Optimizing lymph node harvest in laparoscopic colorectal cancer: predictors and station-specific lymph node submission solutions

Chun Gao; Sheng Zhang

doi:10.3393/ac.2025.01123.0160

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Original Article Colorectal cancer Optimizing lymph node harvest in laparoscopic colorectal cancer: predictors and station-specific lymph node submission solutions: Chun Gao, Sheng Zhang; Annals of Coloproctology 2026;42(2):216-225.
DOI: https://doi.org/10.3393/ac.2025.01123.0160
Published online: April 27, 2026

Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China

Correpsondence to: Sheng Zhang, MD Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jie Fang Ave 1095, Wuhan 430022, China Email: aloof3737@126.com

• Received: September 19, 2025 • Revised: October 14, 2025 • Accepted: November 4, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Abstract
INTRODUCTION
METHODS
RESULTS
DISCUSSION
ARTICLE INFORMATION
REFERENCES

Abstract

Purpose
Adequate lymph node yield is crucial for accurate staging in colorectal cancer. This study aims to analyze clinical factors associated with lymph node retrieval in laparoscopic colorectal cancer surgery and to explore strategies that may enhance yield.
Methods
We conducted a retrospective review of clinical, pathological, and surgical data from patients who underwent laparoscopic colorectal cancer resection between July 2019 and July 2024 at our institution. Patients were stratified by lymph node yield into 2 groups: <12 nodes (reduced yield) and ≥12 nodes (control). Univariate analyses were used to identify factors potentially affecting lymph node yield, and multivariate logistic regression was performed to determine independent risk factors for reduced yield.
Results
A total of 639 patients (305 with rectal cancer and 334 with colon cancer) were included. Univariate analysis identified age (P=0.039), sex (P=0.029), neoadjuvant therapy (P<0.001), tumor location (P<0.001), invasion depth (P<0.001), lymphovascular invasion (P=0.028), and station-specific lymph node submission (P<0.001) as influential factors. Multivariate analysis revealed that preoperative neoadjuvant therapy, tumor location (non–right colon), shallow invasion depth (T1–T2), and lack of station-specific submission independently contributed to reduced lymph node yield (all P<0.05).
Conclusion
This study highlights preoperative neoadjuvant therapy, tumor location, and invasion depth (T stage) as independent factors associated with reduced lymph node yield in laparoscopic colorectal cancer surgery. However, station-specific lymph node submission significantly increases yield and may help address inadequate retrieval. These findings suggest both predictive and interventional strategies to optimize lymph node harvest after surgery.
Keywords: Colorectal neoplasms; Laparoscopy; Lymph node harvest; Accurate staging; Station-specific lymph node submission

INTRODUCTION

Colorectal cancer is recognized as the third most common malignancy worldwide and ranks second in cancer-related mortality [1]. Surgical resection followed by adjuvant chemotherapy remains the cornerstone of treatment for locally advanced disease. According to the US National Comprehensive Cancer Network (NCCN) guidelines, TNM staging is essential for patient stratification, with adjuvant chemotherapy strongly advised for stage III and high-risk stage II patients. [2] Precise pathological staging, particularly through comprehensive lymph node evaluation, is therefore critical in guiding therapeutic decisions and improving clinical outcomes [3, 4]. Lymph node yield directly determines the accuracy of TNM staging in colorectal cancer, and nodal metastasis status plays a central role in decisions regarding adjuvant chemotherapy. Current guidelines mandate retrieval of ≥12 lymph nodes to optimize staging precision [2]. Nevertheless, 20% to 30% of resections fail to meet this threshold, which is an independent prognostic marker for poorer survival, underscoring the urgent need for standardized harvest protocols [5, 6].

Multiple variables, including patient age, obesity, specimen length, tumor characteristics, and neoadjuvant therapy, may compromise lymph node yield [7, 8]. Emerging predictive models that combine clinicopathological and radiomic features show promise for identifying nodal metastasis preoperatively, but they do not directly address optimization of harvest adequacy [9–11]. This study therefore aimed to identify modifiable surgical factors influencing lymph node retrieval in laparoscopic colorectal resection and to propose standardized protocols aimed at achieving guideline-recommended thresholds, ultimately addressing this important gap in staging accuracy.

METHODS

Ethics statement

This study was approved by the Institutional Medical Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (No. TJ-C20221211). Informed consent was obtained from all patients. The study procedures complied with the 1964 Declaration of Helsinki and its later revisions.

Study design and participants

This retrospective cohort study enrolled consecutive patients who underwent laparoscopic radical resection for colorectal adenocarcinoma at our institution between July 2019 and July 2024. Inclusion criteria required histologically confirmed adenocarcinoma with complete curative-intent surgical resection. Exclusion criteria comprised non-epithelial malignancies (e.g., lymphomas or neuroendocrine tumors), metastatic disease requiring palliative procedures such as stoma creation or bypass surgery, emergency operations for obstruction or perforation, multivisceral resections for tumor invasion, and incomplete clinicopathological documentation.

Data collection

We systematically collected 3 domains of data from laparoscopic colorectal cancer resections performed between 2019 and 2024. First, demographic information (age, sex, body mass index [BMI]), comorbidities (smoking or alcohol history, prior abdominal surgery), and tumor location were recorded. Second, clinicopathological characteristics were obtained, including differentiation grade, tumor size, TNM staging, lymph node yield and submission methodology, serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels, and operative details. Third, postoperative outcomes were documented, including Clavien-Dindo complications and hospitalization duration. This multidimensional dataset enabled a rigorous assessment of factors influencing lymph node harvest adequacy.

Primary endpoint and surgical procedures

Two attending surgeons from the gastrointestinal surgery department performed all laparoscopic resections in this study. Surgical procedures adhered to standardized D3 lymphadenectomy with complete mesocolic excision (CME), guided by mesenteric membrane anatomy. At the beginning of the study period in 2019, each surgeon had completed at least 50 independent laparoscopic colorectal cancer operations and was fully trained and proficient in the principles of D3+CME. To maintain consistency, all surgeons followed a uniform departmental protocol for D3+CME, the technical details of which have been previously described [12]. Key oncological principles requiring adequate bowel resection margins were strictly observed. For colonic tumors, both proximal and distal margins were planned to be at least 5 cm from the tumor edge to ensure oncologic safety. For low rectal cancers, a distal margin of at least 1 cm was considered acceptable when a 5-cm margin was not feasible, consistent with contemporary guidelines [2]. Tumor location determined the extent of resection, with en bloc removal of paracolic (first station), intermediate (second station), and central (third station, mesenteric root) lymph nodes during mesenteric dissection. For right-sided colon cancers, this included complete lymphatic dissection along the superior mesenteric vein, encompassing the roots of the ileocolic, right colic, and middle colic vessels. For left-sided and rectal cancers, high ligation of the inferior mesenteric artery at its aortic origin and corresponding venous division was performed to ensure complete central lymphadenectomy [12].

The primary endpoint was lymph node yield, stratified according to the guideline-mandated 12-node threshold (<12 nodes vs. ≥12 nodes) [2]. This binary outcome directly reflected surgical quality metrics and their influence on TNM staging accuracy.

Indication for station-specific lymph node submission

The implementation of station-specific lymph node submission was introduced as an institutional quality improvement initiative designed to optimize pathological staging accuracy. Initially applied selectively, the protocol was gradually expanded and became a standardized component of all laparoscopic colorectal cancer resections from late 2021 onward. As a result, its utilization was determined primarily by the date of surgery rather than patient characteristics, tumor features, or surgeon preference.

Protocol for station-specific lymph node submission

After resection, the fresh, unfixed surgical specimen was immediately transferred to a dedicated pathology dissection bench. Station-specific lymph node retrieval was systematically performed by 1 of 2 designated attending surgeons, who rotated assignments to maintain consistency. This approach leveraged their specialized understanding of colorectal vascular anatomy to achieve accurate anatomical compartmentalization.

The dissection protocol relied on established vascular landmarks to define lymph node stations. For rectal cancer specimens, station 1 included pararectal lymph nodes and those along the marginal artery; station 3 comprised apical lymph nodes at the origin of the inferior mesenteric artery (also designated station No. 253); and station 2 consisted of intermediate mesorectal lymph nodes between stations 1 and 3. For right colon cancer specimens, station 1 corresponded to paracolic nodes, station 3 encompassed central nodes at the roots of the ileocolic, right colic, and middle colic vessels along the superior mesenteric vein, and station 2 represented the intervening mesocolic nodes.

Dissected lymphoid and adipose tissue from each station was placed into separate pre-labeled containers for pathological examination. The bowel specimen containing the primary tumor was submitted separately for standard histopathological assessment, including evaluation of the circumferential resection margin. The final lymph node count for each case was defined as the sum of all nodes identified in stations 1, 2, and 3.

To illustrate the station-specific retrieval protocol, schematic and photographic images were prepared for both right colon and rectal cancer specimens. Fig. 1 depicts the anatomic dissection and submission workflow following right hemicolectomy, and Fig. 2 provides the corresponding guidance for a total mesorectal excision specimen. These figures serve as definitive references for the standardized methodology used in this study.

Statistical analysis

Statistical analyses were performed using IBM SPSS ver. 26.0 (IBM Corp) with standardized methodology. Continuous variables underwent normality testing; parametric data (mean±standard deviation) were compared using the Student t-test, and nonparametric data (median) were analyzed using the Mann-Whitney U-test. Categorical variables in frequency (%) were assessed using the chi-square or Fisher exact tests. Variables with P<0.1 in univariate logistic regression were included in multivariate analysis. The final multivariable logistic regression model identified independent predictors of lymph node yield, with statistical significance defined as P<0.05.

RESULTS

Baseline characteristics and lymph node harvest

The study cohort included 639 patients (mean age, 60.56±11.27 years; 400 male patients, 62.6%) who underwent laparoscopic colorectal resection. Tumor distribution comprised rectal (47.7%), sigmoid (20.5%), right colon (21.6%), left colon (8.6%), and transverse colon (1.6%) cancers. The median postoperative hospital stay was 8 days, and 6.4% of patients experienced postoperative complications.

A comparison of clinical characteristics and lymph node yield showed that patients who received neoadjuvant therapy had a significantly lower mean lymph node yield (11.45±7.79 vs. 18.41±8.26, P<0.001) and a lower lymph node metastasis rate (17.2% vs. 32.8%, P=0.08) compared with those who did not undergo neoadjuvant treatment. According to postoperative pathology reports, 331 patients (51.8%) underwent station-specific lymph node submission by the surgeons, including retrieval of first-, second-, and third-station nodes (paracolic, intermediate, and central compartments). Statistical analysis demonstrated that patients with station-specific submission achieved a significantly higher mean lymph node yield than those without it (20.93±9.15 vs. 15.13±6.37, P<0.001). In addition, significant differences in mean lymph node yield and lymph node metastasis rates were observed across subgroups defined by age, tumor location, and T category (all P<0.05) (Table 1).

Stratification by the 12-node threshold revealed clinically meaningful differences: age (P=0.017), sex (P=0.028), neoadjuvant therapy (P<0.001), tumor site (P=0.007), T category (P=0.032), lymphovascular invasion (P=0.025), microsatellite status (P=0.025), and station-specific submission (P<0.001) all emerged as significant discriminators (Table 2).

Analysis of factors influencing lymph node yield in laparoscopic colorectal cancer surgery

Univariate logistic regression identified several risk factors associated with a lymph node yield of fewer than 12 nodes in patients undergoing laparoscopic colorectal cancer surgery. These factors included age ≥65 years (χ²=4.279, P=0.039), male sex (χ²=4.748, P=0.029), receipt of neoadjuvant therapy (χ²=28.480, P<0.001), tumor site outside the right hemicolon (χ²=15.885, P<0.001), tumor invasion depth limited to T1–T2 (χ²=13.758, P<0.001), absence of lymphovascular invasion (χ²=4.823, P=0.028), microsatellite stability (χ²=4.226, P=0.040), and lack of station-specific lymph node submission (χ²=35.045, P<0.001) (Table 3). These results illustrate how patient- and tumor-related characteristics, along with surgical and pathological practices, influence lymph node harvest adequacy.

Multivariate logistic regression identified several independent predictors of a lymph node yield of fewer than 12 nodes. Neoadjuvant therapy (odds ratio [OR], 7.644; 95% confidence interval [CI], 3.169–18.435; P<0.001), tumor location outside the right hemicolon (OR, 4.445; 95% CI, 2.046–9.656; P<0.001), and shallow tumor invasion depth (T1–T2; OR, 2.024; 95% CI, 1.225–3.344; P=0.006) significantly increased the likelihood of inadequate lymph node retrieval. In contrast, station-specific lymph node submission was a strong protective factor that markedly reduced the risk of insufficient harvest (OR, 0.162; 95% CI, 0.095–0.278; P<0.001) (Table 4). These findings emphasize the pivotal role of operative and pathological techniques, together with tumor biology and prior treatment, in determining lymph node yield and ensuring optimal staging accuracy.

DISCUSSION

Adjuvant chemotherapy remains central to colorectal cancer management, with current guidelines emphasizing TNM staging as the foundation for therapeutic planning and prognostic assessment. Accurate staging relies on sufficient lymph node retrieval (≥12 nodes), yet clinical practice continues to exhibit substantial variability driven by patient, surgical, and pathological factors. Our large-scale analysis identifies 3 independent predictors of inadequate nodal yield (<12 nodes) following laparoscopic resection: exposure to neoadjuvant therapy, tumor location outside the right hemicolon, and early T stage (T1–T2) disease. These results are consistent with established biological and technical explanations. Notably, we demonstrate the effectiveness of a modifiable intervention: station-specific lymph node submission by surgeons significantly increases lymph node harvest (P<0.001), directly mitigating limitations in staging accuracy. This approach provides a more impactful solution than passive observational strategies and offers clinicians a practical method to enhance pathological assessment and strengthen downstream therapeutic decision-making.

Factors influencing lymph node retrieval in laparoscopic colorectal cancer surgery

Anatomic tumor location plays a critical role in determining lymph node harvest, with substantial evidence showing superior nodal yields in right-sided compared with left-sided colon cancers. Several studies have also reported that lymph node retrieval after rectal cancer surgery tends to be lower than after left-sided colon resection [13–15]. This disparity reflects both technical and biological determinants. Right hemicolectomy facilitates broader mesenteric dissection, incorporating the ileocolic and right colic lymphatic basins, whereas rectal resections are limited by pelvic anatomy and the increased histopathological complexity of isolating mesorectal nodes [16, 17]. Early T stage (T1–T2) tumors also yield fewer lymph nodes than advanced lesions (T3/T4), a phenomenon linked to reduced tumor-induced immune activation. Small and nonreactive lymph nodes in early-stage disease are more likely to be missed during both surgical dissection and pathological processing [18, 19]. Our findings support these mechanisms, demonstrating higher lymph node counts in right-sided laparoscopic resections and a direct association between increasing T stage and improved nodal retrieval. These results highlight the combined influence of anatomical accessibility and tumor biology on the quality of nodal assessment.

Impact of modern surgical techniques and multimodal therapy on lymph node retrieval in colorectal cancer

The evolution from open surgery to minimally invasive techniques, including laparoscopy and robotics, has transformed colorectal cancer care by reducing blood loss and improving perioperative recovery [20, 21]. Although these approaches achieve lymph node yields comparable to or exceeding those of open surgery, a notable paradox remains: approximately 20% to 30% of laparoscopic resections still fall short of the 12-node benchmark, compromising staging accuracy and subsequent decisions regarding adjuvant therapy [22–26]. This gap underscores the persistent mismatch between surgical capabilities and pathological optimization.

Simultaneously, the increasing use of neoadjuvant therapies, including chemoradiation and immunotherapy, introduces additional biological complexity. Preoperative treatment induces lymph node fibrosis and atrophy, reducing the number of retrievable nodes by 30% to 40% compared with upfront surgery [27–30]. Our data confirm this effect, establishing neoadjuvant therapy as an independent risk factor for inadequate nodal harvest. These insights highlight the need for a strategic shift that integrates refined surgical methods with enhanced pathology-level interventions capable of counteracting treatment-induced nodal depletion.

Actionable strategies to optimize lymph node harvest in laparoscopic colorectal cancer surgery

Addressing inadequate nodal retrieval requires a combination of proactive risk stratification and targeted procedural interventions. Established predictors, non–right-sided tumor location, early T stage, and neoadjuvant therapy exposure, enable early identification of patients who may benefit from intensified retrieval strategies.

Intraoperative lymphatic mapping using tracer agents such as methylene blue, nanocarbon, or indocyanine green has been shown to improve nodal detection by 25% to 40% through real-time visualization of lymphatic drainage pathways [6, 31–34]. Beyond such adjuncts, our findings demonstrate the substantial benefit of surgeon-directed compartmental specimen submission before formalin fixation. This technique increased mean nodal yield from 15.13±6.37 to 20.93±9.15 (P<0.001) and decreased inadequate harvest rates (<12 nodes) from 35.7% to 8.5%. The approach mitigates the effects of post-fixation tissue retraction and fragmentation, which are major challenges in traditional pathology workflows. Accordingly, surgeon-guided station-specific lymph node submission represents a clinically actionable, histologically validated strategy, particularly valuable for high-risk groups (e.g., patients with left-sided or rectal tumors, early T-stage disease, or prior neoadjuvant therapy) to mitigate staging inaccuracies arising from nodal retrieval deficits.

Clinical implications and limitations

This study confirms neoadjuvant therapy, tumor location outside the right hemicolon, and early T stage as independent predictors of inadequate lymph node retrieval, while also demonstrating the feasibility of compartment-based mapping as a yield-enhancing intervention. Nevertheless, these findings are constrained by inherent methodological limitations. The retrospective design does not allow definitive evaluation of surgeon-specific technical factors, including the thoroughness of dissection, in situ nodal identification, and operative decision-making, that may influence nodal yield. Additionally, although resection margins were oncologically sufficient, detailed measurements of specimen length and mesenteric extent were not routinely documented and therefore could not be analyzed, despite their potential relevance to lymph node harvest.

Our single-center setting further reflects institution-specific pathology practices, including fixed processing timelines and standardized fat-clearing techniques, as well as demographic homogeneity, which may limit generalizability to practice environments with different workflows or levels of pathologist experience. Unmeasured confounders such as BMI-related mesenteric fat distribution, subtle nuances in laparoscopic mesocolic dissection, and inter-pathologist variability in lymph node identification may also have influenced results. These considerations underscore the need for multicenter prospective studies that correlate intraoperative technical metrics with lymph node yield, compare pathology workflows across institutions, and evaluate compartment-mapping efficacy in relation to emerging tracer-assisted methods. Only through such standardized investigations can the observed 38% increase in lymph node yield be validated across broader clinical settings.

Conclusions

Our analysis identifies neoadjuvant therapy, non–right-sided tumor location, and early T stage as key predictors of suboptimal lymph node retrieval in laparoscopic colorectal cancer surgery. Station-specific lymph node submission enhances nodal yield and represents a practical surgeon-modifiable intervention warranting further validation. Successful implementation will require prospective standardization across diverse surgical teams and integration with tracer-based mapping strategies to counteract treatment-related reductions in nodal detectability. These findings support the development of risk-adapted specimen-handling protocols designed to preserve TNM staging accuracy amid the expanding use of minimally invasive and neoadjuvant treatment approaches.

ARTICLE INFORMATION

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

This study was supported by the Natural Science Foundation of Hainan Province (No. 821MS0855).

Author contributions

Conceptualization: all authors; Data curation: CG; Formal analysis: SZ; Funding acquisition: all authors; Investigation: all authors; Methodology: CG; Project administration: SZ; Writing–original draft: all authors; Writing–review & editing: all authors. All authors read and approved the final manuscript.

Fig. 1.

Surgical specimen and schematic of station-specific lymph node submission in right hemicolectomy. (A) The fresh, unfixed surgical specimen following a laparoscopic right hemicolectomy with complete mesocolic excision. The mesenteric window demonstrates the intact mesentery prior to dissection. (B) The same specimen opened along the antimesenteric border, revealing the primary tumor (T). (C) Clinical photograph illustrating the station‑specific lymph node dissection protocol. The lymph node basins are defined by vascular anatomy: station 1 (S1), paracolic lymph nodes along the marginal artery; station 2 (S2), intermediate mesocolic lymph nodes; and station 3 (S3), central lymph nodes at the vascular roots of the ileocolic, right colic, and middle colic vessels. (D) Practical implementation of the protocol, showing the separately submitted specimens for pathological processing, with the dissected lymph node stations (S1, S2, S3) in individual containers and the main bowel specimen prepared for standard histopathological evaluation.

Fig. 2.

Surgical specimen and schematic of station-specific lymph node submission in rectal cancer surgery. (A) Overview of the fresh, unfixed total mesorectal excision specimen following laparoscopic rectal cancer resection, demonstrating the intact mesorectum with its characteristic bilobed configuration. (B) The same specimen opened longitudinally along the antimesenteric border to reveal the primary tumor (T). (C) Clinical photograph illustrating the 3 lymph node stations used for station‑specific submission: station 1 (S1), pararectal or mesorectal lymph nodes adjacent to the bowel wall; station 2 (S2), intermediate lymph nodes within the main body of the mesorectum; and station 3 (S3), central or apical lymph nodes at the root of the inferior mesenteric artery. (D) The final separated specimens prepared for pathological assessment, showing individually containerized lymph node stations (S1, S2, S3) and the main rectal specimen submitted for histopathological evaluation.

Table 1.

Association between lymph node harvest outcomes and patient characteristics (n=639)

Variable	No. of lymph nodes harvested	P-value	Lymph node metastasis^a	P-value
Age		0.032		0.009
<65 yr (n=380)	18.73±8.75		137 (36.1)
≥65 yr (n=259)	17.27±7.88		68 (26.3)
Sex		0.132		0.269
Male (n=400)	17.75±8.39		122 (30.5)
Female (n=239)	18.79±8.49		83 (34.7)
Neoadjuvant therapy		<0.001		0.080
No (n=610)	18.45±8.34		200 (32.8)
Yes (n=29)	11.45±7.79		5 (17.2)
Body mass index (n=622)^b		0.138		0.160
<24 kg/m² (n=395)	18.41±8.26		121 (30.6)
≥24 kg/m² (n=227)	17.41±7.79		82 (36.1)
Tumor site		<0.001		0.056
Rectal (n=305)	16.83±8.02		100 (32.8)
Sigmoid (n=131)	19.19±10.16		33 (25.2)
Right colon (n=138)	21.01±7.89		55 (39.9)
Left colon (n=55)	15.58±5.13		16 (29.1)
Transverse colon (n=10)	18.70±8.44		1 (10.0)
T category		<0.001		<0.001
T1 (n=82)	15.70±7.46		9 (11.0)
T2 (n=87)	15.85±6.60		9 (10.3)
T3 (n=302)	19.55±9.07		102 (33.8)
T4 (n=168)	17.98±8.05		85 (50.6)
Station-specific lymph node submission		<0.001		0.295
No (n=308)	15.13±6.37		105 (34.1)
Yes (n=331)	20.93±9.15		100 (30.2)
Operation time		0.438		0.115
<240 min (n=297)	18.41±8.92		86 (29.0)
≥240 min (n=342)	17.89±8.00		119 (34.8)

Values are presented as mean±standard deviation or number (%).

^aData availability for each variable. ^bDue to missing data (n=17).

Table 2.

Baseline characteristics by lymph node yield group (n=639)

Characteristic	Lymph node yield		P-value
Characteristic	≥12 (n=532)	<12 (n=107)	P-value
Age (yr)	60.14±11.69	62.62±9.23	0.017
Sex			0.028
Male	323 (60.7)	77 (72.0)
Female	209 (39.3)	30 (28.0)
History of abdominal surgery			0.378
No	334 (62.8)	72 (67.3)
Yes	198 (37.2)	35 (32.7)
Body mass index (kg/m²)	22.84±3.17	23.01±2.94	0.634
Neoadjuvant therapy			<0.001
No	520 (97.7)	90 (84.1)
Yes	12 (2.3)	17 (15.9)
Tumor site			0.007
Rectum	239 (44.9)	66 (61.7)
Sigmoid	110 (20.7)	21 (19.6)
Right colon	131 (24.6)	7 (6.5)
Left colon	43 (8.1)	12 (11.2)
Transverse colon	9 (1.7)	1 (0.9)
Albumin (g/L)	39.51±4.07	39.85±4.21	0.427
Hemoglobin (g/L)	117.64±24.59	125.57±22.24	0.001
T category			0.032
T1	59 (11.1)	23 (21.5)
T2	66 (12.4)	21 (19.6)
T3	273 (51.3)	29 (27.1)
T4	134 (25.2)	34 (31.8)
N category			0.477
N0	359 (67.5)	76 (71.0)
N1	115 (21.6)	21 (19.6)
N2	58 (10.9)	10 (9.3)
Differentiation			0.250
Well	25 (4.7)	5 (4.7)
Moderate	359 (67.5)	79 (73.8)
Poor	148 (27.8)	23 (21.5)
Neural invasion			0.142
No	370 (69.5)	82 (76.6)
Yes	162 (30.5)	25 (23.4)
Lymphovascular invasion			0.025
No	423 (79.5)	95 (88.8)
Yes	109 (20.5)	12 (11.2)
Microsatellite instability status			0.025
pMMR	490 (92.1)	105 (98.1)
dMMR	42 (7.9)	2 (1.9)
Station-specific lymph node submission			<0.001
No	227 (42.7)	81 (75.7)
Yes	305 (57.3)	26 (24.3)
Operative time (min)	247.44±65.13	252.14±70.40	0.502
Postoperative complication			0.709
No	497 (93.4)	101 (94.4)
Yes	35 (6.6)	6 (5.6)
Length of hospital stay (day)	8 (7–10)	8 (8–10)	0.535

Values are presented as mean±standard deviation, number (%), or median (interquartile range).

pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.

Table 3.

Univariate analysis of factors associated with reduced (<12) lymph node yield (n=639)

Variable	No. of patients	OR (95% CI)	P-value
Age			0.039
<65 yr	380	1 (Reference)
≥65 yr	259	1.553 (1.023–2.357)
Sex			0.029
Male	400	1 (Reference)
Female	239	0.602 (0.382–0.950)
History of abdominal surgery			0.377
No	406	1 (Reference)
Yes	233	0.820 (0.528–1.274)
Body mass index (n=622)^a			0.831
<24 kg/m²	395	1 (Reference)
≥24 kg/m²	227	0.953 (0.614–1.479)
Neoadjuvant therapy			<0.001
No	610	1 (Reference)
Yes	29	8.185 (3.782–17.715)
Tumor site
Rectal	305	1 (Reference)
Sigmoid	131	0.691 (0.403–1.187)	0.181
Right colon	138	0.193 (0.086–0.434)	<0.001
Left colon	55	1.011 (0.504–2.026)	0.976
Transverse colon	10	0.402 (0.050–3.233)	0.392
T category			<0.001
T1–T2	169	1 (Reference)
T3–T4	470	0.440 (0.285–0.679)
Neural invasion			0.143
No	452	1 (Reference)
Yes	187	0.696 (0.429–1.130)
Lymphovascular invasion			0.028
No	518	1 (Reference)
Yes	121	0.490 (0.259–0.926)
Microsatellite instability status			0.040
pMMR	595	1 (Reference)
dMMR	44	0.222 (0.053–0.932)
Station-specific lymph node submission			<0.001
No	308	1 (Reference)
Yes	331	0.239 (0.149–0.384)
Operative time			0.315
<240 min	297	1 (Reference)
≥240 min	342	1.240 (0.815-1.887)

OR, odds ratio; CI, confidence interval; pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.

^aDue to missing data (n=17).

Table 4.

Multivariate logistic regression analysis of factors influencing reduced (<12) lymph node yield

Variable	β	Wald χ²	OR (95% CI)	P-value
Neoadjuvant therapy (yes vs. no)	2.034	20.503	7.644 (3.169–18.435)	<0.001
Tumor site (non–right colon^a vs. right colon)	1.492	14.197	4.445 (2.046–9.656)	<0.001
T category (T1–T2 vs. T3–T4)	0.706	7.592	2.024 (1.225–3.344)	0.006
Station-specific lymph node submission (yes vs. no)	–1.817	44.055	0.162 (0.095–0.278)	<0.001
Age (≥65 yr vs. <65 yr)	0.450	3.351	1.568 (0.969–2.540)	0.067
Sex (female vs. male)	–0.663	4.133	0.655 (0.425–1.108)	0.070
Lymphovascular invasion (yes vs. no)	–0.599	2.368	0.549 (0.256–1.178)	0.124
Microsatellite instability status (dMMR vs. pMMR)	–0.701	0.817	0.496 (0.108–2.270)	0.366

OR, odds ratio; CI, confidence interval; pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.

^aNon-right colon includes rectum, sigmoid, and left colon.

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Optimizing lymph node harvest in laparoscopic colorectal cancer: predictors and station-specific lymph node submission solutions

Ann Coloproctol. 2026;42(2):216-225. Published online April 27, 2026

DOI: https://doi.org/10.3393/ac.2025.01123.0160

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Figure

Optimizing lymph node harvest in laparoscopic colorectal cancer: predictors and station-specific lymph node submission solutions

Fig. 1. Surgical specimen and schematic of station-specific lymph node submission in right hemicolectomy. (A) The fresh, unfixed surgical specimen following a laparoscopic right hemicolectomy with complete mesocolic excision. The mesenteric window demonstrates the intact mesentery prior to dissection. (B) The same specimen opened along the antimesenteric border, revealing the primary tumor (T). (C) Clinical photograph illustrating the station‑specific lymph node dissection protocol. The lymph node basins are defined by vascular anatomy: station 1 (S1), paracolic lymph nodes along the marginal artery; station 2 (S2), intermediate mesocolic lymph nodes; and station 3 (S3), central lymph nodes at the vascular roots of the ileocolic, right colic, and middle colic vessels. (D) Practical implementation of the protocol, showing the separately submitted specimens for pathological processing, with the dissected lymph node stations (S1, S2, S3) in individual containers and the main bowel specimen prepared for standard histopathological evaluation.

Fig. 2. Surgical specimen and schematic of station-specific lymph node submission in rectal cancer surgery. (A) Overview of the fresh, unfixed total mesorectal excision specimen following laparoscopic rectal cancer resection, demonstrating the intact mesorectum with its characteristic bilobed configuration. (B) The same specimen opened longitudinally along the antimesenteric border to reveal the primary tumor (T). (C) Clinical photograph illustrating the 3 lymph node stations used for station‑specific submission: station 1 (S1), pararectal or mesorectal lymph nodes adjacent to the bowel wall; station 2 (S2), intermediate lymph nodes within the main body of the mesorectum; and station 3 (S3), central or apical lymph nodes at the root of the inferior mesenteric artery. (D) The final separated specimens prepared for pathological assessment, showing individually containerized lymph node stations (S1, S2, S3) and the main rectal specimen submitted for histopathological evaluation.

Fig. 1.

Fig. 2.

Optimizing lymph node harvest in laparoscopic colorectal cancer: predictors and station-specific lymph node submission solutions

Variable	No. of lymph nodes harvested	P-value	Lymph node metastasis^a	P-value
Age		0.032		0.009
<65 yr (n=380)	18.73±8.75		137 (36.1)
≥65 yr (n=259)	17.27±7.88		68 (26.3)
Sex		0.132		0.269
Male (n=400)	17.75±8.39		122 (30.5)
Female (n=239)	18.79±8.49		83 (34.7)
Neoadjuvant therapy		<0.001		0.080
No (n=610)	18.45±8.34		200 (32.8)
Yes (n=29)	11.45±7.79		5 (17.2)
Body mass index (n=622)^b		0.138		0.160
<24 kg/m² (n=395)	18.41±8.26		121 (30.6)
≥24 kg/m² (n=227)	17.41±7.79		82 (36.1)
Tumor site		<0.001		0.056
Rectal (n=305)	16.83±8.02		100 (32.8)
Sigmoid (n=131)	19.19±10.16		33 (25.2)
Right colon (n=138)	21.01±7.89		55 (39.9)
Left colon (n=55)	15.58±5.13		16 (29.1)
Transverse colon (n=10)	18.70±8.44		1 (10.0)
T category		<0.001		<0.001
T1 (n=82)	15.70±7.46		9 (11.0)
T2 (n=87)	15.85±6.60		9 (10.3)
T3 (n=302)	19.55±9.07		102 (33.8)
T4 (n=168)	17.98±8.05		85 (50.6)
Station-specific lymph node submission		<0.001		0.295
No (n=308)	15.13±6.37		105 (34.1)
Yes (n=331)	20.93±9.15		100 (30.2)
Operation time		0.438		0.115
<240 min (n=297)	18.41±8.92		86 (29.0)
≥240 min (n=342)	17.89±8.00		119 (34.8)

Characteristic	Lymph node yield		P-value
Characteristic	≥12 (n=532)	<12 (n=107)	P-value
Age (yr)	60.14±11.69	62.62±9.23	0.017
Sex			0.028
Male	323 (60.7)	77 (72.0)
Female	209 (39.3)	30 (28.0)
History of abdominal surgery			0.378
No	334 (62.8)	72 (67.3)
Yes	198 (37.2)	35 (32.7)
Body mass index (kg/m²)	22.84±3.17	23.01±2.94	0.634
Neoadjuvant therapy			<0.001
No	520 (97.7)	90 (84.1)
Yes	12 (2.3)	17 (15.9)
Tumor site			0.007
Rectum	239 (44.9)	66 (61.7)
Sigmoid	110 (20.7)	21 (19.6)
Right colon	131 (24.6)	7 (6.5)
Left colon	43 (8.1)	12 (11.2)
Transverse colon	9 (1.7)	1 (0.9)
Albumin (g/L)	39.51±4.07	39.85±4.21	0.427
Hemoglobin (g/L)	117.64±24.59	125.57±22.24	0.001
T category			0.032
T1	59 (11.1)	23 (21.5)
T2	66 (12.4)	21 (19.6)
T3	273 (51.3)	29 (27.1)
T4	134 (25.2)	34 (31.8)
N category			0.477
N0	359 (67.5)	76 (71.0)
N1	115 (21.6)	21 (19.6)
N2	58 (10.9)	10 (9.3)
Differentiation			0.250
Well	25 (4.7)	5 (4.7)
Moderate	359 (67.5)	79 (73.8)
Poor	148 (27.8)	23 (21.5)
Neural invasion			0.142
No	370 (69.5)	82 (76.6)
Yes	162 (30.5)	25 (23.4)
Lymphovascular invasion			0.025
No	423 (79.5)	95 (88.8)
Yes	109 (20.5)	12 (11.2)
Microsatellite instability status			0.025
pMMR	490 (92.1)	105 (98.1)
dMMR	42 (7.9)	2 (1.9)
Station-specific lymph node submission			<0.001
No	227 (42.7)	81 (75.7)
Yes	305 (57.3)	26 (24.3)
Operative time (min)	247.44±65.13	252.14±70.40	0.502
Postoperative complication			0.709
No	497 (93.4)	101 (94.4)
Yes	35 (6.6)	6 (5.6)
Length of hospital stay (day)	8 (7–10)	8 (8–10)	0.535

Variable	No. of patients	OR (95% CI)	P-value
Age			0.039
<65 yr	380	1 (Reference)
≥65 yr	259	1.553 (1.023–2.357)
Sex			0.029
Male	400	1 (Reference)
Female	239	0.602 (0.382–0.950)
History of abdominal surgery			0.377
No	406	1 (Reference)
Yes	233	0.820 (0.528–1.274)
Body mass index (n=622)^a			0.831
<24 kg/m²	395	1 (Reference)
≥24 kg/m²	227	0.953 (0.614–1.479)
Neoadjuvant therapy			<0.001
No	610	1 (Reference)
Yes	29	8.185 (3.782–17.715)
Tumor site
Rectal	305	1 (Reference)
Sigmoid	131	0.691 (0.403–1.187)	0.181
Right colon	138	0.193 (0.086–0.434)	<0.001
Left colon	55	1.011 (0.504–2.026)	0.976
Transverse colon	10	0.402 (0.050–3.233)	0.392
T category			<0.001
T1–T2	169	1 (Reference)
T3–T4	470	0.440 (0.285–0.679)
Neural invasion			0.143
No	452	1 (Reference)
Yes	187	0.696 (0.429–1.130)
Lymphovascular invasion			0.028
No	518	1 (Reference)
Yes	121	0.490 (0.259–0.926)
Microsatellite instability status			0.040
pMMR	595	1 (Reference)
dMMR	44	0.222 (0.053–0.932)
Station-specific lymph node submission			<0.001
No	308	1 (Reference)
Yes	331	0.239 (0.149–0.384)
Operative time			0.315
<240 min	297	1 (Reference)
≥240 min	342	1.240 (0.815-1.887)

Variable	β	Wald χ²	OR (95% CI)	P-value
Neoadjuvant therapy (yes vs. no)	2.034	20.503	7.644 (3.169–18.435)	<0.001
Tumor site (non–right colon^a vs. right colon)	1.492	14.197	4.445 (2.046–9.656)	<0.001
T category (T1–T2 vs. T3–T4)	0.706	7.592	2.024 (1.225–3.344)	0.006
Station-specific lymph node submission (yes vs. no)	–1.817	44.055	0.162 (0.095–0.278)	<0.001
Age (≥65 yr vs. <65 yr)	0.450	3.351	1.568 (0.969–2.540)	0.067
Sex (female vs. male)	–0.663	4.133	0.655 (0.425–1.108)	0.070
Lymphovascular invasion (yes vs. no)	–0.599	2.368	0.549 (0.256–1.178)	0.124
Microsatellite instability status (dMMR vs. pMMR)	–0.701	0.817	0.496 (0.108–2.270)	0.366

Table 1. Association between lymph node harvest outcomes and patient characteristics (n=639)

Values are presented as mean±standard deviation or number (%).

Data availability for each variable. ^bDue to missing data (n=17).

Table 2. Baseline characteristics by lymph node yield group (n=639)

Values are presented as mean±standard deviation, number (%), or median (interquartile range).

pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.

Table 3. Univariate analysis of factors associated with reduced (<12) lymph node yield (n=639)

OR, odds ratio; CI, confidence interval; pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.

^aDue to missing data (n=17).

Table 4. Multivariate logistic regression analysis of factors influencing reduced (<12) lymph node yield

OR, odds ratio; CI, confidence interval; pMMR, proficient mismatch repair; dMMR, deficient mismatch repair.