Robotic tumor-specific mesocolic excision with D3 lymph node dissection for descending colon cancer

Abstract

We present a robotic approach to tumor-specific mesocolic excision with D3 lymph node dissection for descending colon cancer. This technique is based on three established principles: the radical en bloc lymphadenectomy of Japanese D3 lymph node dissection, the fascial plane-oriented sharp dissection of Western complete mesocolic excision, and the tumor-adapted rationale of tumor-specific partial mesorectal excision in rectal cancer. Key procedural elements include dissection along the embryological mesocolic plane, standardized 10-cm proximal and distal margins, en bloc lymphadenectomy of stations 231 (paracolic), 232 (intermediate), and 253 (apical), selective ligation of tumor-feeding arteries such as the left colic artery and sigmoid arteries, and preservation of the inferior mesenteric artery trunk to maintain perfusion to the distal bowel. Robotic assistance enables meticulous vascular control and precise mesocolic plane preservation. Between May 2023 and May 2025, 20 patients underwent this procedure without conversions to open surgery or intraoperative complications. The median age was 57 years (IQR 45–69), and median BMI was 22.6 kg/m² (IQR 19.6–24.6). The median blood loss was 72 mL (IQR 42–150), and median number of harvested lymph nodes was 27 (IQR 19–35), including 5 apical nodes (IQR 2–7). One patient experienced Clavien–Dindo grade IIIa ileus; no anastomotic leaks were observed. The median postoperative hospital stay was 7 days. At the last follow-up (median 19 months), all patients were alive without recurrence. These findings highlight tumor-specific mesocolic excision with D3 lymph node dissection as a safe, reproducible, and technically robust strategy for oncological dissection that may help refine the standard of care for descending colon cancer in the era of robotic surgery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10151-026-03360-2.

Introduction

Robotic surgery is increasingly used in colorectal cancer, offering enhanced precision, dexterity, and ergonomic advantages, particularly in anatomically challenging regions. However, a standardized approach for descending colon cancer—one of the least common subtypes—remains lacking. Currently, two principal paradigms guide oncologic colectomy: Japanese D3 lymph node dissection and the Western concept of complete mesocolic excision (CME) [1, 2]. D3 lymph node dissection entails en bloc removal of paracolic (231), intermediate (232), and apical (253) lymph nodes, with approximately 10-cm proximal and distal bowel margins [3, 4]. In contrast, CME, introduced by Hohenberger et al. [5], emphasizes sharp dissection along embryological planes to remove the mesocolon as an intact fascial envelope, often resulting in longer bowel resections [1]. Both aim to maximize lymphovascular clearance, but differ in technical emphasis [2]. As noted by Hohenberger [6], D3 lymph node dissection prioritizes comprehensive nodal dissection but did not historically emphasize mesocolic plane preservation, particularly during the era of open surgery favoring lateral-to-medial mobilization [7]. Indeed, current Japanese classifications [4] and guidelines [3] do not explicitly mandate plane-oriented mesocolic excision for colon cancer. However, with widespread adoption of laparoscopic and robotic platforms, the medial-to-lateral approach has become standard in Japan, naturally facilitating precise dissection along embryological planes and narrowing practical differences with CME.

The conceptual underpinnings of CME closely mirror total mesorectal excision (TME), which revolutionized rectal cancer surgery by adhering strictly to embryological planes and demonstrating superior oncologic outcomes [8]. A more tailored approach—tumor-specific mesorectal excision (TSME)—defines resection extent by tumor location, sparing the uninvolved mesorectum without compromising oncologic outcomes [9, 10]. This paradigm has sparked an interest in applying analogous tumor-specific strategies to colon cancer. Recent prospective evidence supports the oncologic adequacy of fixed 10-cm proximal and distal margins in colon cancer [11], challenging the need for extended bowel resections typical of classic CME.

Although the term “tumor-specific mesocolic excision” has been described in recent literature [12–14] and a clinical trial registration entry [15], detailed descriptions of its standardized application in the robotic setting, particularly for descending colon cancer, remain limited. In this study, we adopt the term “tumor-specific mesocolic excision”, and present a structured robotic approach incorporating D3 lymph node dissection for descending colon cancer. This approach is designed to achieve anatomical precision, oncological adequacy, and technical reproducibility. Rather than introducing an entirely novel technique, our strategy builds upon three well-established principles: the radical lymphadenectomy inherent to Japanese D3 lymph node dissection, the meticulous fascial plane-oriented mobilization central to CME, and the tumor-adapted philosophy exemplified by rectal TSME. Our approach involves sharp embryological plane dissection, standardized 10-cm proximal and distal margins, en bloc retrieval of regional lymph nodes (stations 231, 232, and 253), preservation of the inferior mesenteric artery (IMA) trunk to maintain distal perfusion, and selective ligation of tumor-feeding branches such as the left colic artery (LCA) and sigmoid arteries (Fig. 1). By clearly defining and illustrating this unified concept, we aim to advance its standardization and facilitate broader adoption in the era of minimally invasive surgery, ultimately setting a new benchmark for precise and oncologically sound treatment of descending colon cancer.

Fig. 1.

Conceptual paradigms of oncologic resection for descending colon cancer. a The Western CME concept: Western approach of complete mesocolic excision, emphasizing sharp dissection along the mesocolic plane with central vascular ligation. b The traditional Japanese D3 lymphadenectomy approach: Japanese D3 lymph node dissection, characterized by systematic en bloc removal of regional lymph nodes including apical nodes at station 253. c The integrated strategy proposed in the present study: Proposed tumor-specific mesocolic excision combined with D3 lymph node dissection, integrating precise mesocolic plane dissection, en bloc removal of regional lymph nodes with selective vascular ligation, and standardized 10-cm proximal and distal margins tailored to tumor location

Surgical technique

The patient is placed in the lithotomy position on the operating table set at 15° Trendelenburg and 10° right tilt. The procedure is performed using the da Vinci Xi^® system (Intuitive Surgical Inc., Sunnyvale, CA, USA), with six 8-mm robotic trocars strategically positioned (Supplementary Fig. 1).

Medial-to-lateral mobilization of the left mesocolon

After confirming the tumor location and absence of metastasis (Fig. 2a), sharp dissection is performed along the embryological plane from the sacral promontory toward the IMA root. Critical retroperitoneal structures, including the ureter, gonadal vessels, and hypogastric nerves, are identified and preserved under high-definition 3D visualization (Fig. 2b). Unlike high vascular ligation, the IMA trunk is preserved, with only tumor-feeding branches targeted to maintain distal perfusion.

Fig. 2.

Robotic medial-to-lateral mobilization and skeletonization of the left mesocolon. a Intraoperative exploration confirming absence of peritoneal or distant metastasis. Tumor located in the mid-descending colon with swollen lymph nodes (arrowheads) along the left colic artery (LCA) (arrow). b Sharp medial-to-lateral dissection along the embryological mesocolic plane with preservation of critical retroperitoneal structures including the ureter, gonadal vessels, and hypogastric nerves. Arrow: inferior mesenteric artery (IMA). c Skeletonization of the IMA from its origin with en bloc lymphadenectomy including apical nodes (253) (arrowhead). d Preservation of the IMA–superior rectal artery trunk with selective identification of tumor-feeding vessels; in this case, both the LCA (*) and sigmoid arteries (**) are noted

Skeletonization of the IMA and lymph node dissection (station 253)

The IMA is skeletonized from its origin, preserving its trunk while removing surrounding lymphatic tissue, including apical nodes at station 253, en bloc with the mesocolon (Fig. 2c). Bilateral superior hypogastric nerves are also preserved, ensuring both oncologic thoroughness and autonomic function.

Selective vascular ligation and mesocolic separation

The vascular anatomy from the IMA root to its distal branches is carefully assessed by isolating the IMA–superior rectal artery (SRA) trunk (Fig. 2d). Tumor-feeding vessels, such as the left colic artery (LCA) and sigmoid arteries, are selectively ligated based on preoperative mapping using 3D CT angiography-based vascular reconstruction and intraoperative findings (Figs. 3a, b). During this process, the perivascular nerve plexus surrounding the IMA is intentionally resected to enhance exposure of vascular branches and minimize the risk of inadvertent injury. Following ligation, lymphatic tissue including stations 253 and 232 is removed en bloc with the mesocolon. The caudal mesenteric dissection line is then determined by tumor location, and the mesentery is incised to expose the inferior mesenteric vein (IMV) (Fig. 3c), which is divided peripherally and then centrally near the pancreatic border (Fig. 3d). This completes the vascular dissection, fully separating the left mesocolon—including stations 253 and 232—from the preserved IMA–SRA trunk. Furthermore, for mid and distal descending colon cancers, when the resection field includes a sigmoid artery, we perform ligation of the relevant sigmoid artery together with dissection of station 242 lymph nodes. Distal mesocolon/mesorectal mobilization is carried out approximately 5 cm caudal to the sacral promontory. This degree of mesorectal mobilization allows the distal bowel to be easily exteriorized through a small umbilical incision and facilitates extracorporeal bowel division and anastomosis.

Fig. 3.

Robotic selective vascular ligation and management of the inferior mesenteric vein (IMV). a Division of the left colic artery (*). b Identification of two sigmoid arteries (**) as tumor feeders requiring ligation at their origins. c Peripheral ligation of the IMV at the planned distal mesenteric resection margin following arterial division. Arrow: IMV. d Proximal ligation of the IMV at the inferior border of the pancreas, corresponding to the cranial mesenteric resection margin. Clip denotes the ligation site; arrow: IMV

Splenic flexure mobilization

The patient is repositioned in a left-side-up (10° right tilt), anti-Trendelenburg tilt (− 5°), and the port configuration is adjusted as shown in Supplementary Fig. 1. The greater omentum is divided to enter the omental bursa, and attachments such as the splenocolic and phrenicocolic ligaments are divided. The transverse mesocolon is mobilized along the inferior pancreatic border to fully release the splenic flexure, ensuring sufficient length for a tension-free anastomosis.

Specimen extraction via mini-laparotomy

Once safe exteriorization is confirmed, the robot is undocked. A 5-cm midline mini-laparotomy is created by vertically extending the umbilical incision. The specimen is extracted using a wound protector to minimize contamination. The left mesocolon, including stations 253 and 232, is verified on the specimen by identifying previously placed Hem-o-lok^® clips (Teleflex Medical, Research Triangle Park, NC, USA).

Tumor-specific mesocolic excision and reconstruction (extracorporeal)

Under direct vision, proximal and distal transection sites are marked 10 cm from the tumor using a sterile ruler. Sharp dissection along the mesocolic plane is then performed between these points, tailored to tumor location to secure adequate oncologic margins. Prior to bowel transection, perfusion is assessed using Firefly fluorescence imaging with indocyanine green to ensure adequate microvascular flow. The colon is then transected, and the tumor-bearing segment along with the corresponding mesocolon and regional lymphatic tissue is resected en bloc. Bowel continuity is restored by constructing a functional end-to-end anastomosis with linear staplers.

Mesenteric defect closure

The robot is re-docked to close the mesenteric defect between the proximal and distal mesenteric edges; this is to prevent internal herniation, which has been reported to occur in approximately 1.28% of cases after left hemicolectomy [16]. A continuous barbed suture (V-Loc™: Medtronic, Minneapolis, MN, USA) is used to achieve secure, tension-free closure. See the video in Electronic Supplementary Material S1, which demonstrates the tumor-specific mesocolic excision with D3 lymph node dissection procedure.

Variations in tumor-feeding arteries and corresponding vascular strategies

A tailored vascular approach is essential, as the arterial supply to the tumor can vary considerably. When the ascending LCA is the sole feeder due to a sigmoid branch supplying the uninvolved bowel, the LCA is divided distal to this branch to preserve perfusion to the remaining colon (see the video in Electronic Supplementary Material 2). In cases where an accessory middle colic artery (MCA) contributes to the tumor’s blood supply, this vessel is divided near the inferior border of the pancreas with en bloc resection of the surrounding mesocolic tissue.

Discussion

In this report, we present tumor-specific mesocolic excision with D3 lymph node dissection as a robotic approach tailored to descending colon cancer. This concept integrates three established oncologic principles: the radical en bloc lymphadenectomy of Japanese D3 lymph node dissection (Fig. 1b), the sharp plane-oriented mobilization characteristic of CME (Fig. 1a), and the tumor-adapted strategy analogous to TSME in rectal cancer. Essential elements include precise mesocolic dissection along embryological planes, central ligation of tumor-feeding arteries (LCA and sigmoid branches), standardized 10-cm proximal and distal margins, and preservation of the IMA–SRA trunk to maintain distal perfusion (Fig. 1c). Among these, skeletonizing the IMA while sparing its trunk is particularly challenging and benefits from robotic high-definition 3D visualization and articulating instruments, which enable the surgeon to approach vessels at optimal angles, allowing for meticulous vascular control and sharp dissection directly along the vessel surface. This capability makes complete skeletonization of the IMA trunk and intentional resection of the perivascular nerve plexus both easier and safer compared with the use of straight laparoscopic instruments.

While the terminology “tumor-specific mesocolic excision” has been previously introduced [12–15], prior reports have described its application in various clinical contexts.

In the present study, we focus on providing a detailed, procedure-oriented description of its robotic implementation for descending colon cancer. Specifically, our approach incorporates (i) mesocolic plane-based dissection consistent with the principles of CME, (ii) systematic D3 lymph node dissection, and (iii) vascular management strategies tailored to the anatomy of the descending colon. By presenting these elements in a stepwise and anatomically defined manner, this report aims to enhance technical clarity and support reproducibility in the robotic setting.

Between May 2023 and May 2025, 20 consecutive patients with descending colon cancer underwent this procedure at our institution with no conversions or intraoperative complications. Patient characteristics are shown in Table 1. The median age was 57 years (IQR 45–69), median BMI was 22.6 kg/m² (IQR 19.6–24.6), median operative time was 367 min (IQR 351–439), and median blood loss was 72 mL (IQR 42–150). Only one patient developed Clavien–Dindo grade IIIa ileus; no anastomotic leaks occurred. Median postoperative stay was 7 days (IQR 7–8). A median of 27 lymph nodes (IQR 19–35), including 5 at station 253 (IQR 2–7), were retrieved. The number of positive lymph nodes was 0.5 (IQR 0–1.75) among the 27 (IQR 19–35) retrieved lymph nodes. Metastasis to station 253 occurred in one case, and nodal involvement along an accessory MCA in another, underscoring the oncologic necessity of thorough central lymph node dissection. At the last follow-up, all patients were alive without recurrence, including two stage IV patients who had undergone metastasectomy. These findings highlight the safety, feasibility, and oncologic adequacy of this technique, and its capacity to achieve comprehensive lymph node dissection with a low complication rate in the context of minimally invasive robotic surgery.

Table 1.

Patient characteristics (n = 20)

Sex	Male: 9, Female: 11
Age	57 years (IQR 45–69)
ASA-PS	Class I: 4, Class II: 16
BMI	22.6 kg/m2 (IQR 19.6–24.6)
Tumor location	Proximal D: 7, Mid-D: 6, Distal D: 7
Vascular division	LCA: 6, LCA and accessory middle colic artery: 2, LCA and sigmoid artery: 9, LCA distal to a sigmoid branch (ascending LCA): 2, LCA distal to a sigmoid branch (ascending LCA) and accessory middle colic artery: 1
Operative time	367 min (IQR 351–439)
Blood loss	72 mL (IQR 42–150)
Number of harvested lymph nodes	27 (IQR 19–35), including 5 apical nodes (IQR 2–7)
Number of positive lymph nodes	0.5 (IQR 0–1.75)
Postoperative hospital stay	7 days (IQR 7–8)
Stage	I: 4, II: 6, III: 8, IV: 2
Follow-up period	19 months (IQR 4–28)*

ASA-PS ASA physical status classification system, BMI body mass index, IQR interquartile range

*At the last follow-up, all patients were alive without recurrence, including two stage IV patients who had undergone metastasectomy

A notable feature of this procedure is the intentional resection of the perivascular nerve plexus surrounding the IMA (Figs. 2, 3). While not routinely performed in conventional D3 lymph node dissection, emerging data reveal abundant lymphatic ducts within the IMA sheath [17], suggesting a route for micrometastasis. Beyond the oncologic rationale, this maneuver is also technically advantageous. By directly exposing the IMA trunk, branches such as the left colic artery (LCA) and sigmoid arteries are clearly visualized, facilitating the selective ligation of these branches while reducing the risk of inadvertent vascular injury. For example, the root of the LCA, the origins of the sigmoid arteries, and even sigmoid branches arising from the LCA can be safely identified in this manner. Importantly, perivascular nerve resection is standard during IMA root ligation in sigmoidectomy or anterior resection without major sequelae. Therefore, we regard this step as both oncologically justified and technically advantageous in robotic surgery for descending colon cancer.

This study has several limitations. First, it was conducted at a single center with a non-comparative design and lacks long-term oncologic outcome data. Although our short-term results support the feasibility and safety of this procedure, larger multicenter studies are required to validate its oncologic equivalence and assess reproducibility. Second, this study employed a six-port approach, which reflects a technique transferred from the da Vinci Si to the Xi platform. In contrast, the currently accepted standard is a four-port straight-line approach using 8-mm trocars, which may provide comparable outcomes with fewer access sites. Thus, our method may not represent the most up-to-date port placement strategy, and further optimization could be achieved by adopting the four-port technique. Third, we utilized the two-right-hand approach, which is widely practiced in Japan for robotic colorectal surgery and facilitates efficient tissue handling during mesocolic dissection. However, alternative configurations, such as the two-left-hand approach reported in Western practice, have also been described, and the optimal strategy remains to be determined. Fourth, the highest BMI in our cohort was 28. Although we believe that this technique can be applied to patients with higher BMI with careful port placement and appropriate patient selection, further investigation is warranted to confirm its safety and feasibility in this population. Finally, in our series, extracorporeal anastomosis was performed through a vertical midline umbilical incision rather than intracorporeal anastomosis with suprapubic specimen extraction. Particularly in patients with higher BMI, the latter approach may represent a reasonable alternative.

Conclusion

We described a procedure involving robotic tumor-specific mesocolic excision with D3 lymph node dissection for descending colon cancer, uniting principles of Japanese D3 lymph node dissection, CME, and tumor-specific mesorectal excision. The present study does not aim to claim the invention of new individual operative steps. Rather, it provides a clearly defined conceptual framework integrating mesocolic plane-oriented dissection with standardized D3 lymph node dissection for descending colon cancer. By systematically combining these oncologic principles, this approach may facilitate a more reproducible and anatomically consistent surgical strategy. Such conceptual clarification may help establish a practical framework for the standardization of robotic surgery for descending colon cancer.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

DS was responsible for the study concept and design, and drafted the manuscript. JM, SM, JI, GI, and NS participated in patient care and were involved in revising the manuscript. All authors conceptualized this surgery and conducted the literature searches. All authors read and approved the final manuscript.

Funding

Open Access funding provided by The University of Tokyo. No funding was received for this study.

Data availability

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.

Declarations

Conflict of interest

The authors declare no competing interests.

Ethical approval

Ethics approval was obtained from the Institutional Review Board (IRB) of the Institute of Medical Science, The University of Tokyo (IRB code 2022-9-0524). The need for written consent was waived.

Informed consent

Informed consent was waived due to the retrospective nature of the study and the complete anonymization of all patient data.