ligation appears to improve overall survival in colorectal cancer.

Real-world comparison of curative open, laparoscopic and robotic resections for sigmoid and rectal cancer-single center experience

There has been an increase in the utilization of robotic surgery in addition to traditional open or laparoscopic approaches. Aim of this study is to compare the short-term outcomes for open, laparoscopic, and robotic surgery for rectal and sigmoid cancer. One hundred and forty-seven patients (open n = 48, laparoscopic n = 49, robotic n = 50) undergoing curative resections by two surgeons between 2013 and 2020 were included. Data analyzed included patient demographics, tumor characteristics, length of stay, post-operative outcomes, and pathologic surrogates of oncologic results, including total mesorectal excision (TME) quality, circumferential resection margin (CRM) involvement and lymph node (LN) yield. Median age of population was 68 years (IQR 59-73), majority (68%) were males. Median distance from anal verge in the robotic surgery group was 8 cm, compared to 15 and 14.5 cm in the open and laparoscopic groups, respectively, p = 0.029, (laparoscopic vs robotic, p = 0.005 and open vs robotic, p = 0.027). Proportion of patients who received neoadjuvant radiotherapy in robotic surgery group was higher, p = 0.04. In sub-group of tumors between 3 and 7 cm from anal verge more patients in the robotic surgery group had sphincter preservation, p = 0.006. Length of stay, maximum C-reactive protein, and white blood cell rise favored minimally invasive approaches compared to open surgery. There were no differences in post-operative complications, lymph node yield or CRM positivity rate between the three groups. Robotic surgery approach is safe and allows sphincter preservation without compromising TME quality in rectal cancer surgery.

Effect of rurality and socioeconomic deprivation on presentation stage and long-term outcomes in patients undergoing surgery for colorectal cancer

BACKGROUND

Geographical remoteness and socioeconomic status (SES) are important factors affecting presentation stage and survival for colorectal cancer. A series of patients from a single institution in northern New South Wales was studied to determine if rural isolation or SES affected presentation and survival in patients undergoing resection.

METHODS

Consecutive colorectal cancer resections performed at Lismore Base Hospital from 2011 to 2019 were identified. Patient residential addresses were categorized by the Modified Monash Model (MMM), an Australian Government definition of rural isolation, and Socioeconomic Index for Areas (SEIFA) quintiles, an Australian Bureau of Statistics index of socioeconomic deprivation. Univariate and Cox regression survival analysis was performed on data from histopathology and clinical notes matched with survival data.

RESULTS

A total of 405 patients were included in MMM categories 3 (n = 207, 51.1%), 4 (n = 69, 17%) and 5 (n = 129, 31.9) corresponding to large, medium and small rural towns. MMM 3 was associated with emergency cases (25.6% versus 18.7%, P < 0.001), nodal disease (44.4% versus 38.4%, P = 0.018) and T3/4 tumours (82.1% versus 73.7%, P < 0.001) compared with isolated patients without difference in 5-year survival (P = 0.370). Disadvantaged SEIFA quintiles 1/2 demonstrated increased poor differentiation (23.0% versus 15.4%, P < 0.001) and vascular invasion (15.8% versus 9.1%, P < 0.001) with reduced 5-year survival (57.0% versus 70.4%, P = 0.039). Independent predictors of survival included age, emergency cases, group stage, lymphatic invasion and low lymph node yield.

CONCLUSION

A 'rural reversal' may be present for patients in northern New South Wales; however, SES and established clinicopathological factors are the strongest predictors of survival in our population.

Small Molecules for Multi-Wavelength Near-Infrared Fluorescent Mapping of Regional and Sentinel Lymph Nodes in Colorectal Cancer Staging

Assessing lymph node (LN) status during tumor resection is fundamental for the staging of colorectal cancer. Current guidelines require a minimum of 12 LNs to be harvested during resection and ultra-staging regional lymph nodes by sentinel lymph node (SLN) assessment is being extensively investigated. The current study presents novel near-infrared (NIR) fluorescent dyes for simultaneous pan lymph node (PanLN; regional) and SLN mapping. PanLN-Forte was intravenously injected in mice and assessed for accumulation in regional LNs. SLN800 was injected intradermally in mice, after which the collection and retention of fluorescence in SLNs were measured using indocyanine green (ICG) and its precursor, SLN700, as references. LNs in the cervical, inguinal, jejunal, iliac, and thoracic basins could clearly be distinguished after a low dose intravenous injection of PanLN-Forte. Background fluorescence was significantly lower compared to the parent compound ZW800-3A (p < 0.001). SLN700 and SLN800 specifically targeted SLNs with fluorescence being retained over 40-fold longer than the current clinically used agent ICG. Using SLN700 and SLN800, absolute fluorescence in SLN was at least 10 times higher than ICG in second-tier nodes, even at 1 hour post-injection. Histologically, the fluorescent signal localized in the LN medulla (PanLN-Forte) or sinus entry (SLN700/SLN800). PanLN-Forte and SLN800 appear to be optimal for real-time NIR fluorescence imaging of regional and SLNs, respectively.

Using the Fat-Clearing Technique to Improve Lymph Node Retrieval in Colorectal Cancer

College of American Pathologists recommended that at least 12 lymph nodes should be harvested for adequate staging of colorectal carcinoma. Lymph node harvesting is routinely performed by a manual technique of inspection and palpation, which is laborious and time-consuming. The study assessed the influence of the improved fat-clearing technique on the number of lymph nodes retrieved from colorectal cancer specimens and the clinical efficacy. Seventy colorectal cancer resection specimens were examined and assessed by 4 pathology residents. Thirty-five specimens were handled with the conventional manual technique by inspection and palpation, and the other 35 specimens with the improved fat-clearing technique to retrieve lymph nodes. As a result, compared with the conventional manual technique, the numbers of lymph nodes retrieved with the improved fat-clearing technique were significantly increased from 14.7 ± 6.2 lymph nodes to 20.8 ± 9.0 lymph nodes per specimen (P < .05). Besides, the percentage of cases with at least 12 lymph nodes retrieved increased from 80% to 91%. The result of this study pointed out that using the improved fat-clearing technique to process colorectal specimens could increase the lymph node yield effectively, and was effective, practical, and suitable for routine gross examination.

Adequacy of lymph node harvest following colectomy for obstructed and nonobstructed colon cancer

BACKGROUND

Technical and clinical differences in resection of obstructed and non-obstructed colon cancers may result in differences in lymph node retrieval. The objective of this study is to compare the lymph node harvest following resection of obstructed and nonobstructed colon cancer patients.

METHODS

A retrospective analysis utilizing the 2014-2018 NSQIP colectomy targeted data set was conducted. One-to-one coarsened exact matching (CEM) was utilized between patients undergoing resection for obstructed and non-obstructed colon cancer. The primary outcome was the adequacy of lymph node retrieval (LNR, ≥12 nodes).

RESULTS

CEM resulted in 9412 patients. Patients with obstructed tumors were more likely to have inadequate LNR (13.3% vs 8.2%, p < .001) compared to those with nonobstructed tumors. Multivariate analysis demonstrated that patients with obstructing tumors had worse LNR compared to non-obstructed tumors (odds ratio [OR]: 0.74, 95% confidence interval [CI]: 0.62-0.87; p < .005). Increased age (OR: 0.99, 95% CI: 0.098-0.99), presence of preoperative sepsis (OR: 0.70, 95% CI: 0.055-0.90), left-sided and sigmoid tumors compared to right-sided (OR: 0.64, 95% CI: 0.51-0.81; OR: 0.69, 95% CI: 0.58-0.82, respectively), and open surgical resection compared to an minimally invasive surgical approach were associated with inadequate LNR (p < .05).

CONCLUSION

This study demonstrated that resection for obstructing colon cancer compared to non-obstructed colon cancer is associated with increased odds of inadequate lymph node harvest.

The quality of lymph node harvests in extralevator abdominoperineal excisions

Background

Lymph node (LN) harvest in colorectal cancer resections is a well-recognised prognostic factor for disease staging and determining survival, particularly for node-negative (N0) diseases. Extralevator abdominoperineal excisions (ELAPE) aim to prevent “waisting” that occurs during conventional abdominoperineal resections (APR) for low rectal cancers, and reducing circumferential resection margin (CRM) infiltration rate. Our study investigates whether ELAPE may also improve the quality of LN harvests, addressing gaps in the literature.

Methods

This retrospective observational study reviewed 2 sets of 30 consecutive APRs before and after the adoption of ELAPE in our unit. The primary outcomes are the total LN counts and rates of meeting the standard of 12-minimum, particularly for those with node-negative disease. The secondary outcomes are the CRM involvement rates. Baseline characteristics including age, sex, laparoscopic or open surgery and the use of neoadjuvant chemoradiotherapy were accounted for in our analyses.

Results

Median LN counts were slightly higher in the ELAPE group (16.5 vs. 15). Specimens failing the minimum 12-LN requirements were almost significantly fewer in the ELAPE group (OR 0.456, P = 0.085). Among node-negative rectal cancers, significantly fewer resections failed the 12-LN standard in the ELAPE group than APR group (OR 0.211, P = 0.044). ELAPE led to a near-significant decrease in CRM involvement (OR 0.365, P = 0.088). These improvements were persistently observed after taking into account baselines and potential confounders in regression analyses.

Conclusion

ELAPE provides higher quality of LN harvests that meet the 12-minimal requirements than conventional APR, particularly in node-negative rectal cancers. The superiority is independent of potential confounding factors, and may implicate better clinical outcomes.