Lymph node distribution and pattern of metastases in the mesorectum following total mesorectal excision using the modified fat clearing technique

Can we apply the concept of sentinel lymph node in rectal cancer surgery?

INTRODUCTION

Colorectal cancer remains one of the most common causes of cancer-related mortality worldwide, and lymph node staging is crucial in the diagnostic and therapeutic process. Sentinel lymph nodes are the first involved in this process, but their validity in colorectal surgery has not yet been established. Following the emergence of new imaging instrumentation, some authors have attempted to propose different techniques for lymph node identification. However, a clear pattern of mesorectal lymph node distribution relative to the primary lesion site has yet to be defined.

MATERIAL AND METHODS

Our analysis retrospectively reviewed suspicious mesorectal pathological lymph nodes on pre-operative magnetic resonance imaging (MRI) of rectal cancer patients, in order to assess the distribution patterns of possible tumour-related rectal lymph nodes. Mesorectal space was subdivided into quadrants and levels, and morphological features and distances from the lymph node to the primary rectal tumour were recorded.

RESULTS

Two hundred and fifty-five mesorectal lymph nodes distributed among 60 patients were collected. Results show that in 92.1% of cases, nodes were distributed in the same mesorectal quadrant as the rectal primary tumour, and in 88.5% of cases, they were found at the same level as the rectal primary tumour.

CONCLUSIONS

Although a clear node distribution pattern was not established, these results may suggest at least a lymphatic drainage preference lane, worthy of further investigation.

Lateral Lymph Node Dissection for Locally Advanced Rectal Carcinoma: A Step-by-Step Description of Surgical Anatomical Planes During Cadaveric Dissection and Minimally Invasive Surgery

PURPOSE

Total mesorectal excision (TME) is accepted as gold standard method in rectal cancer globally. But there is no standard for lateral lymph nodes. Combination of neoadjuvant treatment plus lateral lymph node dissection (LLND) in select patients might be a promising method. Our purpose is to describe the anatomic landmarks of LLND on cadavers and minimally invasive surgery.

MATERIALS AND METHODS

Local advanced rectal cancer and lateral lymph node (LLN) metastasis are accepted as an indication of neoadjuvant treatment. LLND was performed according to preoperative imaging after radiochemotherapy.

RESULTS

Twenty-eight (10.5%) of 267 patients with rectal cancer who had suspected lateral lymph node metastasis (LLNM) with magnetic resonance imaging (MRI) underwent LLND in addition to TME after neoadjuvant chemoradiotherapy. Eight of them had LLNM. Three patients had bilateral LLND and only 1 had LLNM. The median number of harvested lymph nodes was 6. The rates of LLNM increased with the presence of poor prognosis markers. One regional and 1 distant recurrence were detected in patients who had no LLN metastasis compared with2 regional and 4 distant recurrences in the LLN-positive group.

CONCLUSIONS

Local advanced rectal cancer cases may benefit from LLND, but it does not appear to have an effect on overall survival. There is no consensus whether size and/or morphologic criteria in MRI are the ideal guide for LLND.

Low Rectal Cancers at Initial Staging MRI

Low rectal cancers, which are associated with increased risk of local recurrent disease and poorer prognosis, have unique anatomic considerations and issues for staging and treatment that do not apply to mid and high rectal cancers. Although tumor histology help drive the staging and treatment of all rectal cancers, it is of particular importance in low rectal cancers, which may involve the anal canal, to help establish whether a low rectal mass should be staged and treated as a rectal cancer (ie, adenocarcinoma) or an anal cancer (ie, squamous cell carcinoma). Optimal staging and treatment of rectal cancer are contingent on tumor location and local extent, which help guide management decisions including neoadjuvant therapy and curative surgical treatment strategies. Tumor location in the low rectum and local involvement of the anal canal, sphincter, and pelvic floor help determine whether a patient can undergo sphincter-preserving resection such as a low anterior resection versus abdominoperineal resection to achieve negative surgical margins. Issues exist related to the anatomy and patterns of disease spread that are unique to the low rectum and include how to determine and stage anal sphincter involvement, mesorectal fascia status at the pelvic floor, and nodal status of extramesorectal nodes such as the external iliac and inguinal lymph nodes. For these reasons, it is imperative that radiologists who interpret rectal cancer staging MRI examinations feel comfortable with the unique anatomy of the low rectum and anal canal, nuances of low rectal cancer local disease spread, and treatment paradigms for low rectal cancer. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Gollub in this issue.

Visualization of the carotid body in situ in fixed human carotid bifurcations using a xylene-based tissue clearing method

The anatomy of the carotid body (CB) and its nerve supply are important, because it is a potential therapeutic target for treatment of various clinical conditions. Visualization of the CB in situ in fixed human anatomical specimens is hampered by obscuring adipose and connective tissues. We developed a tissue clearing method to optimize identification of the CB. We used single sided carotid bifurcations of six human cadavers fixed long term. Visualization of the CB was accomplished by clearing tissue with xylene. Under incident light, carotid bifurcations exhibited a less transparent, darker colored CB; hematoxylin and eosin stained paraffin sections confirmed its identity. Our visualization of the CB in situ in human carotid bifurcations fixed long term enabled targeted resection and subsequent topographic and morphometric measurements of the CB. Our procedure does not interfere with immunohistochemical staining of sections prepared from such specimens.

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

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

Lymph Nodes Evaluation in Rectal Cancer: Where Do We Stand and Future Perspective

The assessment of nodal involvement in patients with rectal cancer (RC) is fundamental in disease management. Magnetic Resonance Imaging (MRI) is routinely used for local and nodal staging of RC by using morphological criteria. The actual dimensional and morphological criteria for nodal assessment present several limitations in terms of sensitivity and specificity. For these reasons, several different techniques, such as Diffusion Weighted Imaging (DWI), Intravoxel Incoherent Motion (IVIM), Diffusion Kurtosis Imaging (DKI), and Dynamic Contrast Enhancement (DCE) in MRI have been introduced but still not fully validated. Positron Emission Tomography (PET)/CT plays a pivotal role in the assessment of LNs; more recently PET/MRI has been introduced. The advantages and limitations of these imaging modalities will be provided in this narrative review. The second part of the review includes experimental techniques, such as iron-oxide particles (SPIO), and dual-energy CT (DECT). Radiomics analysis is an active field of research, and the evidence about LNs in RC will be discussed. The review also discusses the different recommendations between the European and North American guidelines for the evaluation of LNs in RC, from anatomical considerations to structured reporting.

T stage-dependent lymph node and distant metastasis and the accuracy of lymph node assessment in rectal cancer

Objective

To analyze data obtained in a representative number of patients with primary rectal cancer with respect to lymph node diagnostics and related tumor stages.

Methods

In pT2-, pT3-, and pT4 rectal cancer lesions, the impact of investigated lymph nodes on the frequency of pN+ status, the cumulative risk of metachronous distant metastases, and overall survival was studied by means of a prospective multicenter observational study over a defined period of time.

Results

From 2000 to 2011, the proportion of surgical specimens with ≥ 12 investigated lymph nodes increased significantly, from 73.6% to 93.2% (p < 0.001; the number of investigated lymph nodes from 16.2 to 20.8; p < 0.001). Despite this, the percentage of pN+ rectal cancer lesions varied only non-significantly (39.9% to 45.9%; p = 0.130; median, 44.1%). For pT2-, pT3-, and pT4 rectal cancer lesions, there was an increasing proportion of pN+ findings correlating significantly with the number of investigated lymph nodes up to n = 12 investigated lymph nodes. Only in pT3 rectal cancer was there a significant increase in pN+ findings in case of > 12 lymph nodes (p = 0.001), but not in pT2 (p = 0.655) and pT4 cancer lesions (p = 0.256). For pT3pN0cM0 rectal cancer, the risk of metachronous distant metastases and overall survival did not depend on the number of investigated lymph nodes.

Conclusion

In rectal cancer, at least n = 12 lymph nodes are to be minimally investigated. The investigation of fewer lymph nodes is associated with a higher risk of false-negative pN0 findings. In particular, in pT3 rectal cancer, the investigation of more than 12 lymph nodes lowers the risk of false-negative pN0 findings. An upstaging effect by the investigation of a possibly maximal number of lymph nodes could not be detected.

Downstaged ypT0-2N0 rectal cancer after neoadjuvant chemoradiation therapy may not need adjuvant chemotherapy: a retrospective cohort study

PURPOSE

Current guidelines suggest that adjuvant chemotherapy (AC) be administered to all locally advanced (clinically T3-4 or N-positivity) rectal cancer patients undergoing neoadjuvant chemoradiotherapy (nCRT) and radical surgical resection regardless of the final pathological staging (yp staging). This study aimed to evaluate the necessity of AC for ypT0-2N0 rectal cancer.

METHODS

Patients with ypT0-2N0 rectal cancer, who received nCRT and radical surgical resection, were recruited retrospectively at a university hospital. The main outcome was to evaluate the 5-year overall survival (OS) and disease-free survival (DFS) between ypT0-2N0 rectal cancer patients with AC and those without AC. We also identified potential independent prognostic factors associated with poor outcomes.

RESULTS

One hundred and ten ypT0-2N0 rectal cancer patients (ypT0: n = 6; ypT1: n = 44; ypT2: n = 60) were followed up for a median of 60 months. No significant difference was observed in DFS and 5-year OS between patients with AC and those without AC. The risk of recurrence was associated with the postoperative pathological staging (0% with ypT0, 2.4% with ypT1, and 10% with ypT2). In the multivariate analysis, retrieval of < 12 lymph nodes was an independent favorable prognostic factor, which correlated with a higher OS (HR: 2.263; 95% CI: 1.093-4.687, P = 0.028). Intra-tumor lymphovascular and perineural invasion were poor prognostic markers for shorter DFS (HR: 5.940; 95% CI: 1.150-30.696, P = 0.033).

CONCLUSION

Postoperative AC is not required for patients with ypT0-2N0 rectal cancer downstaged by nCRT, especially in those without poor prognostic factors.

MRI of rectal cancer-relevant anatomy and staging key points

Rectal cancer has the eighth highest cancer incidence worldwide, and it is increasing in young individuals. However, in countries with a high human development index, mortality is decreasing, which may reflect better patient management, imaging being key. We rely on imaging to establish the great majority of clinical tumour features for therapeutic decision-making, namely tumour location, depth of invasion, lymph node involvement, circumferential resection margin status and extramural venous invasion. Despite major improvements in technique resulting in better image quality, and notwithstanding the dissemination of guidelines and examples of standardised reports, rectal cancer staging is still challenging on the day-to-day practice, and we believe there are three reasons. First, the normal posterior pelvic compartment anatomy and variants are not common knowledge to radiologists; second, not all rectal cancers fit in review paper models, namely the very early, the very low and the mucinous; and third, the key clinical tumour features may be tricky to analyse. In this review, we discuss the normal anatomy of the rectum and posterior compartment of the pelvis, systematise all rectal cancer staging key points and elaborate on the particularities of early, low and mucinous tumours. We also include our suggested reporting templates and a discussion of its comparison to the reporting templates provided by ESGAR and SAR.

Higher-order diffusion MRI characterization of mesorectal lymph nodes in rectal cancer

PURPOSE

Mesorectal lymph node staging plays an important role in treatment decision making. Here, we explore the benefit of higher-order diffusion MRI models accounting for non-Gaussian diffusion effects to classify mesorectal lymph nodes both 1) ex vivo at ultrahigh field correlated with histology and 2) in vivo in a clinical scanner upon patient staging.

METHODS

The preclinical investigation included 54 mesorectal lymph nodes, which were scanned at 16.4 T with an extensive diffusion MRI acquisition. Eight diffusion models were compared in terms of goodness of fit, lymph node classification ability, and histology correlation. In the clinical part of this study, 10 rectal cancer patients were scanned with diffusion MRI at 1.5 T, and 72 lymph nodes were analyzed with Apparent Diffusion Coefficient (ADC), Intravoxel Incoherent Motion (IVIM), Kurtosis, and IVIM-Kurtosis.

RESULTS

Compartment models including restricted and anisotropic diffusion improved the preclinical data fit, as well as the lymph node classification, compared to standard ADC. The comparison with histology revealed only moderate correlations, and the highest values were observed between diffusion anisotropy metrics and cell area fraction. In the clinical study, the diffusivity from IVIM-Kurtosis was the only metric showing significant differences between benign (0.80 ± 0.30 μm² /ms) and malignant (1.02 ± 0.41 μm² /ms, P = .03) nodes. IVIM-Kurtosis also yielded the largest area under the receiver operating characteristic curve (0.73) and significantly improved the node differentiation when added to the standard visual analysis by experts based on T₂ -weighted imaging.

CONCLUSION

Higher-order diffusion MRI models perform better than standard ADC and may be of added value for mesorectal lymph node classification in rectal cancer patients.

Pathological Tumor Regression Grade Classifications in Gastrointestinal Cancers: Role on Patients' Prognosis

Preoperative chemotherapy or combined radiotherapy and chemotherapy (CRT), followed by surgery, represents the standard approach for locally advanced esophageal, gastric, and rectal carcinomas. To adequately evaluate the effects of neoadjuvant CRT in the resection specimens, several histopathologic tumor regression grade (TRG) scoring systems have been introduced into clinical practice. The primary goal of these TRG systems relies on a correct prognostic stratification of patients in the attempt to help clinical decision-making and influence surgical strategies, postoperative adjuvant therapies, and surveillance intensity. However, most TRG systems suffer from poor reproducibility and low interobserver concordance rates. Many efforts have been made in the identification of alternative, robust, simple, and universally accepted TRG scoring systems, which would help in the comparison of different treatment strategies and in the standardization of multimodal therapies. The aim of this review is to analyze the most commonly used TRG systems in gastrointestinal cancers highlighting their pitfalls and usefulness, depending on the tumor type.

Fat clearance and conventional fixation identified ypN0 rectal cancers following intermediate neoadjuvant radiotherapy have similar long-term outcomes

BACKGROUND

As a prognostic factor for colorectal cancer, lymph node (LN) status, particularly the number of LN harvested, has been demonstrated to be essential in the evaluation of quality control in terms of surgical specimen. Neoadjuvant chemoradiation, however, decreases the LN harvest. Therefore, certain approaches (such as fat clearance or methylene blue) has drawn significant attention in order to raise LN yield.

AIM

To compare the long-term oncologic outcome of ypN0 rectal cancer identified using fat clearance (FC) or conventional fixation (CF) following 30 Gy in 10 fractions (30 Gy/10f) of neoadjuvant radiotherapy (nRT).

METHODS

Three hundred and eighty-two patients with resectable and locally advanced rectal cancer were treated by 30 Gy/10f intermediate nRT (biologically equivalent dose of 36 Gy) plus total mesorectal excision. Two specimen fixation methods (FC or CF) were non-randomly used. The ypN0 status was identified in 124 and 101 patients in the FL and CF groups, respectively. Primary endpoints were local recurrence-free survival (LRFS) and cancer-specific survival (CSS).

RESULTS

The median follow-up of patients was 5.1 years. The median numbers of retrieved LNs in the FC and CF groups were 19.5 (range, 4-47) and 12 (range, 0-44), respectively, with a significant difference (P = 0.000). The percentages of patients with 12 or more retrieved nodes were 82.3% and 50.5% (101/159) in the FC and CF groups, respectively, with a significant difference (P = 0.000). The LRFS at 5 years were 95.7% and 94.6% in the FC and CF groups, respectively, without statistical difference (P = 0.819). The CSS at 5 years were 92.0% and 87.2% in the FC and CF groups, respectively, without statistical difference (P = 0.482).

CONCLUSION

For patients with ypN0 rectal cancer who underwent 30 Gy/10f preoperative radiotherapy, the increased retrieval of LNs using fat clearance is not associated with survival benefit. This time-consuming fixation method has a low efficacy as a routine practice.

Susceptibility Perturbation MRI Maps Tumor Infiltration into Mesorectal Lymph Nodes

Noninvasive characterization of lymph node involvement in cancer is an enduring onerous challenge. In rectal cancer, pathologic lymph node status constitutes the most important determinant of local recurrence and overall survival, and patients with involved lymph nodes may benefit from preoperative chemo and/or radiotherapy. However, knowledge of lymph node status before surgery is currently hampered by limited imaging accuracy. Here, we introduce Susceptibility-Perturbation MRI (SPI) as a novel source of contrast to map malignant infiltration into mesorectal lymph nodes. SPI involves multigradient echo (MGE) signal decays presenting a nonmonoexponential nature, which we show is sensitive to the underlying microstructure via susceptibility perturbations. Using numerical simulations, we predicted that the large cell morphology and the high cellularity of tumor within affected mesorectal lymph nodes would induce signature SPI decays. We validated this prediction in mesorectal lymph nodes excised from total mesorectal excision specimens of patients with rectal cancer using ultrahigh field (16.4 T) MRI. SPI signals distinguished benign from malignant nodal tissue, both qualitatively and quantitatively, and our histologic analyses confirmed cellularity and cell size were the likely underlying sources for the differences observed. SPI was then adapted to a clinical 1.5 T scanner, added to patients' staging protocol, and compared with conventional assessment by two expert radiologists. Nonmonoexponential decays, similar to those observed in the ex vivo study, were demonstrated, and SPI classified lymph nodes more accurately than standard high-resolution T₂-weighted imaging assessment. These findings suggest this simple, yet highly informative, method can improve rectal cancer patient selection for neoadjuvant therapy. SIGNIFICANCE: These findings introduce an MRI methodology tailored to detect magnetic susceptibility perturbations induced by subtle alterations in tissue microstructure.

Pathological nodal staging score for rectal cancer patients treated with radical surgery with or without neoadjuvant therapy: a postoperative decision tool

Background

Lymph node status can predict the prognosis of patients with rectal cancer treated with surgery. Thus, we sought to establish a standard for the minimum number of lymph nodes (LNs) examined in patients with rectal cancer by evaluating the probability that pathologically negative LNs prove positive during surgery.

Patients and methods

We extracted information of 31,853 patients with stage I–III rectal carcinoma registered between 2004 and 2013 from the Surveillance, Epidemiology, and End Results database and divided them into two groups: the first group was SURG, including patients receiving surgery directly and the other group was NEO, encompassing those underwent neo-adjuvant therapy. Using a beta-binomial model, we developed nodal staging score (NSS) based on pT/ypT stage and the number of LNs retrieved.

Results

In both cohorts, the false-negative rate was estimated to be 16% when 12 LNs were examined, but it dropped to 10% when 20 LNs were evaluated. In the SURG cohort, to rule out 90% possibility of false staging, 3, 7, 28, and 32 LNs would be necessarily examined in patients with pT1–4 disease, respectively. While in the NEO cohort, 4, 7, 12, and 16 LNs would be included for examination in patients with ypT1–4 disease to guarantee an NSS of 90%.

Conclusion

By determining whether a rectal cancer patient with negative LNs was appropriately staged, the NSS model we developed in this study may assist in tailoring postoperative management.

Lymph node ratio as a valuable prognostic factor for patients with colorectal liver-only metastasis undergoing curative resection

Background

Recent studies have suggested that the lymph node ratio (LNR) is a prognostic indicator for various malignancies. However, LNR has not been evaluated in colorectal liver-only metastasis (CRLM). This study aimed to investigate the prognostic value of LNR in patients with CRLM after curative resection.

Patients and methods

We retrospectively investigated the clinicopathologic features of 154 CRLM patients who underwent curative resection between 2005 and 2015. We classified patients into low and high groups based on their LNR by using the X-tile software. Survival curves were plotted through Kaplan–Meier method and compared by log-rank test. Cox proportional hazards analysis was performed to identify the factors associated with recurrence-free survival (RFS) and overall survival (OS).

Results

The patients were divided into two groups in which 124 patients were identified as LNR ≤0.33 and 30 patients as LNR >0.33. Compared to low LNR, high LNR was significantly associated with poor 3-year RFS (47.2% vs 16.7%, P=0.001) and OS (72.8% vs 45.3%, P=0.003) rates. Multivariate analysis indicated that the LNR was an independent predictor for 3-year RFS (hazard ratio, 2.124; 95% CI, 1.339–3.368; P=0.001) and OS (HR, 2.287; 95% CI, 1.282–4.079; P=0.005). However, the node (N) stage and lymph node distribution were not significantly associated with the 3-year RFS (P=0.071, P=0.226) or OS (P=0.452, P=0.791) in patients with CRLM.

Conclusion

This study demonstrated that LNR was an independent predictor for 3-year RFS and OS in patients with CRLM who underwent curative resection and that its prognostic value was superior to that of N stage and lymph node distribution.

Pathologic assessment of gastrointestinal tract and pancreatic carcinoma after neoadjuvant therapy

Neoadjuvant therapy is increasingly used to treat patients with a wide variety of malignancies. Histologic evaluation of treated specimens provides important prognostic information and may guide subsequent chemotherapy. Neoadjuvant therapy is commonly employed in the treatment of locally advanced rectal adenocarcinoma, hepatic colorectal metastases, esophageal/esophagogastric junction carcinoma, and pancreatic ductal adenocarcinoma. Numerous tumor regression schemes have been used in these tumors and standardized approaches to evaluate these specimens are needed. In this review, the various tumor regression scoring systems that have been used in these organs are described and their associations with clinical outcomes are discussed. Recommendations regarding how to handle and report the histologic findings in these resections specimens are provided.

A modified sentinel lymph node technique combined with endoluminal loco-regional resection for the treatment of rectal tumours: a 14-year experience

AIM

After endoluminal loco-regional resection (ELRR) by transanal endoscopic microsurgey (TEM) the N parameter may remain undefined. Nucleotide-guided mesorectal excision (NGME) improves the lymph node harvest. The aim of the present study is to evaluate the long-term oncological results after ELRR with NGME.

METHOD

A total of 57 patients were enrolled over the period January 2001 to June 2015. All patients underwent ELRR by TEM. Prior to surgery, 99 m-technetium-marked nanocolloid was injected into the peritumoural submucosa. After removal of the specimen, the residual defect was probed to detect any residual radioactivity and 'hot' mesorectal fat was excised. All patients were included in a 5-year follow-up programme.

RESULTS

Significant radioactivity in the residual cavity was found in 28 out of 57 patients (49%). The mean number of lymph nodes harvest in irradiated and nonirradiated patients was 1.66 and 2.76, respectively. After 68.2 months' follow-up overall survival was 91.2%, disease-related mortality 3.5% and disease-free survival 89.5%. Two patients developed pulmonary metastases: one ypT3N0 patient underwent lung lobectomy after chemotherapy and one pT2N0 patient was managed with lung radiotherapy. Both patients are currently alive and disease-free at 48 months' follow-up. Two patients developed local recurrence 1 year after ELRR, both treated with neoadjuvant chemo-radiotherapy and total mesorectal excision. Comparing the present series with previous patients who did not undergo NGME, an increased number of harvested lymph nodes were observed, with a statistically significant difference (P = 0.0085).

CONCLUSION

NGME during ELRR improves the lymph node harvest and staging accuracy. The long-term results showed satisfactory local (3.5%) and distant (7%) recurrence rates.

Prognostic impact of lymph node skip metastasis in Stage III colorectal cancer

AIM

The aim of this study was to evaluate the prognostic impact of lymph node skip metastasis (LNSM) in patients with Stage III colorectal cancer.

METHOD

Between April 2003 and December 2014, a total of 41 patients with lymph node skip metastasis (skip+) were compared with 86 patients with pericolic lymph node metastases [lymph node distribution (LND)1] and 57 patients with intermediate and/or main lymph node metastasis (LND2+3). All patients had radical D3 lymphadenectomy, performed either laparoscopically or as open surgery.

RESULTS

The frequency of pT1-2 stage cancer was significantly higher in the skip+ group than in the LND1 group (26.8% vs 5.8%, P = 0.001). The number of metastatic lymph nodes in the skip+ group was lower than in the LND2+3 group (1.9 ± 1.5 vs 6.5 ± 6.0, P < 0.001). The 3-year disease-free survival (DFS) of the skip+, LND1 and LND2+3 groups was 64.8%, 69.7% and 40.1%, respectively (P = 0.008). The 3-year systemic recurrence rates of the skip+, LND1 and LND2+3 groups were 30.2%, 20.3% and 48.1%, respectively; (P = 0.002). Cox regression analysis revealed that preoperative carcinoembryonic antigen (CEA) of ≥ 5 ng/ml [hazard ratio (HR) = 2.2, P = 0.029], poor differentiation (HR = 3.8, P = 0.001) and skip+ (HR = 0.2, P = 0.021) were independently prognostic factors for DFS.

CONCLUSION

The prognosis for the LND1-negative lymph node skip metastasis group was better than for the LND2+3 group and was comparable with that of the LND1 group after radical D3 lymphadenectomy.

The prognostic value of lymph node ratio in a national cohort of rectal cancer patients

OBJECTIVE

To analyze the prognostic implications of the lymph node ratio (LNR) in curative resected rectal cancer.

SUMMARY BACKGROUND DATA

It has been proposed that the LNR has a high prognostic impact in colorectal cancer, but the lymph node ratio has not been evaluated exclusively for rectal cancer in a large national cohort study.

METHODS

All 6793 patients in Denmark diagnosed with stage I to III adenocarcinoma of the rectum, and so treated in the period from 2003 to 2011, were included in the analysis. The cohort was divided into two groups according to whether or not neo-adjuvant treatment had been given.

RESULTS

In a multivariate analysis the pN status, ypN status and lymph node yield were found to be independent prognostic factors for overall survival, irrespective of neo-adjuvant therapy. The LNR was also found to be a significant prognostic factor with a Hazard Ratio ranging from 1.154 (95% CI: 0.930-1.432) (LNR: 0.01-0.08) to 2.974 (95% CI: 2.452-3.606) (LNR > 0.5) in the group of patients who had surgery to begin with and from 1.381 (95% CI: 0.891-2.139) (LNR: 0.01-0.08) to 2.915 (95% CI: 2.244-3.787) (LNR > 0.5) in the group of patients who had neo-adjuvant treatment.

CONCLUSIONS

The LNR reflects the influence on survival from N-status and the lymph node yield and since LNR was shown to be a significant prognostic predictor for overall survival in patients with curatively resected stage III rectal cancer irrespective of neo-adjuvant therapy we recommend that the introduction of LNR should be considered for rectal cancer in a revised TNM classification.

Size and distribution of lymph nodes in rectal cancer resection specimens

BACKGROUND

The detection of lymph node involvement is fundamental to the staging of rectal cancer, and aids in prognostication and identification of patients who will benefit from adjuvant therapy. The anatomical variation in distribution and size of mesorectal lymph nodes has received scant attention.

OBJECTIVE

This study aimed to determine the size and distribution of lymph nodes in rectal cancer resection specimens.

DESIGN

This was a prospective, observational study of rectal cancer resection specimens analyzed by a single histopathologist.

SETTING

This study was conducted from January 2007 to July 2013 at the authors' institution.

PATIENTS

Two hundred forty-four consecutive patients underwent resection for rectal cancer.

MAIN OUTCOME MEASURES

The size and distribution of lymph nodes in the resection specimens and the anatomical position of mesorectal lymph nodes in relation to the peritoneal reflection, tumor, and anal verge were recorded.

RESULTS

A total of 10,473 lymph nodes were retrieved in 244 patients (75 women; median age, 68 years (interquartile range, 59-75 years)). One hundred seventy-three anterior resection and 71 abdominoperineal resection specimens were analyzed. Median lymph node yield was 41 lymph nodes (interquartile range, 31-52); 344 of 10,473 (3.2%) lymph nodes were positive. Lymph nodes were distributed in the mesorectum, sigmoid mesentery, and vascular pedicle in 40%, 32%, and 28% of the patients. Sixty-eight percent of mesorectal lymph nodes were above the peritoneal reflection. Mesorectal lymph node distribution in relation to the tumor was 53% above, 36% adjacent to, and only 11% below the tumor. Ninety-five of 334 (28%) positive nodes were ≤3 mm in diameter.

LIMITATIONS

Resection specimens analyzed by other pathologists (<5%) have not been included, and fat clearance techniques were not used to retrieve lymph nodes.

CONCLUSIONS

To ensure accurate nodal staging of rectal cancer, both resection and subsequent pathological evaluation should focus on the mesorectum in close proximity to the tumor and along the superior rectal artery. Small lymph nodes (<3 mm in size) should not be overlooked, and lymph node metastasis to the sigmoid mesentery is rare (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A177).

A minimum yield of twelve lymph nodes in rectal cancer remains valid in the era of neo-adjuvant treatment : results from a national cohort study

PURPOSE

The purpose of the study was to examine if a minimum of 12 lymph nodes (LNs) is still valid in rectal cancer after neo-adjuvant treatment.

METHODS

An analysis was carried out in a nationwide Danish cohort of 6793 patients, treated by curative resection of stage I-III rectal cancer during the period 2003-2011. The cohort was divided into two groups according to whether neo-adjuvant treatment had been given. The groups were analysed separately and were further analysed according to four lymph node yield (LNY) groups 0-5, 6-11, 12-17 and ≥18.

RESULTS

Two thousand one hundred twenty-three patients (31.0 %) received neo-adjuvant treatment. A median LNY of 10 and 15 (p < 0.0001) and rates of node-positive (N-positive) disease of 31.6 and 36.7 % (p < 0.001) were observed with and without (+/-) neo-adjuvant treatment, respectively. The rate of N-positive disease according to tumour stage ranged from 4.8 %/11.4 % (ypT0/pT1) to 42.1 %/64.1 % (ypT4/pT4). The rate of N-positive disease according to LNY ranged from 19.5 %/16.8 % (0-5 LNs) to 42.6 %/37.9 % (≥18 LNs) (-/+neo-adjuvant treatment). In a logistic regression analysis, a significant association was found between N-positive disease and pT/ypT stage as well as between N-positive disease and LNY.

CONCLUSIONS

A significantly smaller ratio of N-positive disease was observed in the group of patients who had received neo-adjuvant treatment. The ratio of N-positive disease increased significantly with more advanced tumour stage and increasing LNY irrespective of neo-adjuvant treatment. A minimum of 12 LNs is needed to ensure N-negative disease, irrespective of neo-adjuvant treatment.

Prognostic implications of the lymph node count after neoadjuvant treatment for rectal cancer

BACKGROUND

The aim of this study was to investigate the effect of neoadjuvant chemoradiotherapy on the lymph node yield of rectal cancer surgery.

METHODS

Data for patients who underwent neoadjuvant chemoradiotherapy followed by surgery for resectable rectal cancer from June 1992 to June 2009 were reviewed. The primary outcomes measured were the number of lymph nodes retrieved, their status, and patient survival.

RESULTS

In total, 345 patients underwent neoadjuvant chemoradiotherapy followed by surgery, and 95 patients had surgery alone. Neoadjuvant chemoradiotherapy decreased both the median (range) number of lymph nodes retrieved (7 (1-33) versus 12.5 (0-44) respectively; P < 0.001) and the number of positive lymph nodes (0 (0-11) versus 0 (0-16); P = 0.001). After neoadjuvant chemoradiotherapy, the number of retrieved lymph nodes was inversely correlated with tumour regression, and with the interval between treatment and surgery. The 5-year overall and disease-free survival rates were 86.5 and 79.1 per cent respectively. After neoadjuvant therapy, lymph node status was found to be an independent predictor of survival, whereas the number of retrieved lymph nodes did not represent a prognostic factor for either overall or disease-free survival.

CONCLUSION

Low lymph node count after neoadjuvant chemoradiotherapy for rectal cancer does not signify an inadequate resection or understaging, but represents an increased sensitivity to the treatment.

Transanal endoscopic microsurgery combined with endoscopic posterior mesorectum resection in the treatment of patients with T1 rectal cancer - 3-year results

Introduction

Rectum-sparing transanal endoscopic microsurgery (TEM) is a well-established treatment for T1 rectal cancer (RC). However, it is associated with an increased rate of local recurrence in comparison with extended resection. In most cases this failure is linked to inappropriate case selection and the presence of clinically non-detectable metastases in the regional lymph nodes. Endoscopic posterior mesorectal resection (EPMR) makes it possible to remove the relevant lymphatic drainage of the lower third of the rectum in a minimally invasive way, which in turn can help in adequate tumor staging.

Aim

To evaluate the long-term clinical results and influence of combined TEM and EPMR treatment on the anorectal functions.

Material and methods

Ten consecutive patients with T1 RC were operated on using TEM and EPMR as a two-stage procedure between 2007 and 2009.

Results

After a median follow-up of 42.6 (range: 36–80) months, none of our patients complained of symptoms of incontinence apart from one female patient with gas incontinence diagnosed preoperatively. There was no statistically significant difference in basal anal pressure, squeeze anal pressure, high pressure zone length or fecal continence assessed using the Fecal Incontinence Severity Index before and in follow-up months after the procedure. Postoperative morbidity consisted of one hematoma formation and one male patient complaining about sexual dysfunction until 6 months postoperatively. There was no evidence of locoregional recurrence.

Conclusions

Endoscopic posterior mesorectal resection in combination with TEM appears to be safe, feasible and with no impact on the basic anorectal functions in the 3-year follow-up.

Distal dissection in total mesorectal excision, and preoperative chemoradiotherapy and lateral lymph node dissection for rectal cancer

The local recurrence rate after total mesorectal excision (TME) appears to be markedly lower than that after conventional operations. We reviewed all relevant articles identified from the MEDLINE databases and clarified the rationale for TME. It is clear that distal intramural spread is rare. Even when present, such spread is not likely to extend beyond 2 cm. Data with attention to mesorectal cancer deposits suggest that mesorectal clearance of at least 4-5 cm distal to the tumor should be sufficient. TME should be performed for most tumors of the mid- and lower rectum. This does not mean that the gut tube needs to be divided at the same level in every case. Dissection of the distal mesorectum off the gut tube can be performed, so the distal line of division of the bowel wall can be made at a minimum of 2 cm below the tumor if such a maneuver would ensure that the sphincters are preserved. In cases with cancer in the upper third of the rectum, the mesorectum and gut tube can safely be divided 5 cm below the tumor without jeopardizing the recurrence rates. Our findings indicate that TME is an essential treatment approach for rectal cancer, and lateral lymph node dissection and preoperative chemoradiotherapy are additional therapies that should be considered for advanced rectal cancer.

In vivo lymph node mapping and pattern of metastasis spread in locally advanced mid/low rectal cancer after neoadjuvant chemoradiotherapy

PURPOSE

The lymph node status is one of the strongest prognostic determinants in rectal cancers. After chemoradiotherapy (CRT), lymph nodes are difficult to detect. This study aims to evaluate the feasibility of lymph node mapping in the mesorectum after CRT to analyze the pattern of metastasis spread and to assess the reliability of blue dye injection in sentinel lymph node detection.

METHOD

Ten patients with cN+ mid/low RCs after CRT were prospectively enrolled. The protocol scheduled intraoperative blue dye injection, surgery, and specimen examination with fat clearance technique. The mesorectum was divided into three equal "levels" (upper, middle, and lower); each level was divided into three equal "sectors" (right anterolateral, posterior, and left anterolateral). Lymph nodes were defined "small" if ≤5 mm.

RESULTS

Two hundred seventy-six lymph nodes were retrieved in ten patients; 76.5 % were small lymph nodes. Six patients were pN+ (33 metastatic lymph nodes, 76 % small); small lymph node analysis upstaged one patient from N0 to N1 and four patients from N1 to N2. Metastasis distribution across sectors was continuous, without "skip sectors." The blue dye detected the sentinel lymph node in all patients; in half of the cases, it was out of the tumor sector. Blue dye identified 69.7 % of metastatic lymph nodes; its sensitivity decreased together with the metastatic deposit size (84 % macrometastases, 28.6 % micrometastases, 0 % occult tumor cells; p = 0.004).

CONCLUSION

The fat clearance technique should be the standard pathological examination in patients with RCs after CRT; N staging was improved by small lymph node identification. Lymph node metastases have a continuous spread through mesorectal sectors. Blue dye injection is effective in sentinel lymph node detection.

Value of transrectal ultrasonography for tumor node metastasis restaging in patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy

OBJECTIVE

To explore the value of transrectal ultrasonography (TRUS) for tumor node metastasis (TNM) restaging for patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy (neo-CRT).

METHODS

One hundred and forty-nine patients with locally advanced rectal cancer (cT3-4 or cN+) who underwent TRUS after neo-CRT were retrospectively reviewed. TRUS restaging was compared with the results of post-operative pathological TNM findings.

RESULTS

After neo-CRT, the accuracy of TRUS for diagnosing T-staging was 30.9%, with 60.4% (90/149) of cases overestimated. The sensitivity of TRUS for T-staging (T0 vs T1 vs T2 vs T3 vs T4) were 16.3%, 0%, 12.5%, 42.6% and 75.0%, respectively. The accuracy of TRUS for diagnosing N-staging after neo-CRT was 81.2%, with the sensitivities of N0 and N+ were 93.3% and 31.0%, respectively. After neo-CRT, 27.5% (41/149) of patients achieved pathologically complete response (pCR). The sensitivity, specificity, positive predictive value and negative predictive values of TRUS for pCR were 17.1%, 99.1%, 87.5% and 75.9%, respectively.

CONCLUSIONS

TRUS can be applied for restaging T4 and N0, and has potential for screening out patients with pCR in those with locally advanced rectal cancer after neo-CRT, although some stages are overestimated for T-staging and its sensitivity for predicting pCR is low.

Clinical impact of fat clearing technique in nodal staging of rectal cancer after preoperative chemoradiotherapy

Purpose

This study was designed to evaluate the efficacy of a fat clearing technique for accurate nodal staging of rectal cancer patients after preoperative chemoradiotherapy (CRT).

Methods

A total of 19 patients with rectal cancer within 10 cm from anal verge were divided into two groups: non-CRT group (n = 10) and CRT group (n = 9). For pathologic assessment, lymph node (LN) harvest was performed using conventional manual dissection followed by a fat clearing technique.

Results

A median of 3.0 additional LNs in non-CRT group and 3.8 LNs in CRT group were identified by the fat clearing technique. When subanalysis was performed in patients with fewer than 12 retrieved LNs, a median of 4.0 extra LNs in non-CRT group and 3.5 extra LNs in CRT group were identified after the fat clearing technique. None of additionally identified nodes were metastatic. In both groups, the median size of retrieved LNs following the fat clearing technique was smaller than that obtained by manual dissection (2.0 mm vs. 3.0 mm, P < 0.001).

Conclusion

The fat clearing technique allowed detection of additional LNs that were missed by the manual method, but these detected LNs were not proven to be metastatic.