Pattern of Colon Cancer Lymph Node Metastases in Patients Undergoing Central Mesocolic Lymph Node Excision: A Systematic Review

Innovative pancreas-guided technique for splenic flexure mobilization in laparoscopic left hemicolectomy

OBJECTIVE

Splenic flexure mobilization (SFM) is a major challenge in laparoscopic left hemicolectomy. This study aims to assess the safety and effectiveness of the pancreas-guided SFM technique during laparoscopic left hemicolectomy.

METHODS

From January 2018 to December 2023, 352 patients with left-sided colon cancer underwent laparoscopic left hemicolectomy. Based on the SFM method used, the patients were divided into the pancreas-guided group (167 cases) or the "Three Approaches Roundabout"/classic group (185 cases). Clinicopathologic characteristics and intraoperative and postoperative variables were compared between the two groups.

RESULTS

The two groups had no significant differences in baseline indicators (P > 0.05). All surgeries were successful without needing to convert to laparotomy, and there were no combined organ resections involving the spleen or pancreas in either group. The mean duration of surgery was significantly lower in the pancreas-guided group than in the classic group (P < 0.01). The median volume of intraoperative blood loss in the pancreas-guided group was lower than that in the classic group (P < 0.01). Through video playback, it was found that the retro-pancreatic space had been entered during operation in 8 cases (4.3%) in the classic group, while there were no such occurrences in the pancreas-guided group. This difference was statistically significant (P < 0.05). The difference in the number of lymph nodes cleared, postoperative hospital stays, and incidence of complications were not statistically significant (all P > 0.05) between the groups.

CONCLUSION

The pancreas-guided SFM technique is a safe and feasible option for laparoscopic left hemicolectomy. Our study's findings suggest that this approach facilitates accurate access to the correct anatomic plane, potentially improving surgical efficiency.

Survival analysis in pT1-3 and paracolic lymph-node invasion colorectal cancer: the prognostic role of positive paracolic lymph-node ratio for adjuvant chemotherapy

PURPOSE

Several studies have observed that some stage III colorectal cancer (CRC) patients cannot benefit from standard adjuvant chemotherapy. However, there is no unified screening standard to date.

METHODS

Consecutive patients with pathologically confirmed colon adenocarcinoma treated in 3 centers between January 2016 and December 2018 were included. Patients were divided into four groups according to different stages and positive paracolic lymph-node ratio (P-LNR) [Cohort 1: pT1-3N0M0, Cohort 2: pT1-3N + (P-LNR ≤ 0.15)M0, Cohort 3: pT4N0M0, Cohort 4: stage III patients except for pT1-3N + (P-LNR ≤ 0.15)M0], and further overall survival was compared by Kaplan-Meier method. The univariate and multivariate analyses were employed for cox proportional hazards model.

RESULTS

We retrospectively reviewed 5581 consecutive CRC patients with, and 2861 eligible patients were enrolled for further analysis. The optimal cut-off value of P-LNR in our study was 0.15. There was no significant difference in OS (91.36 vs. 93.74%) and DFS (87.65 vs. 90.96%) between stage III patients with pT1-3N + (P-LNR ≤ 0.15)M0 and those with pT1-3N0M0. Further analysis demonstrated that CRC patients with pT1-3N + (P-LNR ≤ 0.15)M0 were less likely to benefit from 8 cycles of CAPOX or FOLFOX chemotherapy and suffered fewer adverse events from declining chemotherapy. Comparing with 0-4 cycles versus 8 cycles, the overall survival rates were 91.35 versus 90.19% (P = 0.79), and with a DFS of 87.50 versus 88.24% (P = 0.49), the duration of adjuvant chemotherapy was not an independent risk factor for patients with pT1-3N + (P-LNR ≤ 0.15)M0 (HR: 0.70, 95% CI 0.90-1.30, P = 0.42).

CONCLUSION

The concept of P-LNR we proposed might have a high clinical application value and accurately enable clinicians to screen out specific CRC patients who decline or prefer limited chemotherapy.

TRIAL REGISTRY

The clinical trial registration number: ChiCTR2300076883.

Lymphatic spread patterns in young versus elderly patients with stage III colon cancer

BACKGROUND

The anatomical pattern of lymph nodes spread differs between young (aged 45 years or younger) and elderly (aged 80 years or older) patients with stage III colon cancer and is poorly investigated.

METHODS

Two groups of patients (young and elderly) with stage III colon cancer who underwent upfront extensive (D3) lymphadenectomy at eight Japanese centres between 1998 and 2018 were retrospectively analysed. The primary endpoint was the proportion of positive central lymph nodes. The lymph nodes spreading pattern and its prognostic impact on recurrence-free survival and overall survival in the two groups were also compared.

RESULTS

Two hundred and ten young patients and 348 elderly patients were identified and compared. The total number of lymph nodes harvested and the total number of invaded lymph nodes were significantly higher in younger patients compared with elderly patients (median of 31.5 (3-151) versus 21 (3-116), P < 0.001 and median of 3 (1-21) versus 2 (1-25), P < 0.001 respectively). The proportion of positive central lymph nodes were higher in younger patients than in elderly patients (9.52% (95% c.i. 6.24 to 14.2%) versus 4.59% (95% c.i. 2.84 to 7.31%), P = 0.012). In multivariate models for recurrence-free survival, central lymph nodes invasion were identified as a poor prognostic factor in younger patients (HR 5.21 (95% c.i. 1.76 to 15.39)) but not in elderly patients (HR 1.73 (95% c.i. 0.80 to 3.76)).

CONCLUSION

Young patients with stage III colon cancer have a higher risk of central lymph nodes invasion, suggesting a more aggressive disease biology. The presence of central lymph nodes invasion are associated with a worse outcome in young patients.

Complete mesocolic excision and extended lymphadenectomy: Where should we stand?

Debate regarding the risks and merits of complete mesocolic excision and extended lymphadenectomy is ongoing, particularly for right-sided colon cancers. In this article, we hope to provide a succinct yet encompassing review of the relevant literature. We posit that complete mesocolic excision with D3 dissection is indicated in select patients with colon cancers, particularly those distal to the cecum.

Deep learning to predict lymph node status on pre-operative staging CT in patients with colon cancer

INTRODUCTION

Lymph node (LN) metastases are an important determinant of survival in patients with colon cancer, but remain difficult to accurately diagnose on preoperative imaging. This study aimed to develop and evaluate a deep learning model to predict LN status on preoperative staging CT.

METHODS

In this ambispective diagnostic study, a deep learning model using a ResNet-50 framework was developed to predict LN status based on preoperative staging CT. Patients with a preoperative staging abdominopelvic CT who underwent surgical resection for colon cancer were enrolled. Data were retrospectively collected from February 2007 to October 2019 and randomly separated into training, validation, and testing cohort 1. To prospectively test the deep learning model, data for testing cohort 2 was collected from October 2019 to July 2021. Diagnostic performance measures were assessed by the AUROC.

RESULTS

A total of 1,201 patients (median [range] age, 72 [28-98 years]; 653 [54.4%] male) fulfilled the eligibility criteria and were included in the training (n = 401), validation (n = 100), testing cohort 1 (n = 500) and testing cohort 2 (n = 200). The deep learning model achieved an AUROC of 0.619 (95% CI 0.507-0.731) in the validation cohort. In testing cohort 1 and testing cohort 2, the AUROC was 0.542 (95% CI 0.489-0.595) and 0.486 (95% CI 0.403-0.568), respectively.

CONCLUSION

A deep learning model based on a ResNet-50 framework does not predict LN status on preoperative staging CT in patients with colon cancer.

Prognostic value of lymph node distribution after laparoscopic colectomy with Japanese D3 dissection

PURPOSE

Positive pathologic lymph nodes in colorectal cancer represent an important prognostic indicator. Whether lymph node distribution or the number of metastatic nodes is more strongly associated with survival prediction remains controversial.

METHODS

Among 3449 colorectal cancer surgeries performed at Nagasaki University Hospital and five affiliated institutions from April 2016 to March 2022, we investigated 604 patients who underwent laparoscopic radical resection and were diagnosed with pathological stage III cancer. Patients were divided into two groups according to whether they had central vessel metastasis (LND3 group, n=42) or not (LND1/2 group, n=562). After adjusting for background factors using propensity score matching, the LND3 group included 42 patients and the LND1/2 group included 40 patients. Patient background characteristics and prognosis were compared between these two groups.

RESULTS

Before matching, frequencies of right-side colon cancer (64.3% vs 38.1%, p=0.001), multivisceral resection (11.9% vs 4.4%, p=0.039), clinical N2 status (40.5% vs 22.6%, p=0.032), and pathological N2 (73.8% vs 22.6%, p<0.001) were all greater, and the number of lymph nodes retrieved was higher (24 vs 19, p=0.042) in the LND3 group. After matching, no differences in any clinical factors were evident between groups. Five-year RFS (44.8% vs 77.1%, p=0.004) and OS (43.1% vs 83.2%, p<0.001) were worse in the LND3 group. Adjuvant chemotherapy improved RFS (adjuvant chemotherapy (+) vs adjuvant chemotherapy (-): 62.1% vs 27.7%, p=0.047) in the LND3 group.

CONCLUSION

LND3-positive patients show poorer prognosis than LND1/2 patients and should be treated with an appropriate perioperative treatment strategy.

Complete mesocolic excision for right colon cancer: Is D3 lymphadenectomy necessary?

AIM

Although complete mesocolic excision (CME) for colon cancer is oncologically sound, to date, there has been no consensus on the extent of lymphadenectomy in radical right colectomy. This study essentially compared the perioperative and survival outcomes of CME with two templates of lymphadenectomy for right colon cancer.

METHOD

This was a propensity matched, retrospective analysis of a single centre, prospectively maintained database of all patients undergoing elective right colectomy for nonmetastatic, biopsy-proven adenocarcinoma from November 2013 to October 2018. CME + D3 was adopted selectively, documented prospectively, and compared with patients undergoing CME + central vascular ligation (CVL). The only technical difference between the groups was the excision of the surgical trunk of Gillot in the CME + D3 group. Postoperative, long-term outcomes and patterns of recurrence were compared between the groups.

RESULTS

Of the 244 eligible patients, 88 (36.1%) and 156 (63.9%) underwent CME + D3 and CME + CVL, respectively. Matched groups (72 [CME + D3] vs. 108 [CME + CVL]) showed no difference in histology, tumour grade, postoperative complications, mortality, and hospital stay. CME + D3 was preferentially performed laparoscopically (35.2% vs. 9%), was associated with lower blood loss (215 mL vs. 297 mL, p = 0.001), higher nodal yield (31 vs. 25 nodes, p = 0.003) and a higher incidence of chyle leak (4 vs. 0, p = 0.013). At a median follow-up of more than 57 months, there was no significant difference in local recurrence, disease-free or overall survival.

CONCLUSION

In this retrospective study, lymphadenectomy along the superior mesenteric vein, as a component of CME for right colon cancer, offered a higher nodal yield with no improvement in oncological outcome. Dissection of the SMV, over and above a D2 dissection, could therefore be restricted to specialized colorectal units until further studies establish the incremental oncological benefit of this extended lymphadenectomy or define a patient group in whom it is beneficial.

Clinical Effectiveness of Fluorescence Lymph Node Mapping Using ICG for Laparoscopic Right Hemicolectomy: A Prospective Case-Control Study

BACKGROUND

The distinction between D3 lymph nodes and actual lymphatic pathways in primary tumors can be difficult during surgery, making it challenging to confirm the completeness of D3 lymph node dissection. Fluorescence lymph node mapping (FLNM) is a promising method for lymph node visualization.

PURPOSE

This study aimed to assess whether FLNM enhances the effectiveness of D3 lymph node dissection in patients with right-sided colon cancer.

METHODS

Endoscopic submucosal indocyanine green injection were performed on the distal margin of the colon cancer. In an FLNM group, the lymphatic drainage pathway and distribution of D3 lymph nodes were explored. Pathological evaluations were conducted for the fluorescent D3 and non-fluorescent D3 lymph nodes.

RESULTS

The FLNM group showed a significantly higher number of harvested lymph nodes in the D3 area. In stage III patients, the proportion of D3 lymph node metastasis was significantly higher in the FLNM group. The harvested D3 lymph node count showed a proportional correlation with a metastatic lymph node count of up to 15.

CONCLUSION

FLNM could be considered a promising new strategy to potentially increase harvested D3 lymph node counts in colon cancer surgery.

Validation of the German classification system for quality assessment of right-sided colon cancer specimens

AIM

The German classification system of the completeness of mesocolic excision aims to assess the quality of right-sided colonic cancer surgery by review of photographs. We aimed to validate the reliability of the classification in a clinical context.

METHOD

The study was based on a cohort of patients undergoing resection for right-sided colon cancer in two university hospitals served by the same group of pathologists. Prospectively collected photographs of the specimens were assessed twice by six colorectal surgeons to determine the intra-rater and inter-rater accuracy of the German classification and a modification assessing extended right-sided resections.

RESULTS

Specimens from 613 resections for right-sided colon cancer were reviewed. Twenty-one specimens were found to be non-assessable, leaving 436 right hemicolectomies, 139 extended right hemicolectomies and 17 right-sided subtotal colectomies. Intra-rater reliability was 0.57-0.74 and weighted kappa coefficients 0.58-0.74, without differences between subgroups. The percentage of agreement between all six participants was 20.3% for all specimens, 21.1% for right hemicolectomy specimens and 18.1% for extended hemicolectomy and right-sided subtotal colectomy specimens. For the right hemicolectomy specimens, the model-based kappa coefficient for agreement was 0.27 (95% CI 0.24-0.30) and for association 0.45 (95% CI 0.41-0.49).

CONCLUSION

The German classification of right hemicolectomy specimens showed low intra-rater reliability and inter-rater agreement and association. The use of this classification for scientific purposes appeared not to be reliable.

Association between plane of mesocolic dissection and recurrence after complete mesocolic excision for right-sided colon cancer: a cohort study

AIM

Dissection in the mesocolic plane is considered by some medical professionals to be crucial in complete mesocolic excision. We aimed to assess whether intramesocolic plane dissection is associated with a risk of recurrence after complete mesocolic excision for right-sided colon cancer.

METHOD

This is a single-centre study based on prospectively registered data on patients undergoing resection for Union for International Cancer Control Stage I-III right-sided colon adenocarcinoma during the period 2010-2017. Patients were stratified in an intramesocolic plane group or a mesocolic plane group based on a prospective assessment of fresh specimens by a pathologist. Primary outcome was the 4.2 year risk of recurrence after inverse probability treatment weighting and competing risk analyses.

RESULTS

Of 383 patients, 4 (1%) were excluded as the specimen was assessed as muscularis propria plane, 347 (91.6%) specimens were deemed as mesocolic and 32 (8.4%) as intramesocolic. The 4.2 year cumulative incidence of recurrence after inverse probability treatment weighting was 9.1% (95% CI 6.0%-12.1%) in the mesocolic group compared with 14.0% (3.6%-24.5%) in the intramesocolic group with an absolute risk difference in favour of mesocolic plane dissection of 4.9% (-5.7 to 15.6, p = 0.37). No difference was observed in the risk of local recurrence, death before recurrence or overall survival after 4.2 years between the two groups.

CONCLUSION

Mesocolic plane dissection can be achieved in more than 90% of patients. The classification seems to be a guide for good surgical practice and not to be used for research purposes.

Robotic versus laparoscopic right hemicolectomy with complete mesocolic excision: a retrospective multicenter study with propensity score matching

Objective

During the past decade, the concept of complete mesocolic excision (CME) has been developed in an attempt to minimize recurrence for right-sided colon cancer. This study aims to compare outcomes of robotic versus laparoscopic right hemicolectomy with CME for right-sided colon cancer.

Methods

We performed a retrospective multicenter propensity score matching study. From July 2016 to July 2021, 382 consecutive patients from different Chinese surgical departments were available for inclusion out of an initial cohort of 412, who underwent robotic or laparoscopic right hemicolectomy with CME. Data of all patients were retrospectively collected and reviewed. Of these, 149 cases were performed by a robotic approach, while the other 233 cases were done by laparoscopy. Propensity score matching was applied at a ratio of 1:1 to compare perioperative, pathologic, and oncologic outcomes between the robotic and the laparoscopic groups (n = 142).

Results

Before propensity score matching, there were no statistical differences regarding the sex, history of abdominal surgery, body mass index (BMI), American Joint Committee on Cancer (AJCC) staging system, tumor location, and center between groups (p > 0.05), while a significant difference was observed regarding age (p = 0.029). After matching, two comparable groups of 142 cases were obtained with equivalent patient characteristics (p > 0.05). Blood loss, time to oral intake, return of bowel function, length of stay, and complications were not different between groups (p > 0.05). The robotic group showed a significantly lower conversion rate (0% vs. 4.2%, p = 0.03), but a longer operative time (200.9 min vs. 182.3 min, p < 0.001) and a higher total hospital cost (85,016 RMB vs. 58,266 RMB, p < 0.001) compared with the laparoscopic group. The number of harvested lymph nodes was comparable (20.4 vs. 20.5, p = 0.861). Incidence of complications, mortality, and pathologic outcomes were similar between groups (p > 0.05). The 2-year disease-free survival rates were 84.9% and 87.1% (p = 0.679), and the overall survival rates between groups were 83.8% and 80.7% (p = 0.943).

Conclusion

Despite the limitations of a retrospective analysis, the outcomes of robotic right hemicolectomy with CME were comparable to the laparoscopic procedures with fewer conversions to open surgery. More clinical advantages of the robotic surgery system need to be further confirmed by well-conducted randomized clinical trials with large cohorts of patients.

Simultaneous, Multi-Channel, Near-Infrared Fluorescence Visualization of Mesenteric Lymph Nodes Using Indocyanine Green and Methylene Blue: A Demonstration in a Porcine Model

Near-infrared fluorescence (NIRF) image-guided surgery is a useful tool that can help reduce perioperative complications and improve tissue recognition. Indocyanine green (ICG) dye is the most frequently used in clinical studies. ICG NIRF imaging has been used for lymph node identification. However, there are still many challenges in lymph node identification by ICG. There is increasing evidence that methylene blue (MB), another clinically applicable fluorescent dye, can also be useful in the intraoperative fluorescence-guided identification of structures and tissues. We hypothesized that MB NIRF imaging could be used for lymph node identification. The aim of this study was to evaluate the feasibility of intraoperative lymph node fluorescence detection using intravenously (IV) administered MB and compare it to ICG via a camera that has two dedicated near-infrared (NIR) channels. Three pigs were used in this study. ICG (0.2 mg/kg) was administered via a peripheral venous catheter followed by immediate administration of MB (0.25 mg/kg). NIRF images were acquired as video recordings at different time points (every 10 min) over an hour using the QUEST SPECTRUM^® 3 system (Quest Medical Imaging, Middenmeer, The Netherlands), which has two dedicated NIR channels for simultaneous intraoperative fluorescence guidance. The 800 nm channel was used to capture ICG fluorescence and the 700 nm channel was used for MB. The target (lymph nodes and small bowel) and the background (vessels-free field of the mesentery) were highlighted as the regions of interest (ROIs), and corresponding fluorescence intensities (FI) from these ROIs were measured. The target-to-background ratio (TBR) was then computed as the mean FI of the target minus the mean FI of the background divided by the mean FI of the background. In all included animals, a clear identification of lymph nodes was achieved at all time points. The mean TBR of ICG in lymph nodes and small bowel was 4.57 ± 1.00 and 4.37 ± 1.70, respectively for the overall experimental time. Regarding MB, the mean TBR in lymph nodes and small bowel was 4.60 ± 0.92 and 3.27 ± 0.62, respectively. The Mann-Whitney U test of the lymph node TBR/small bowel TBR showed that the TBR ratio of MB was statistically significantly higher than ICG. The fluorescence optical imaging technology used allows for double-wavelength assessment. This feasibility study proves that lymph nodes can be discriminated using two different fluorophores (MB and ICG) with different wavelengths. The results suggest that MB has a promising potential to be used to detect lymphatic tissue during image-guided surgery. Further preclinical trials are needed before clinical translation.

Infrapyloric (No. 206) and greater curvature (No. 204) lymph node metastasis in adenocarcinoma located in the right half of the transverse colon (InCLART Study): protocol for a multicentre prospective observational study

INTRODUCTION

In the case of right-sided transverse colon cancer (RTCC) and hepatic flexure colon cancer (HFCC), there is a potential connection of lymph drainage between mesentery and greater omentum. However, most previous reports have been limited case series with No. 206 and No. 204 lymph node (LN) dissection for RTCC and HFCC.

METHODS AND ANALYSIS

The InCLART Study is a prospective observational study aiming to enrol 427 patients with RTCC and HFCC treated at 21 high-volume institutions in China. The prevalence of infrapyloric (No. 206) and greater curvature (No. 204) LN metastasis and short-term outcomes will be investigated in a consecutive series of patients with T2 or deeper invasion RTCC or HFCC, following the principle of complete mesocolic excision with central vascular ligation. Primary endpoints were performed to identify the prevalence of No. 206 and No. 204 LN metastasis. Secondary analyses will be used to estimate prognostic outcomes, intraoperative and postoperative complications, the consistency of preoperative evaluation and postoperative pathological results of LN metastasis.

ETHICS AND DISSEMINATION

Ethical approval for the study has been granted by the Ruijin Hospital Ethics Committee (approval number: 2019-081) and has been or will be approved successively by each participating centre's Research Ethics Board. The findings will be disseminated in peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT03936530; https://clinicaltrials.gov/ct2/show/NCT03936530).

The mesocolic apical fragment in complete mesocolic excision colectomies: Should it be analysed separately? A proof-of-concept study

AIM

The aim of this work is to describe a protocol and assess the feasibility of harvesting and analysing the mesocolic apical fragment (MAF) for the presence of central lymph node (LN) metastasis and extra lymphatic free tumour cells in a random subgroup extracted from a cohort of complete mesocolic excision colectomies with central vascular ligation.

METHOD

Forty-seven patients diagnosed with colorectal cancer were included. A 2/2 cm pyramid of tissue was cut around the central tie and sent for pathological examination. The MAF was sectioned into 16 slices. High-definition images were taken from the slices which were merged into a panoramic three-dimensional image of the MAF. The distribution of LNs in the MAF was quantified. Immunohistochemistry staining for cytokeratin 14 was used to identify isolated tumour cells and micrometastases in the extranodal tissue.

RESULTS

No tumoural cells migrating through the apical zone, outside of the LNs, were identified. Margins of resection, mesocolic tissue and LNs were all negative in the subgroup of ultrastaged MAFs. The number of examined central LNs varied between 0 and 24, with positive MAF LNs being identified only in pN2 stages. The rate of positive apical LNs in our cohort was 4.2% (n = 2).

CONCLUSIONS

The MAF can be easily extracted from standard specimens, allowing for accurate analysis of lymphatic and extra-nodal tumour cells on the central resection margins, in central LNs and in the apical mesocolic tissue. Future research on larger cohorts is required to establish if analysing the MAF has an impact on patient staging, prognosis and management.

A Clinicopathological Feature-Based Nomogram for Predicting the Likelihood of D3 Lymph Node Metastasis in Right-Sided Colon Cancer Patients

BACKGROUND

Despite advancements in treating right-sided colon cancer patients, the ideal scope of lymphadenectomy remains controversial.

OBJECTIVE

Our objective was to investigate the likelihood of D3 lymph node metastasis in right-sided colon cancer patients and develop a clinicopathological feature-based nomogram for D3 lymphadenectomy.

DESIGN

We retrospectively analyzed 286 right-sided colon cancer patients who underwent D3 lymphadenectomy. The patients were divided into 2 groups based on whether D3 lymph node metastasis was positive. Then, univariable and multivariable logistic regression analyses were performed to obtain independent risk factors for predicting D3 lymph node metastasis. Moreover, we performed receiver operating characteristic curve analyses to evaluate the predictive power of the model.

SETTING

This study was conducted at Nanfang Hospital of Southern Medical University in China.

PATIENTS

A total of 286 consecutive patients who underwent right hemicolectomy and D3 lymphadenectomy as a primary treatment for right-sided colon cancer between January 2016 and December 2019 were enrolled in this study.

MAIN OUTCOME MEASURES

The primary measures were independent risk factors for predicting D3 lymph node metastasis in right-sided colon cancer.

RESULTS

The D3 lymph node metastasis rate in right-sided colon cancer patients was 16.1% (46/286). D3 lymphadenectasis on CT, lymphatic invasion, and T4 tumors were filtered out as independent risk factors for D3 lymph node metastasis according to the multivariable logistic regression analysis. We established a nomogram that predicted D3 lymph node metastasis of right-sided colon cancer on the combination of the 3 factors with an area under the curve of 0.717 (95% CI, 0.629-0.806).

LIMITATIONS

This was a retrospective study from a single center.

CONCLUSIONS

We developed a valuable clinicopathological feature-based nomogram to predict the incidence of D3 lymph node metastasis in right-sided colon cancer patients. Patients with D3 lymphadenectasis on CT, preoperative T4 tumors, and lymphatic invasion should undergo D3 lymphadenectomy. See Video Abstract at http://links.lww.com/DCR/B852 .

UN NOMOGRAMA BASADO EN CARACTERSTICAS CLNICOPATOLGICAS PARA PREDECIR LA PROBABILIDAD DE METSTASIS EN GANGLIOS LINFTICOS D EN PACIENTES CON CNCER DE COLON DERECHO

ANTECEDENTES:A pesar de los avances en el tratamiento de pacientes con cáncer de colon derecho, el ámbito ideal de la linfadenectomía sigue siendo controvertido.OBJETIVO:Investigar la probabilidad de metástasis en los ganglios linfáticos D3 en pacientes con cáncer de colon derecho y desarrollar un nomograma basado en características clínico-patológicas basado para la linfadenectomía D3.DISEÑO:Analizamos retrospectivamente a 286 pacientes con cáncer de colon derecho que se sometieron a linfadenectomía D3. Los pacientes se dividieron en dos grupos en función de si eran positivos para metástasis en los ganglios linfáticos D3. Luego, se realizaron análisis de regresión logística univariable y multivariable para obtener factores de riesgo independientes para predecir metástasis en los ganglios linfáticos D3. Además, realizamos análisis de las curvas de características operatorias del receptor para evaluar el poder predictivo del modelo.SEDE:Este estudio se realizó en el Hospital Nanfang de la Universidad Médica del Sur en China.PACIENTES:Un total de 286 pacientes consecutivos que se sometieron a hemicolectomía derecha y linfadenectomía D3 como tratamiento primario para el cáncer de colon derecho entre enero de 2016 y diciembre de 2019 se inscribieron en este estudio.PRINCIPALES MEDIDAS DE RESULTADO:Las medidas primarias fueron factores de riesgo independientes para predecir las metástasis en ganglios linfáticos D3 en el cáncer de colon derecho.RESULTADOS:La tasa de metástasis en los ganglios linfáticos D3 en pacientes con cáncer de colon del lado derecho fue del 16,1% (46/286). El aumento de tamaño de ganglios D3 en la TC, la invasión linfática y los tumores T4 se filtraron como factores de riesgo independientes de metástasis en los ganglios linfáticos D3 de acuerdo con el análisis de regresión logística multivariable. Establecimos un nomograma que predijo metástasis en los ganglios linfáticos D3 del cáncer de colon derecho en la combinación de los tres factores con un área bajo la curva de 0,717 (IC del 95%, 0,629-0,806).LIMITACIONES:Este fue un estudio retrospectivo de un solo centro.CONCLUSIONES:Desarrollamos un valioso nomograma basado en características clínico-patológicas para predecir la incidencia de metástasis en los ganglios linfáticos D3 en pacientes con cáncer de colon derecho. Los pacientes con crecimiento de ganglios D3 en TC, tumores con clasificación preoperatoria T4 e invasión linfática, deben ser sometidos a linfadenectomía D3. Consulte Video Resumen en http://links.lww.com/DCR/B852 . (Traducción-Dr. Juan Carlos Reyes ).

Mid-term oncological outcomes after complete versus conventional mesocolic excision for right-sided colon cancer: a propensity score matching analysis

BACKGROUND

The correct extent of mesocolic dissection for right-sided colon cancer (RCC) is still under debate. Complete mesocolic excision (CME) has not gained wide diffusion, mainly due to its technical complexity and unclear oncological superiority. This study aims to evaluate oncological outcomes of CME compared with non-complete mesocolic excision (NCME) during resection for I-III stage RCC.

METHOD

Prospectively collected data of patients who underwent surgery between 2010 and 2018 were retrospectively analysed. 1:1 Propensity score matching (PSM) was used to balance baseline characteristics of CME and NCME patients. The primary endpoint of the study was local recurrence-free survival (LRFS). The two groups were also compared in terms of short-term outcomes, distant recurrence-free survival, disease-free survival, and overall survival.

RESULTS

Of the 444 patients included in the study, 292 were correctly matched after PSM, 146 in each group. The median follow-up was 45 months (IQR 33-63). Conversion rate, complications, and 90-day mortality were comparable in both groups. The median number of lymph nodes harvested was higher in CME patients (23 vs 19, p = 0.034). 3-year LRFS rates for CME patients was 100% and 95.6% for NCME (log-rank p = 0.028). At 3 years, there were no differences between the groups in terms of overall survival, distant recurrence-free survival, and disease-free survival.

CONCLUSION

Our PSM cohort study shows that CME is safe, provides a higher number of lymph nodes harvested, and is associated with better local recurrence-free survival.

Risk factors of central area lymph nodes metastasis for guiding optimal right colon cancer surgery: A retrospective multicenter study.. [DOI: 10.21203/rs.3.rs-1991182/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: D3 or CME lymphadenectomy for right colon cancer (RCC) with lymph nodes metastasis (LNM) is strongly recommended but the anatomical landmark remains controversial. Central LNM predicted poor prognosis in RCC and determined the extent of lymphadenectomy. Methods: Data for 1712 RCC patients treated with D3/CME lymphadenectomy were reviewed. These patients had been treated in 9 centers. A total of 1023 RCC patients were enrolled in the derivation cohort while 689 patients were enrolled in the validation cohort. Results: The overall central LNM incidence was 12.58% (215/1712). In the derivation cohort, univariate and multivariate cox regression analyses revealed that preoperative N staging based on CT scan (OR=7.85, 95% CI, 4.53-14.51, p<0.001), tumor differentiation (OR=0.53, 95% CI, 0.33-0.86, p=0.01) and intraoperative view of tumor movability (OR=0.53, 95% CI, 0.33-0.86, p=0.02) were significant independent factors. Areas under receiver-operating characteristic curves (AUC) for assessing central LNM in the derivation and validation cohorts were 0.802 and 0.750, respectively. The risk-scoring system for patients with RCC was also established. A score of 0 points was the optimal cut-off value for central LNM. Compared to patients in the low-risk group, patients in the high-risk group exhibited worse overall survival outcomes (p<0.001).Conclusions: The established model can be used for preoperative assessment of the risk of central LNM in RCC patients, and for determining the landmark for D3/CME lymphadenectomy, therefore might contribute to decreased therapeutic complications and improved clinical outcomes.

Plane of mesocolic dissection as predictor of recurrence after complete mesocolic excision for sigmoid colon cancer: A cohort study

AIM

To investigate whether intramesocolic plane dissection assessed on fresh specimens by the pathologist is a risk factor for recurrence after complete mesocolic excision for sigmoid cancer when compared with mesocolic plane dissection.

METHOD

Single-centre study based on prospectively registered data on patients undergoing resection for UICC stage I-III sigmoid colon adenocarcinoma during the period 2010-2017. The patients were stratified into either an intramesocolic plane group or a mesocolic plane group. Primary outcome was risk of recurrence after 4.2 years using inverse probability treatment weighting and competing risk analyses.

RESULTS

Of a total of 332 patients, two were excluded as the specimen was assessed as muscularis propria plane, 237 (72%) specimens were deemed as mesocolic and 93 (28%) as intramesocolic. The 4.2-year cumulative incidence of recurrence after inverse probability treatment weighting was 14.9% (10.4-19.3) in the mesocolic group compared with 9.4% (3.7-15.0) in the intramesocolic group, thus the absolute risk difference between the mesocolic plane and intramesocolic plane was 5.5% (-12.5-1.6; p = 0.13) in favour of the intramesocolic group.

CONCLUSION

Intramesocolic plane dissection was not a risk factor for recurrence after complete mesocolic excision for sigmoid cancer when compared with mesocolic plane dissection. No difference in risk of local recurrence, death before recurrence, and in overall survival after 4.2 years was observed between the two groups. With less than 1% of the specimens deemed as muscularis propria plane dissection, the classification appears unusable for the risk prediction of sigmoid colon cancer.

Multidimensional evaluation of the learning curve for laparoscopic complete mesocolic excision for right colon cancer: a risk-adjusted cumulative summation analysis

AIM

Despite the suggested potential benefit of complete mesocolic excision (CME) for right-sided colon cancer (RCC) for patient survival, concerns about its safety and feasibility have contributed to delayed acceptance of the procedure, especially when performed by a minimally invasive approach. Thus, the aim of this work was to evaluate the actual learning curve (LC) of laparoscopic CME for experienced colorectal surgeons.

METHOD

Prospectively collected data for consecutive patients undergoing laparoscopic CME for RCC between October 2015 and January 2021 at our institution, operated on by experienced surgeons, were analysed. A multidimensional assessment of the LC was performed through cumulative sum (CUSUM) and risk-adjusted (RA) CUSUM analysis.

RESULTS

Two hundred and two patients operated by on by three surgeons were considered. The CUSUM graphs based on operating time showed one peak of the curve between 17 and 27 cases. The CUSUM graphs based on surgical failure showed one peak of the curve between 20 and 24 cases The RA-CUSUM curve also showed one preeminent peak at 24-33 cases. Based on the CUSUM and RA-CUSUM analyses all the surgeons reached proficiency in 24-33 cases.

CONCLUSIONS

Our study showed that an experienced minimally invasive colorectal surgeon acquires proficiency in laparoscopic CME for RCC after performing 24-33 cases.

Lymph Node Mapping in Transverse Colon Cancer Treated Using Laparoscopic Colectomy With D3 Lymph Node Dissection

BACKGROUND

Laparoscopic surgery for transverse colon cancer has been excluded from 7 randomized trials for various reasons. The optimal procedure for transverse colon cancer remains controversial.

OBJECTIVE

This study aimed to analyze the patterns of lymph node metastasis in transverse colon cancer and to report short- and long-term outcomes of the treatment procedures.

DESIGN

This was a single-center retrospective study.

SETTINGS

This study was conducted at Cancer Institute Hospital, Tokyo, Japan.

PATIENTS

We enrolled 252 patients who underwent laparoscopic surgery for transverse colon cancer.

INTERVENTIONS

The transverse colon was divided into 3 segments, and the procedures for transverse colon cancer were based on these segments, as follows: right hemicolectomy, transverse colectomy, and left hemicolectomy.

MAIN OUTCOME MEASURES

Postoperatively, the surgeons identified and mapped the lymph nodes from specimens and performed formalin fixation separately to compare the results of the pathological findings.

RESULTS

For right-sided, middle-segment, and left-sided transverse colon cancers, the frequency of lymph node metastases was 28.2%, 19.2%, and 19.2%. Skipped lymph node metastasis occurred in right-sided and left-sided transverse colon cancers but not in middle-segment transverse colon cancers. The pathological vascular invasion rate was significantly higher in right and left hemicolectomy than in transverse colectomy. For right hemicolectomy, transverse colectomy, and left hemicolectomy, 5-year overall survival rates were 96.3%, 92.7%, and 93.7%, and relapse-free survival rates were 92.4%, 88.3%, and 95.5%. In multivariate analysis, the independent risk factor for relapse-free survival was lymph node metastasis.

LIMITATIONS

Selection bias and different backgrounds may have influenced surgical and long-term outcomes.

CONCLUSION

Laparoscopic surgery for transverse colon cancer may be a feasible technique. Harvested lymph node mapping after laparoscopic resection based on D3 lymphadenectomy may help guide the field of dissection when managing patients who have transverse colon cancer. The only independent prognostic factor for relapse-free survival was node-positive cancer. See Video Abstract at http://links.lww.com/DCR/B706.MAPEO DE GANGLIOS LINFÁTICOS EN CÁNCER DE COLON TRANSVERSO TRATADO MEDIANTE COLECTOMÍA LAPAROSCÓPICA CON LINFADENECTOMÍA D3ANTECEDENTES:La cirugía laparoscópica en casos de cáncer de colon transverso fué excluida de siete estudios randomizados mayores por diversas razones. El procedimiento más idóneo en casos de cáncer de colon transverso, sigue siendo controvertido.OBJETIVO:Analizar los patrones de las metástasis en los ganglios linfáticos en casos de cáncer de colon transverso y reportar los resultados a corto y largo plazo de los diferentes procedimientos para su tratamiento.DISEÑO:Estudio retrospectivo en un solo centro de referencia.AJUSTE:Estudio llevado a cabo en el Hospital del Instituto del Cancer, Tokio, Japón.PACIENTES:Fueron incluidos 252 pacientes, sometidos a cirugía laparoscópica por cáncer de colon transverso.INTERVENCIONES:El colon transverso fué dividido en tres segmentos y los procedimientos en casos de cáncer se basaron sobre estos segmentos del tranverso, de la siguiente manera: hemicolectomía derecha, colectomía transversa y hemicolectomía izquierda.PRINCIPALES MEDIDAS DE RESULTADO:En el postoperatorio, los cirujanos identificaron y mapearon los ganglios linfáticos de las piezas quirúrgicas y las fijaron con formaldehido por separado para así poder comparar los resultados con los hallazgos histopatológicos.RESULTADOS:En los cánceres de colon transverso del segmento derecho, del segmento medio y del segmento izquierdo, la frecuencia de metástasis en los ganglios linfáticos fue del 28,2%, 19,2% y 19,2%, respectivamente. Las metástasis en los ganglios linfáticos omitidos se produjo en los cánceres de colon transverso del lado derecho y del lado izquierdo, pero no en los cánceres de colon transverso del segmento medio. La tasa de invasión vascular patológica fue significativamente mayor en la hemicolectomía derecha e izquierda que en la colectomía transversa. Para la hemicolectomía derecha, colectomía transversa y hemicolectomía izquierda, las tasas de supervivencia general a cinco años fueron del 96,3%, 92,7% y 93,7%, y las tasas de supervivencia sin recaída fueron del 92,4%, 88,3% y 95,5%, respectivamente. En el análisis multivariado, el factor de riesgo independiente para la sobrevida sin recidiva fue la metástasis en los ganglios linfáticos.LIMITACIONES:El sesgo de selección y los diferentes antecedentes pueden haber influido en los resultados quirúrgicos a largo plazo.CONCLUSIONES:La cirugía laparoscópica en casos de cáncer de colon transverso puede ser una técnica factible. El mapeo de los ganglios linfáticos recolectados después de la resección laparoscópica basada en la linfadenectomía D3 puede ayudar a guiar el campo de la disección en el manejo de pacientes con cáncer de colon transverso. El único factor pronóstico independiente para el SLR fue el cáncer con ganglios positivos. Consulte Video Resumen en http://links.lww.com/DCR/B706. (Traducción-Dr. Xavier Delgadillo).

ICG-Guided Lymphadenectomy during Surgery for Colon and Rectal Cancer-Interim Analysis of the GREENLIGHT Trial

Lymphadenectomy is crucial for an optimal oncologic resection of colon and rectal cancers. However, without a direct visualization, an aberrant route of lymph node (LN) diffusion might remain unresected. Indocyanine-green (ICG) lymphatic mapping permits a real-time LNs visualization. We designed the GREENLIGHT trial to explore in 100 patients undergoing robotic colorectal resection the clinical significance of a D3 ICG-guided lymphadenectomy. The primary endpoint was the number of patients in whom ICG changed the extent of lymphadenectomy. We report herein the interim analysis on the first 70 patients. After endoscopic ICG injection 24 h (n = 49) or 72 h (n = 21) ahead, 19, 20, and 31 patients underwent right colectomy, left colectomy, and anterior rectal resection. The extent of lymphadenectomy changed in 35 (50%) patients, mostly (29 (41.4%)) for the identification of LNs (median two) outside the standard draining basin. Identification of such LNs was less frequent in rectal tumors that had undergone chemoradiotherapy (26.3%) (p > 0.05). A non-significant correlation between time-to-ICG injection and identification of aberrant LNs was observed (48.9% at 24 h vs. 23.8% at 72 h). The presence of LN metastases did not affect a proper fluorescent mapping. These data indicate that ICG lymphatic mapping provides relevant information in 50% of patients, thus increasing the accuracy of potentially curative resections.

Prediction of lateral lymph node metastasis using OSNA method for mesorectal lymph nodes in low rectal cancer: A prospective study by the Kanagawa Yokohama Colorectal Cancer Study Group (KYCC1801)

BACKGROUND AND OBJECTIVES

Contrary to the Japanese guidelines recommendations regarding lateral lymph node dissection (LatLND) for rectal cancer, its omission is common in clinical practice without reliable omission criteria. Negative pathological mesorectal lymph node metastasis (MesLNM) is reportedly highly correlated with negative pathological lateral lymph node metastasis (p-LatLNM); however, this cannot be used as a criterion because pathological features are revealed postoperatively. Herein, we prospectively evaluated the negative predictive value (NPV) of MesLNM diagnosed via the one-step nucleic acid amplification (OSNA) method for p-LatLNM.

METHODS

This prospective study was conducted at a single academic study group in Japan. The key eligibility criterion was mid-to-low rectal cancer planned to be treated using mesorectal excision with LatLND. According to the study protocol, the OSNA method was considered useful if the point estimate of the NPV exceeded 95%.

RESULTS

Preoperative case registration was conducted between 2018 and 2020; 34 patients were registered. Among these, 16 were negative for OSNA-MesLNM, and negative p-LatLNM was confirmed in all cases. The point estimate of the NPV was 100%, with the 95% confidence interval ranging from 79.4% to 100.0%.

CONCLUSIONS

The OSNA method is useful in selecting patients in whom LatLND can be omitted in real-world clinical practice.

Clinical analysis of metastatic characteristics of infrapyloric lymph nodes (No.206) and terminal ileum lymph nodes in patients with right colon cancer

BACKGROUND

D3 or complete mesocolic excision (CME) surgery has become a common surgical procedure for the treatment of colon cancer metastasis. Clinical misuse and overuse of lymph node dissection bring unnecessary burdens to patients. A detailed guidance for lymph node dissection in patients with T3 and T4 stage right colon cancer at different locations is urgently needed.

METHODS

A retrospective study was performed. Patients received D3 or CME surgery were divided into ileocecal group, ascending colon group, and hepatic flexure group according to the 9th edition of the Japanese Society for Cancer of the Colon and Rectum guidelines. The distributions of lymph node metastases were analyzed according to tumor infiltration depth (T stage) and tumor location.

RESULTS

The incidence of metastases in the paracolic area (or station), intermediate area, and main (or central) area was 38.4% (139/362), 12.7% (46/362), and 9.7% (35/362), respectively. The proportion of patients having No.206 and terminal ileum lymph nodes metastases was 7.7% (14/181) and 3.7% (9/244), respectively. No.206 lymph node metastasis is related to tumor location (χ² = 7.955, p = 0.019) and degree of differentiation (χ² = 18.99, p = 0.000), and terminal ileum lymph node metastasis is related to tumor location (χ² = 6.273, p = 0.043). Patients with T3/T4 hepatic flexure cancer received radical right hemicolectomy in addition to No.206 lymph node dissection.

CONCLUSION

Radical right hemicolectomy and No.206 group lymph node dissection are necessary for T3 and T4 stage colon cancer therapy.

Routine CT evaluation of central vascular ligation in patients undergoing complete mesocolic excision for sigmoid colon cancer

AIM

Objective and reproducible quality measures of complete mesocolic excision (CME) for colon cancer are not currently available. This study aimed to measure the inferior mesenteric stump length following CME for sigmoid colon cancer and explore surgical, pathological and oncological outcomes in patients with a stump length of <10 mm vs. ≥10 mm.

METHOD

This was a single-centre, retrospective cohort study including patients undergoing minimally invasive surgery for sigmoid colon cancer between May 2013 and May 2015. Follow-up CT scans were reviewed, and a vascular stump cut-off of <10 mm for adequate central ligation of the inferior mesenteric artery was applied. Differences in perioperative, histopathological and oncological outcome parameters (overall, disease-free and recurrence-free survival) were explored between <10 mm vs. ≥10 mm groups.

RESULTS

A total of 127 patients (43% female) with a median age of 68 years were included. The median follow-up time was 68 months. CT measurements showed good interrater agreement (90% absolute agreement) and reliability among raters (kappa = 0.77, 95% CI 0.53-1.00, p < 0.001). A stump length ≥10 mm was associated with longer operating time (150 vs. 180 min, p = 0.021), intramesocolic resection (p = 0.008), and a shorter distance from the bowel wall to vascular tie (120 vs. 102 mm, p = 0.005).

CONCLUSION

An arterial stump length ≥10 mm in sigmoid resection for colon cancer was associated with key clinical quality measures. Measurement of arterial stump length using routine follow-up CT may serve as a quality indicator of vascular ligation in CME surgery.

Apical lymphadenectomy during low ligation of the IMA during rectosigmoid resection for cancer

Background

Low ligation of the inferior mesenteric artery with preservation of the left colic artery may decrease the risk of colorectal anastomotic ischemia compared to high ligation at its origin. Low ligation leaves apical nodes in situ and is therefore paired with apical lymphadenectomy. We sought to compare relevant oncologic outcomes between high ligation and low ligation plus apical lymphadenectomy in rectosigmoid resection for colorectal cancer.

Methods

We conducted a retrospective cohort study. Patients receiving a rectosigmoid resection for cancer between January 2012 and July 2018 were included. Patients with metastatic disease and those who underwent low ligation without apical lymphadenectomy were excluded. Our primary outcome was nodal yield/metastasis. Secondary outcomes included perioperative complications, local recurrence, and overall survival.

Results

Eighty-four patients underwent high ligation and 89 low ligation plus apical lymphadenectomy (median follow-up 20 months). In the low-ligation group, a median of 2 (interquartile range = 1–3) apical nodes was resected; 4.1% were malignant, increasing pathologic stage in 25% of these patients. There were no differences in nodal yield, complications, anastomotic leak, local recurrence, or overall survival.

Conclusion

No differences were identified between high ligation and low ligation plus apical lymphadenectomy with respect to relevant clinical outcomes. Prospective trial data are needed to robustly establish the oncologic benefit and safety of the low ligation plus apical lymphadenectomy technique.

Complete Mesocolic Excision and D3 Lymphadenectomy versus Conventional Colectomy for Colon Cancer: A Systematic Review and Meta-Analysis

BACKGROUNDS

Previous systematic reviews suggest that the implementation of 'complete mesocolon excision' (CME) for colon tumors entails better specimen quality but with limited long-term outcomes. We performed a meta-analysis to compare the pathological, perioperative, and oncological results of CME with conventional surgery (CS) in primary colon cancer.

METHODS

Embase, MEDLINE and CENTRAL databases were searched using Medical Subject Headings for CME and D3 lymphadenectomy. The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 18,989 patients from 27 studies were included. Postoperative complications were higher in the CME group (relative risk [RR] 1.13, 95% confidence interval [CI] 1.04-1.22, I² = 0%), while no differences were observed in terms of anastomotic leak (I² = 0%) or perioperative mortality (I² = 49%). CME was associated with a higher number of lymph nodes harvested (I² = 95%), distance to high tie (I² = 65%), bowel length (I² = 0%), and mesentery area (I² = 95%). CME also had positive effects on 3- and 5-year overall survival (RR 1.09, 95% CI 1.04-1.15, I² = 88%; and RR 1.05, 95% CI 1.02-1.08, I² = 62%, respectively) and 3-year disease-free survival (RR 1.10, 95% CI 1.04-1.17, I² = 22%), as well as decreased local (RR 0.35, 95% CI 0.24-0.51, I² = 51%) and distant recurrences (RR 0.71, 95% CI 0.60-0.85, I² = 34%).

CONCLUSIONS

Limited evidence suggests that CME improves oncological outcomes with a higher postoperative adverse events rate but no increase in anastomotic leak rate or perioperative mortality, compared with CS.

Colon cancer survival differs from right side to left side and lymph node harvest number matter

Background

Right-sided colorectal cancer (CRC) has worse survival than does left-sided CRC. The objective of this study was to further assess the impact of right-side location on survival and the role of the extent of lymphadenectomy.

Methods

All CRCs diagnosed between 2000 and 2012 in Emilia-Romagna Region, Italy, were included. Data for stage, grade, histology, screening history, and number of removed lymph nodes (LN) were collected. Multivariable Cox regression models were used to estimate hazard ratios (HR), with relative 95% confidence intervals (95%CI), of right vs. left colon and of removing < 12, 12–21 or > 21 lymph nodes by cancer site.

Results

During the study period, 29,358 patients were registered (8828 right colon, 18,852 left colon, 1678 transverse). Patients with right cancer were more often older, females, with advanced stage and high grade, and higher number of removed LNs. Five-year survival was lower in the right than in the left colon (55.2% vs 59.7%). In multivariable analysis, right colon showed a lower survival when adjusting for age, sex, and screening status (HR 1.12, 95%CI 1.04–1.21). Stratification by number of lymph nodes removed (12–21 or > 21) was associated with better survival in right colon (HR 0.54, 95%CI 0.40–0.72 and HR 0.40, 95%CI 0.30–0.55, respectively) compared to left colon (HR 0.89, 95%CI 0.76–1.06 and HR 0.83, 95%CI 0.69–1.01, respectively).

Conclusions

This study confirms that right CRC has worse survival; the association is not due to screening status. An adequate removal of lymph nodes is associated with better survival, although the direction of the association in terms of causal links is not clear.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10746-4.

Robotic complete mesocolic excision versus conventional robotic right colectomy for right-sided colon cancer: a comparative study of perioperative outcomes

AIM

This study aims to compare the short-term outcomes of robotic complete mesocolic excision (RCME) versus conventional robotic right colectomy (RRC) for right-sided colon cancer.

METHODS

Consecutive patients who underwent robotic surgery for right-sided colon cancer in a public quaternary and a private tertiary healthcare centre between November 2018 and June 2020 were included. Clinical, perioperative and histopathological variables were collected and analysed.

RESULTS

Fifty-one patients were included; 25 (49%) of them had an RCME. The groups were evenly distributed in terms of demographic characteristics and tumour location. Operative time was similar between both groups, and no patients required conversion to open surgery. There were no differences in overall complications (16% in RCME vs. 26.9% in RRC; p = 0.499) or their profile between groups. There were no anastomotic leaks recorded, and the reoperation rates were similar (0% for RCME versus 3.8% for RRC; p = 1). In addition, the median length of hospital stay was similar in between the RCME and the RRC groups (4 [4-6] days versus 5 [3-8.5] days, respectively; p = 0.891). Whilst there were no differences in the TNM staging, the mean number of lymph nodes harvested with RCME was 37.7 (±12.9) compared to 21.8 (±7.5) with RCC (p < 0.001).

CONCLUSION

In our series, RCME was associated with a higher lymph node harvest and a similar morbidity profile compared to RCC. Further studies are required to validate these results and provide long-term oncologic outcomes.

Impact of D3 lymph node dissection on upstaging and short-term survival in clinical stage I right-sided colon cancer

BACKGROUND

D3 lymph node dissection is becoming the standard procedure for the treatment of advanced right colon cancer and has shown increasing evidence of its oncologic benefit. However, a clear indication for its application is lacking and data on this topic is unsatisfactory. Thus, the necessity for D3 lymph node dissection in clinical stage I right colon cancer remains controversial.

METHODS

We retrospectively analyzed data from clinical stage I right colon cancer patients who underwent radical surgery at three hospitals of Korea university medical center between January 2015 and June 2018. We compared surgical complications and short-term oncologic outcomes between D2 and D3 lymph node dissections in these patients.

RESULTS

Among 512 patients, 122 (23.8%) were clinical stage I. Of these, 88 and 34 patients received D2 and D3 lymph node dissection, respectively. There were no statistically significant differences in clinicopathologic variables and surgical outcomes between the two groups. Upstaging occurred in 16 patients (47.1%) in the D3 group and 23 patients (26.1%) in the D2 group. There were four recurrences in the D2 group but no recurrence in the D3 group. Log-rank tests showed no statistically significant difference in disease-free survival rates between the two groups (p = 0.210).

CONCLUSION

There was no significant difference in disease-free survival rates between D2 and D3 lymph node dissection in clinical stage I right colon cancer patients. However, recurrence occurred in the D2 group. Efforts to improve the accuracy of clinical staging are required and more studies with better quality are needed.

Infrapyloric lymph node dissection in right hemicolectomy for colon cancer: Should prophylactic resection be recommended?

BACKGROUND AND OBJECTIVES

Infrapyloric lymph node dissection in right colon cancer patients remains controversial. We aimed to investigate the pattern of infrapyloric lymph node metastasis in right colon cancer patients.

METHODS

Clinical and pathological data of 140 colon cancer patients who underwent radical right hemicolectomy and infrapyloric lymph node dissection were retrospectively examined. Patient characteristics, intraoperative conditions, postoperative recovery information, postoperative pathological findings, and follow-up data were examined.

RESULTS

About 19, 44, 73, and 4 patients had tumors located in the cecum, ascending colon, hepatic flexure, and right side of the transverse colon, respectively. The median number of harvested lymph nodes and that of positive lymph nodes were 24 (16-30) and 1 (0-7.75), respectively. The lymph node metastasis rate was 41.43% (58/140). The corresponding values for infrapyloric lymph nodes were 3 (1-4), 0 (0-0), and 0.71% (1/140), respectively. The median follow-up duration was 19 (0-65) months in 131 (93.6%) patients. The 5-year overall and disease-free survival rates were 86.3% and 73.5%, respectively.

CONCLUSION

Given the low rate of infrapyloric lymph node metastasis in right colon cancer, lymph node dissection is recommended in patients with locally advanced colon cancer at the hepatic flexure and those with suspected infrapyloric lymph node metastasis.

Oncological reasons for performing a complete mesocolic excision: a systematic review and meta-analysis

BACKGROUND

While complete mesocolic excision (CME) has been shown to have an oncological benefit as compared to conventional colonic surgery for colon surgery, this benefit must be weighed up against the risk of major intra-abdominal complications. This paper aimed to assess the comparative oncological benefits of CME.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic review of the literature until May 2020 was performed. Comparative studies assessing CME versus conventional colonic surgery for colon cancer were compared, and outcomes were pooled.

RESULTS

A total of 700 publications were identified, of which 19 were found to meet the inclusion criteria. A total of 25 886 patients were compared, with 14 431 patients in the CME arm. CME was associated with a significantly higher rate of vascular injury (odds ratio 3, P < 0.001). Rates of local and distant recurrence were lower in the CME group (odds ratio 0.66 and 0.73, respectively, both P < 0.001). CME patients had a significantly higher lymph node yield (P < 0.001). While no significant differences were noted between the two groups in terms of pooled 3- or 5-year disease-free survival, pooled 5-year overall survival was significantly higher in the CME group (relative risk 0.82, P < 0.001).

CONCLUSION

Based on the available evidence, CME is associated with improved oncologic outcomes at the expense of higher complication rates, including vascular injury. The oncological benefits need to weighed up against a multitude of factors including the level of hospital support, surgeon experience, patient age, and associated comorbidities.

Robotic complete mesocolic excision and central vascular ligation for right-sided colon cancer: short-term outcomes from a case series

BACKGROUND

Despite conflicting data regarding oncological outcomes, studies demonstrate that complete mesocolic excision (CME) and central vascular ligation (CVL) for right-sided colon cancer removes significantly more tissue and yields higher lymph node counts when compared to conventional resection. This study aims to report the safety profile of CME and CVL in patients undergoing robotic surgery for right-sided colon cancer during the introduction of this technique across two institutions.

METHODS

Patients who underwent an elective robotic right colectomy with CME and CVL for right-sided colon cancer in a public quaternary and a private tertiary healthcare centre between November 2018 and April 2020 were included. Demographic, clinical, perioperative and histopathological variables were recorded and analysed.

RESULTS

Twenty patients (13 females) with a median age of 69 (23-83) years and median body mass index of 27 (19-46) were included. All of them had a pre-operative diagnosis of right-sided colon adenocarcinoma. Median operative time and blood loss were 140 (130-300) min and 30 (20-100) mL, respectively. There were no conversions or intra-operative complications. There were two post-operative complications recorded (one ileus and one intra-abdominal collection treated with intravenous antibiotics) and no re-interventions. Median length of stay was 4 (2-8) days. All patients had an R0 resection, and the median lymph node yield was 36 (22-80) lymph nodes.

CONCLUSION

This series demonstrates a safe introduction of robotic CME and CVL in patients with right-sided colon cancer. The lymph node harvest obtained with CME and CVL in this setting was high.

Laparoscopic complete mesocolic excision with D3 lymph node dissection for right colon cancer in elderly patients

Complete mesocolic excision (CME) with D3 lymph node dissection is considered an oncological surgery for right colon cancer. However, there is still controversy for extensive oncological surgery in elderly patients. The aim of this study is to evaluate the safety and oncological outcomes of laparoscopic CME with D3 lymph node dissection for right colon cancer in elderly patients. Patients who underwent laparoscopic right colectomy, from 2004 to 2014, were divided into Groups A (age ≥ 70 years, n = 80) or B (age < 70 years, n = 127). Short and long-term outcomes were analysed. Basic demographics and short-term surgical outcomes were similar between groups. Among pathological outcomes, the mean number of harvested lymph nodes was significantly less in Group A. Adjuvant chemotherapy refusal rate was significantly higher in Group A. Overall and recurrence-free survival were similar between groups. We found laparoscopic CME with D3 lymph node dissection is a safe and feasible surgical option for right colon cancer in elderly patients.

Optimal extent of central lymphadenectomy for right-sided colon cancers: is lymphadenectomy beyond the superior mesenteric vein meaningful?

PURPOSE

The objective of the current study was to assess the therapeutic benefit of lymphadenectomy according to the extent of lymphadenectomy.

METHODS

Patients undergoing colectomy for right-sided colon cancer were identified. Distribution of lymph node metastases (DLNM) of 1, 2 and 3 were defined as lymph node metastasis (LNM) in the pericolic nodes, the intermediate nodes and the front of the SMV near the origin of the major artery, respectively. The therapeutic index (TI) was calculated based on the frequency of LNM and the 5 year overall survival (OS) rate of patients with LNM.

RESULTS

Among 344 patients who met the inclusion criteria, roughly half had LNM (n = 150, 43.7%). While 107 (31.1%) and 30 (8.7%) patients had DLNM1 and DLNM2, respectively, only 13 patients (3.8%) were defined as DLNM3. However, there was no significant difference in 5 year OS by DLNM (DLNM1 71.1%, DLNM2 78.7%, DLNM3 50.4%, p = 0.61). Overall, the TI of lymphadenectomy for D3 area was approximately 1/10 of the TI for D1 (1.9 vs.22.1), given the low frequency of LNM (3.8%) and poor 5 year OS of patients with LNM (50.4%). This trend was consistent irrespective of primary tumor locations.

CONCLUSION

The survival benefit from central lymphadenectomy namely D3 was low among patients with right-sided colon cancers.

Efficacy and Safety of Complete Mesocolic Excision in Patients With Colon Cancer: Three-year Results From a Prospective, Nonrandomized, Double-blind, Controlled Trial

OBJECTIVE

The aim of the study was to evaluate the oncological outcomes of complete mesocolic excision (CME) in colon cancer patients.

SUMMARY BACKGROUND DATA

CME is considered a standard procedure for colon cancer patients. However, previous evidence regarding the effect of CME on prognosis has fundamental limitations that prevent it from being fully accepted.

METHODS

Patients who underwent radical resection for colon cancer were enrolled between November 2012 and March 2016. According to the principles of CME, patients were stratified into 2 groups based on intraoperative surgical fields and specimen photographs. The primary outcome was local recurrence-free survival (LRFS). The clinicopathological data and follow-up information were collected and recorded. The final follow-up date was April 2016. The trial was registered in ClinicalTrials.gov (identifier: NCT01724775).

RESULTS

There were 220 patients in the CME group and 110 patients in the noncomplete mesocolic excision (NCME) group. Baseline characteristics were well balanced. Compared with NCME, CME was associated with a greater number of total lymph nodes (24 vs 20, P = 0.002). Postoperative complications did not differ between the 2 groups. CME had a positive effect on LRFS compared with NCME (100.0% vs 90.2%, log-rank P < 0.001). Mesocolic dissection (100.0% vs 87.9%, log-rank P < 0.001) and nontumor deposits (97.2% vs 91.6%, log-rank P < 0.022) were also associated with improved LRFS.

CONCLUSIONS

Our findings demonstrate that, compared with NCME, CME improves 3-year LRFS without increasing surgical risks.

Colorectal cancer treated by resection and extended lymphadenectomy: patterns of spread in left- and right-sided tumours

BACKGROUND

Whether tumour side affects the anatomical extent and distribution of lymph node metastasis in colon cancer is unknown. The impact of tumour side on the anatomical pattern of lymphatic spread in colon cancer was assessed.

METHODS

Patients with stage III colon cancer from a Japanese multi-institutional database who underwent extensive (D3) lymphadenectomy, which is similar in concept to complete mesocolic excision with central venous ligation, were divided into groups with right- and left-sided tumours. Based on location, mesenteric lymph nodes were categorized as paracolic (L1), intermediate (L2) or central (L3). The Kaplan-Meier method was used to evaluate disease-free survival (DFS) and overall survival (OS), and multivariable Cox models were used to evaluate the association between anatomical lymph node level, metastatic pattern and outcome.

RESULTS

A total of 4034 patients with stage III colon cancer (right 1618, left 2416) were included. Unadjusted OS was worse in patients with right colon cancer (hazard ratio 1·23, 95 per cent c.i. 1·08 to 1·40; P = 0·002), but DFS was similar. Right-sided tumours more frequently invaded L3 nodes than left-sided lesions (8·5 versus 3·7 per cent; P < 0·001). The proportion of patients with a skipped pattern of lymphatic spread was higher in right than in left colon cancer (13·7 versus 9·0 per cent; P < 0·001). In multivariable analysis, invasion of L3 nodes was associated with worse OS in left but not in right colon cancer. The presence of skipped metastasis was associated with worse DFS in left, but not right, colon cancer.

CONCLUSION

There are significant differences in the pattern of lymph node invasion between right- and left-sided stage III colon cancer, and in their prognostic significance, suggesting that tumour side may dictate the operative approach.

A Proposal for Novel Standards of Histopathology Reporting for D3 Lymphadenectomy in Right Colon Cancer: The Mesocolic Sail and Superior Right Colic Vein Landmarks

BACKGROUND

Strong agreement exists concerning the standards of pathologic reporting for total mesorectal excision and complete mesocolic excision. It represents a quality standard that correlates with survival. However, no agreed standards of reporting are available to define D3 lymphadenectomy for right colectomy.

OBJECTIVE

The purpose of this study was to define anatomopathological standards of specimen quality obtained from the surgical specimen when an oncologic right hemicolectomy with D3 lymphadenectomy has been correctly performed.

DESIGN

This study was conducted in 2 different phases. The first part consisted of a cadaver-based study of right colon anatomy, and the second part consisted of a prospective assessment of a series of surgical specimens obtained after right hemicolectomy for cancer.

SETTINGS

The anatomic phase of the study was performed in collaboration with the University of Valencia Department of Anatomy and Embryology. The second part was performed at a colorectal unit of a tertiary hospital.

PATIENTS

Seventeen cadavers were used for the first phase, and 65 surgical specimens were examined for the second part of the study.

MAIN OUTCOME MEASURES

In each specimen, the pathologists looked for anatomic structures defined as markers of quality standards of the D3 lymphadenectomy during the first phase. Specimens were classified as complete, partial, and incomplete D3 lymphadenectomy.

RESULTS

Twenty percent of specimens were classified as incomplete D3 lymphadenectomy, 31% as partial, and 49% as complete. A median number of 14 (6-64), 22 (11-47), and 29 (14-55) lymph nodes were isolated (p = 0.01). Similarly, the median numbers of lymph nodes isolated in the area of D3 lymphadenectomy were 0 in incomplete, 1 (0-5) in Partial, and 3 (0-8) in Complete D3 lymphadenectomy specimens (p = 0.0001).

LIMITATIONS

A large multicenter study with adequate power is needed.

CONCLUSIONS

We propose the right mesocolic sail and trunk of superior right colic vein as new and reproducible anatomopathologic standards of D3 lymphadenectomy in oncologic right hemicolectomy. See Video Abstract at http://links.lww.com/DCR/B149. PROPUESTA PARA NUEVOS ESTÁNDARES HISTOPATOLÓGICOS EN LA LINFADENECTOMÍA D3 EN EL CÁNCER DE COLON DERECHO: LA VELA MESOCÓLICA Y LA VENA CÓLICA DERECHA SUPERIOR: Existe un claro acuerdo sobre los estándares de calidad patológicos para la escisión total del mesorrecto y la escisión completa del mesocolon. Son considerados "estándar de calidad" que se correlaciona con la supervivencia. Sin embargo, no se dispone de estándares de calidad para definir la linfadenectomía D3, en la colectomía derecha.Definir los estándares anatomopatológicos de calidad obtenidos de una muestra quirúrgica, cuando se ha realizado correctamente una hemicolectomía derecha oncológica, con linfadenectomía D3.Dos fases diferentes. La primera parte consistió en un estudio basado en la anatomía del colon derecho, realizado en cadáveres, y la segunda parte consistió en una evaluación prospectiva de una serie de muestras quirúrgicas obtenidas después de la hemicolectomía derecha para cáncer.La fase anatómica del estudio se realizó en colaboración con el Departamento de Anatomía y Embriología de la Universidad de Valencia. La segunda parte se realizó en la Unidad Colorrectal de un hospital terciario.Se utilizaron diecisiete cadáveres para la primera fase y se examinaron 65 muestras quirúrgicas para la segunda parte del estudio.En cada muestra, los patólogos buscaron estructuras anatómicas definidas, como marcadores de los estándares de calidad de la linfadenectomía D3, durante la primera fase. Las muestras se clasificaron como linfadenectomía D3 completa, parcial e incompleta.El veinte por ciento de las muestras se clasificaron como "Linfadenectomía D3 Incompleta", el 31% como "Parcial" y el 49% como "Completa." Se aisló una media de 14 (6-64), 22 (11-47) y 29 (14-55) ganglios linfáticos respectivamente (p = 0,01). Del mismo modo, el número medio de ganglios linfáticos aislados en el área de la linfadenectomía D3 fue 0 en "Incompleta", 1 (0-5) en "Parcial" y 3 (0-8) en muestras de "Linfadenectomía D3 Completa" (p = 0,0001).Se necesita un estudio multicéntrico con potencia adecuada.Proponemos la vela mesocólica derecha y el tronco de la vena cólica derecha superior, como estándares anatomopatológicos nuevos y reproducibles de linfadenectomía D3, en hemicolectomía derecha oncológica. Consulte Video Resumen en http://links.lww.com/DCR/B149.

Indocyanine Green Fluorescence Imaging-Guided Laparoscopic Surgery Could Achieve Radical D3 Dissection in Patients With Advanced Right-Sided Colon Cancer

BACKGROUND

The optimal lymph node dissection with central vascular ligation is an important part for oncological outcomes after laparoscopic right-sided colon cancer surgery. Few studies have examined the clinical value of indocyanine green fluorescence imaging-guided D3 dissection for right-sided colon cancer.

OBJECTIVES

We assessed the clinical value of indocyanine green fluorescence imaging-guided laparoscopic surgery in improving the radicality of lymph node dissection for right-sided colon cancer by comparing the outcomes of conventional laparoscopic surgery.

DESIGN

The data were retrospectively reviewed and analyzed.

SETTING

This study was conducted at a single university hospital.

PATIENTS

A 1:2 matched case-control study included 25 patients undergoing fluorescence imaging-guided laparoscopic surgery and 50 patients undergoing conventional laparoscopic surgery for clinical T3 or T4 right-sided colon cancer between June 2016 and December 2017.

MAIN OUTCOME MEASURES

The extent of D3 dissection and pathological results (tumor stage, lymph node yield, and number of metastatic lymph nodes) were analyzed.

RESULTS

The 2 groups were similar in baseline characteristics. The numbers of harvested pericolic and intermediate lymph nodes were not different between the 2 groups. The numbers of central lymph nodes (14 vs 7, p < 0.001) and total harvested lymph nodes (39 vs 30, p = 0.003) were significantly higher in the fluorescence group than in the conventional group. In the multivariate analysis, the use of indocyanine green fluorescence imaging was an independently related factor for the retrieval of higher numbers of overall and central lymph nodes. The number of metastatic lymph nodes was not significantly different between the 2 groups.

LIMITATIONS

The results of this study were limited by its small patient numbers and retrospective nature.

CONCLUSIONS

Real-time indocyanine green fluorescence imaging of lymph nodes may improve the performance of more radical D3 lymph node dissection during laparoscopic right hemicolectomy for advanced right-sided colon cancer. See Video Abstract at http://links.lww.com/DCR/B150. LA CIRUGÍA LAPAROSCÓPICA GUIADA POR IMÁGENES DE FLUORESCENCIA VERDE INDOCIANINA PODRÍA LOGRAR UNA DISECCIÓN RADICAL D3 EN PACIENTES CON CÁNCER DE COLON AVANZADO DEL LADO DERECHO: La disección óptima de los ganglios linfáticos con ligadura vascular central es una parte importante para los resultados oncológicos después de la cirugía laparoscópica de cáncer de colon del lado derecho. Pocos estudios han examinado el valor clínico de la disección D3 guiada por imágenes de fluorescencia verde indocianina para el cáncer de colon del lado derecho.Evaluamos el valor clínico de la cirugía laparoscópica guiada por imagen de fluorescencia verde indocianina para mejorar la radicalidad de la disección de ganglios linfáticos para el cáncer de colon del lado derecho mediante la comparación de los resultados de la cirugía laparoscópica convencional.Los datos se revisaron y analizaron retrospectivamente.Este estudio se realizó en un solo hospital universitario.Un estudio de casos y controles emparejado 1:2 incluyó a 25 pacientes sometidos a cirugía laparoscópica guiada por imágenes de fluorescencia y 50 pacientes sometidos a cirugía laparoscópica convencional para cáncer de colon derecho clínico T3 o T4 entre Junio de 2016 y Diciembre de 2017.Se analizó el alcance de la disección D3 y los resultados patológicos (estadio tumoral, rendimiento de los ganglios linfáticos y número de ganglios linfáticos metastásicos).Los dos grupos fueron similares en las características basicas. El número de ganglios linfáticos pericólicos e intermedios recolectados no fue diferente entre los dos grupos. El número de ganglios linfáticos centrales (14 vs 7, p < 0.001) y el total de ganglios linfáticos recolectados (39 vs 30, p = 0.003) fueron significativamente mayores en el grupo de fluorescencia que en el grupo convencional. En el análisis multivariante, el uso de imágenes de fluorescencia verde indocianina fue un factor independiente relacionado para la recuperación de un mayor número de ganglios linfáticos centrales y globales. El número de ganglios linfáticos metastásicos no fue significativamente diferente entre los dos grupos.Los resultados de este estudio fueron limitados por su pequeño número de pacientes y su naturaleza retrospectiva.Las imágenes de fluorescencia verde indocianina en tiempo real de los ganglios linfáticos pueden mejorar el rendimiento de la disección más radical de los ganglios linfáticos D3 durante la hemicolectomía derecha laparoscópica para el cáncer de colon avanzado del lado derecho. Consulte Video Resumen en http://links.lww.com/DCR/B150.

Laparoscopic segmental left colectomy for splenic flexure carcinoma: a single institution experience

BACKGROUND

There is ongoing debate regarding surgical treatment of splenic flexure cancer. The main points of controversy include the appropriate extent of colon resection, either to the right or to the left, and the appropriate extent of lymph-node dissection. The aim of this study was to review our experience in laparoscopic treatment of splenic flexure cancer cases and to compare our data to the recent literature.

METHODS

Consecutive patients, operated on for splenic flexure colon carcinoma at a single institution between April 2005 and January 2013, were included in the study. Exclusion criteria were a previous history of colorectal cancer, recurrent colonic cancer, emergency cases with an obstructive tumor or a perforated tumor with peritonitis, synchronous cancer, palliative surgery, and a past history of colorectal resection. Patients underwent laparoscopic segmental left colectomy with ligation of the left branch of the middle colic and of the left colic artery. Patient characteristics, operative and postoperative outcomes, and long-term technical, functional, and oncological results from a prospectively maintained database were retrospectively analyzed. After hospital discharge, standardized follow-up was performed at 1 month postoperatively, then every 3 months during the first 2 years, and every 6 months thereafter, for a total of 5 years.

RESULTS

A total of 28 consecutive patients (16 males) with a median age of 71.8 years (range 42.5-88.8 years) were included. Ninety-day mortality was 3.5% and surgical morbidity was 21.5% with anastomotic leak rate of 10.7%. All survivors experienced good or very good functional results. During a median follow-up period of 50.9 months, eight patients (28.5%) presented with a recurrence. The 5-year overall and disease-free survival rates were 46.3% and 39.2%, respectively.

CONCLUSIONS

Segmental left colectomy for splenic flexure carcinoma is associated with reasonably low morbidity and very good functional results. However, survival rates are low.

5-year outcome after complete mesocolic excision for right-sided colon cancer: a population-based cohort study

BACKGROUND

The benefits of extensive lymph node dissection as performed in complete mesocolic excision are still debated, although recent studies have shown an association with improved long-term outcomes. However, none of these studies had an intention-to-treat design or aimed to show a causal effect; therefore in this study, we aimed to estimate the causal oncological treatment effects of complete mesocolic excision on right-sided colon cancer.

METHODS

We did a population-based cohort study involving prospective data collected from four hospitals in Denmark. We compared the oncological outcome data of patients at one centre performing central lymph node dissection and vascular division after almost complete exposure of the proximal part of the superior mesenteric vein (ie, the complete mesocolic excision group) with three other centres performing conventional resections with unstandardised and limited lymph node dissection (ie, non-complete mesocolic excision; control group). We included data for all patients in the Capital Region of Denmark undergoing elective curative-intent right-sided colon resections for stages I-III colon cancer, as categorised by the Union for International Cancer Control (UICC; 5th edition), from June 1, 2008, to Dec 31, 2013. Patients were followed-up for 5·2 years after surgery. The primary outcome was the cumulative incidence of recurrence after 5·2 years of surgery. Inverse probability of treatment weighting and competing risk analyses were used to estimate the possible causal effects of complete mesocolic excision. This study is registered with ClinicalTrials.gov, number NCT03754075.

FINDINGS

1069 patients (813 in the control group and 256 in the complete mesocolic excision group) underwent curative-intent elective surgery for right-sided colon cancer during the study period. None of the patients were lost to follow-up regarding survival or recurrence status, and consequently no patient was censored in the analyses. The 5·2-year cumulative incidence of recurrence was 9·7% (95% CI 6·3-13·1) in the complete mesocolic excision group compared with 17·9% (15·3-20·5) in the control group, and the absolute risk reduction of complete mesocolic excision after 5·2 years was 8·2% (95% CI 4·0-12·4; p=0·00015). In the control group, 145 (18%) of 813 patients were diagnosed with a recurrence and 281 (35%) died during follow-up, whereas in the complete mesocolic excision group 25 (10%) of 256 patients were diagnosed with a recurrence and 75 (29%) died during follow-up.

INTERPRETATION

This study shows a causal treatment effect of central mesocolic lymph node excision on risk of recurrence after resection for right-sided colon adenocarcinoma. Complete mesocolic excision has the potential to reduce the risk of recurrence and improve long-term outcome after resection for all UICC stages I-III of right-sided colon adenocarcinomas.

FUNDING

The Tvergaard Fund, Helen Rude Fund, Krista and Viggo Petersen Fund, Olga Bryde Nielsen Fund, and Else and Mogens Wedell-Wedellsborg Fund.