An anatomical, histopathological, and molecular biological function study of the fascias posterior to the interperitoneal colon and its associated mesocolon: their relevance to colonic surgery

The retrocolic fascial system revisited for right hemicolectomy with complete mesocolic excision based on anatomical terminology: do we need the eponyms Toldt, Gerota, Fredet and Treitz?

AIM

Right hemicolectomy with complete mesocolic excision (CME) requires the removal of an intact mesocolic envelope. The study aimed to determine, on the basis of macroscopic and microscopic anatomical studies, the optimal surgical dissection planes for CME to preserve fascial integrity. Unequivocal anatomical nomenclature was applied to describe the retrocolic fascial system and compared to frequently used eponyms (Toldt, Gerota, Fredet, Treitz).

METHOD

Stepwise macroscopic dissections, cross-section studies and histological analysis were performed on body donors to identify the components of the retrocolic fascial system. Based on these anatomical findings, the optimal surgical dissection planes for CME were validated in laparoscopic training courses on body donors and in robot-assisted surgical procedures in patients.

RESULTS

The mesocolic tissue and lymphovascular pedicles were enveloped by the ventral and dorsal mesocolic leaf (mesocolic fascia). The mesocolic fascia was attached to the parietal peritoneal fascia ('fascia of Toldt') along the parieto-mesocolic interface, and further cranially to the pre-duodenopancreatic fascia along the mesocolic-duodenopancreatic interface ('space of Fredet'). Dorsally, the parietal peritoneal fascia was separated from the anterior renal fascia ('fascia of Gerota') by the parieto-renal interface. Dissection along this interface in front of the anterior renal fascia followed by incision of the parietal peritoneal fascia at the duodenal border and opening the mesocolic-duodenopancreatic interface yielded the best macroscopic appearance of specimens and was considered optimal for CME.

CONCLUSION

The retrocolic fascial system as well as the surgical dissection planes for CME can be described by clearly defined anatomical terms rather than potentially confusing eponyms.

Does cranial-medial mixed dominant approach have a unique advantage for laparoscopic right hemicolectomy with complete mesocolic excision?

BACKGROUND

Complete mesocolic excision (CME) with central vascular ligation (CVL) was proposed by Hohenberger in 2009. The CME principle has gradually become the technical standard for colon cancer surgery. How to achieve CME with CVL in laparoscopic right hemicolectomy (LRH) is controversial, and a unified standard approach is not yet available. In recent years, the authors’ team has integrated the theory of membrane anatomy, tried to combine the cephalic approach with the classic medial approach (MA) for technical optimization, and proposed a cranial-medial mixed dominant approach (CMA).

AIM

To explore the feasibility of operational approaches for LRH with CME.

METHODS

In this retrospective cohort study, the clinical data of 57 patients with right-sided colon cancer (TNM stage I, II, or III) who underwent LRH with CME from January 2016 to June 2020 were collected and summarized. There were 31 patients in the traditional MA group and 26 in the CMA group.

RESULTS

There were no significant differences in baseline data between the two groups. The operation was shorter and the number of lymph nodes dissected was higher in the CMA group than in the MA group, but there was no significant difference in the number of positive lymph nodes, intraoperative blood loss, postoperative exhaust time, feeding time, postoperative hospital stay or postoperative complication incidence.

CONCLUSION

Our study shows that the CMA is a safe and feasible procedure for LRH with CME and has a unique advantage.

International Guidelines for Veterinary Tumor Pathology: A Call to Action

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal methodological standardization for assessing tumors in veterinary medicine, with few attempts to validate published protocols and grading schemes. The current article attempts to address these shortcomings by providing standard guidelines for tumor assessment parameters and protocols for evaluating specific tumor types. More detailed information is available in the Supplemental Files, the intention of which is 2-fold: publication as part of this commentary, but more importantly, these will be available as "living documents" on a website (www.vetcancerprotocols.org), which will be updated as new information is presented in the peer-reviewed literature. Our hope is that veterinary pathologists will agree that this initiative is needed, and will contribute to and utilize this information for routine diagnostic work and oncologic studies. Journal editors and reviewers can utilize checklists to ensure publications include sufficient detail and standardized methods of tumor assessment. To maintain the relevance of the guidelines and protocols, it is critical that the information is periodically updated and revised as new studies are published and validated with the intent of providing a repository of this information. Our hope is that this initiative (a continuation of efforts published in this journal in 2011) will facilitate collaboration and reproducibility between pathologists and institutions, increase case numbers, and strengthen clinical research findings, thus ensuring continued progress in veterinary oncologic pathology and improving patient care.

The large intestine from fetal period to adulthood and its impact on the course of colonoscopy

The human large intestine in the living adult has a total length of about 1300 mm, ranging from 1100 to 2108 mm. The development of the gut continues after birth, up to the age 4-5. The large intestine ascends at the beginning in the right abdominal quadrant, then it traverses the abdominal cavity, and finally it descends to the anus. The left and right colic flexures are the basic flexions between the transverse, ascending and descending colon, respectively. Additionally, there are secondary bendings between intestinal segments. The angles between the neighbouring parts can vary between examined subjects. Most of the angulations can be found in the transverse (range 2-9) and sigmoid colon (range 1-9), making them the most troublesome parts to pass with a colonoscope. Colonoscopy (usually performed in the left lateral or supine position) is one of the most important examination of the large intestine mucus membrane. During this procedure the endoscope is passed through the colon into the cecum or terminal ilium. The individual anatomical features (tortuosity, supernumerary loops and elongation) may slow down or interfere with the progress of the scope. We summarize current knowledge on the human large intestine from the fetal period to adulthood and carve out some aspects that are currently less known to colonoscopists.

Green indocyanine fluorescence in robotic abdominal surgery

Fluorescent imaging with indocyanine green (ICG) is an emerging technology that is gaining acceptance for being a valid tool in surgeons' decision making. ICG binds to plasma lipoproteins if injected intravenously and, when excited by near-infrared light, provides anatomic information about organs vascularization and tissues perfusion. If injected in tissues, it migrates in the lymphatic system, therefore enabling the identification of lymphatic draining pathways of different organs. In this paper we address specific applications of ICG fluorescence in robotic general surgery.

The Radical Extent of lymphadenectomy - D2 dissection versus complete mesocolic excision of LAparoscopic Right Colectomy for right-sided colon cancer (RELARC) trial: study protocol for a randomized controlled trial

Background

The extent of lymphadenectomy during laparoscopic right colectomy can affect the oncological outcome and the safety of surgery. The principle of complete mesocolic excision (CME) has been gradually accepted and increasingly applied by colorectal surgeons. The aim of this study is to investigate whether extended lymphadenectomy (CME) in laparoscopic colectomy could improve the oncological outcomes of patients with right-sided colon cancers, compared with D2 lymphadenectomy.

Methods/design

The Radical Extent of lympadenectomy: D2 dissection versus complete mesocolic excision of LAparoscopic Right Colectomy for right-sided colon cancer (RELARC) study is a prospective, multicenter, randomized controlled trial in which 1072 eligible patients with right-sided colon cancers will be randomly assigned to the CME group or the D2 dissection group during laparoscopic right colectomy. Inclusion criteria are locally advanced colon cancers situated from the cecum to the right third of the transverse colon and clinically staged as T2-4aN0M0 or TanyN + M0. The primary endpoint of this trial is 3-year disease-free survival. Secondary endpoints include 3-year overall survival, postoperative complication rates, perioperative mortality rates, and rates of positive central lymph nodes (the station 3 nodes).

Discussion

The RELARC trial is a prospective, multicenter, randomized controlled trial that will provide evidence on the optimal extent of lymphadenectomy during laparoscopic right colectomy in terms of better oncological outcome and operation safety.

Trial registration

ClinicalTrials.gov: NCT02619942. Registered on 29 November 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1710-9) contains supplementary material, which is available to authorized users.

Surgery along the embryological planes for colon cancer: a systematic review of complete mesocolic excision

BACKGROUND

Complete mesocolic excision (CME) for colonic cancer offers a surgical specimen of higher quality, with higher number of lymph nodes compared to conventional colectomy. However, evidence on oncological outcomes is limited. The aim of the present study is to review recent literature and provide more information regarding the effect of CME colectomy on short- and long-term outcomes.

METHOD

PubMed and MEDLINE databases were searched, and articles in English reporting data on CME were reviewed. Intraoperative events; postoperative morbidity and mortality; histopathological characteristics, including macroscopic assessment, number, and status of retrieved lymph nodes; and oncological outcomes were the end-points.

RESULTS

Thirty-two studies were analyzed. As regards the macroscopic assessment, a larger specimen (p = 0.02) that contains a higher number of lymph nodes (p < 0.00001) is acquired after CME. Two studies report a higher disease-free survival, in stage I and II and particularly in stage III disease after CME. CME by laparoscopy offers comparable outcomes, as regards intraoperative blood loss and immediate postoperative morbidity and mortality rates. Specimen quality is similar after either approach, for cancers located at the right and left colon, but not at the transverse colon.

CONCLUSION

There is strong evidence that CME offers a longer central pedicle that contains more lymph nodes than conventional surgery for colon cancer. CME represents the surgical background for the maximum lymph node harvest, an important quality marker for the surgical outcome. However, and according to present data, there is limited evidence that colectomy in terms of CME leads to improved long-term oncological outcomes.

Complete mesocolic excision: Lessons from anatomy translating to better oncologic outcome

Since the introduction of complete mesocolic excision (CME) for colon cancer, the oncologic outcome of patients has been greatly improved, which has led to a longer survival and a lower recurrence, just like the total mesorectum excision for rectal cancer. Despite the fact that the exact anatomy of the organ is one of the most vital things for surgeons to conduct surgery, no team has really studied the exact structure of the mesocolon and related attachments for CME, until the mesocolonic anatomy was first formally characterized in 2012. Therefore, this article mainly focuses on the anatomy development of the mesocolon and the achievement in this field. Meanwhile, we introduce the latest progress in laparoscopic surgery for colon cancer achieved by our team.

Laparoscopic complete mesocolic excision with central vascular ligation in right colon cancer: A comprehensive review

Aim of the study is to comprehensively review the latest trends in laparoscopic complete mesocolic excision (CME) with central vascular ligation (CVL) for the multimodal management of right colon cancer. Historical and up-to-date anatomo-embryological concepts are analyzed in detail, focusing on the latest studies of the mesenteric organ, its dissection by mesofascial and retrofascial cleavage planes, and questioning the need for a new terminology in colonic resections. The rationale behind Laparoscopic CME with CVL is thoroughly investigated and explained. Attention is paid to the current surgical techniques and the quality of the surgical specimen, yielded through mesocolic, intramesocolic and muscularis propria plane of surgery. We evaluate the impact on long term oncologic outcome in terms of local recurrence, overall and disease-free survival, according to the plane of resection achieved. Conclusions are drawn on the basis of the available evidence, which suggests a pivotal role of laparoscopic CME with CVL in the multimodal management of right sided colonic cancer: performed in the right mesocolic plane of resection, laparoscopic CME with CVL demonstrates better oncologic results when compared to standard non-mesocolic planes of surgery, with all the advantages of laparoscopic techniques, both in faster recovery and better immunological response. The importance of minimally invasive meso-resectional surgery is thus stressed and highlighted as the new frontier for a modern laparoscopic total right mesocolectomy.

Complete mesocolic excision in colorectal cancer: a systematic review

AIM

Several studies have suggested an increased lymph node yield, reduced locoregional recurrence and increased disease-free survival after complete mesocolic excision (CME) for colorectal cancer. This review was undertaken to assess the use of CME for colon cancer by evaluating the technique and its clinical outcome.

METHOD

A literature search of publications was performed using PubMed and Medline. Only studies published in English were included. Studies assessed for quality and data were extracted by two independent reviewers. End-points included number of lymph nodes per patient, quality of the plane of mesocolic excision, postoperative mortality and morbidity, 5-year locoregional recurrence and 5-year cancer-specific survival.

RESULTS

There were 34 articles comprising 12 retrospective studies, nine prospective studies and 13 original articles including case series, observational studies and editorials. Of the prospective studies, four reported an increased lymph node harvest and a survival benefit. The others reported an improvement in the quality of the specimen as assessed by histopathological examination. Laparoscopic CME has the same oncological outcome as open surgery but completeness of excision during laparoscopy may be compromised for tumours in the transverse colon.

CONCLUSION

Studies demonstrate that CME removes significantly more tissue around the tumour including maximal lymph node clearance. There is little information on serious adverse events after CME and a long-term survival benefit has not been proved.

A detailed appraisal of mesocolic lymphangiology--an immunohistochemical and stereological analysis

Inadequate resection of the adjoining mesentery is associated with adverse outcome for colon cancer. Disruption of the integrity of the mesenteric lymphatic package has been implicated in this, though not proven. Recent studies have determined mesenteric anatomy and histology and now provide an opportunity to determine accurately the distribution of lymphatic vessels. The aim of this study was to characterise the distribution of the lymphatic vessels (LV) within the small intestinal and colonic mesentery, and in Toldt's fascia, which lies between the mesocolon and underlying retroperitoneum. Mesenteric samples were harvested from 12 human cadavers. Samples were taken from the small bowel mesentery, ascending, transverse, descending mesocolon and from both apposed and non-apposed portions of the mesosigmoid. Serial sections were stained immunohistochemically with monoclonal antibody D2-40 (podoplanin), and Masson's Trichrome. Lymphatic vessel (LV) density and radius of diffusion were determined using a stereological approach. A lymphatic network was embedded within the mesenteric connective tissue lattice throughout each mesenteric region. LV were identifiable within the submesothelial connective tissue where they measured 10.2 ± 4.1 μm in diameter and had an average radius of diffusion of 174.72 ± 97.68 μm. Unexpectedly, LV were identified in Toldt's fascia, where they measured 4.3 ± 3.1 μm in diameter and had a radius of diffusion of 165.12 ± 66.26 μm. This is the first study systematically to determine and quantify the distribution of lymphatic vessels within the mesenteric organ and to demonstrate the presence of such vessels within Toldt's fascia. A rich lymphatic network occupies all levels of the mesenteric connective tissue lattice. Within the latter, they are found within 0.1 mm of peritonealised mesenteric surfaces and are separated by an average distance of 0.17 mm and may be particularly vulnerable during surgery.