Indications for Lateral Pelvic Lymph Node Dissection Based on Magnetic Resonance Imaging Before and After Preoperative Chemoradiotherapy in Patients with Advanced Low-Rectal Cancer

Positive lateral lymph node turned negative after neoadjuvant therapy-surgery or observation?

Since the adoption of neoadjuvant chemoradiation and total mesorectal excision as the standard in rectal cancer care, there has been marked improvement in the local recurrence rates. In this context, restaging magnetic resonance imaging (MRI) plays a key role in the assessment of tumor response, occasionally enabling organ-sparing approaches. However, the role of restaging MRI in evaluating lateral lymph nodes remains limited. Most studies suggest a high risk of lateral local recurrence regardless of a decrease in lymph node size on restaging MRI. Therefore, it is recommended that clinical decisions should rely on the primary MRI scan. Watchful waiting may be appropriate only in cases of a clinical complete response with substantial downsizing of lateral lymph nodes (≤ 4.0 mm). Notably, some lateral lymph nodes may enlarge during follow-up despite complete tumor response, in which case, lateral lymph node dissection can be considered while preserving the rectum. Thus, continuous surveillance of lateral lymph nodes is essential during watchful waiting. Restaging MRI may hold greater importance for smaller lymph nodes (5.0-6.9 mm), as those with persistent malignant features on imaging carry a 13% risk of lateral recurrence at 4 years. Understanding these risks is critical when engaging in shared decision-making with the patient.

Who is a candidate at the initial presentation? Prediction of positive lateral lymph node and survival after dissection

Metastatic lateral pelvic lymph node (LPN) in rectal cancer has a significant clinical impact on the prognosis and treatment strategies. But there are still debates regarding prediction of lateral pelvic lymph node metastasis and its oncological impact. This review explores the evidence for predicting lateral pelvic lymph node metastasis and survival in locally advanced rectal cancer. Until now many studies have reported that magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) are considered as essential tools for predicting metastatic LPN, with MRI-based size criteria, particularly the short-axis diameter of LPN. But several studies have reported that the addition of tumor location or artificial intelligence (AI) can further enhance diagnostic accuracy. Western practices focus more on neoadjuvant chemoradiation (nCRT), while Eastern countries focus more on lateral pelvic lymph node dissection (LPND). LPND has been shown to reduce lateral local recurrence (LLR) rates compared to total mesorectal excision (TME) alone, particularly in patients with enlarged LPNs, but its impact on overall survival is uncertain. The decision to perform LPND should be individualized according to LPN size and response to nCRT; and through selective LPND based on those criteria, patients could achieve a balance between the benefit of local control and the risk of surgical complications from LPND, such as sexual and urinary dysfunction.

Lateral pelvic lymph nodes dissection of rectal neuroendocrine neoplasms: A prospective case-series and literature review

BACKGROUND

Rectal neuroendocrine neoplasms are relatively rare. Patients with rectal neuroendocrine neoplasms undergoing radical surgery have a higher rate of lymph node metastases. Robust evidence on the status of lateral pelvic lymph node metastases and the role of lateral pelvic lymph node dissection in those patients is lacking. This case-series study aimed to explore and address these issues.

METHODS

This single-center, prospective case series consecutively enrolled patients with biopsy-proven rectal neuroendocrine neoplasms in a tertiary referral hospital between June 2022 and January 2024. All eligible patients underwent laparoscopic total mesorectal excision surgery and bilateral lateral pelvic lymph node dissection under general anesthesia. The clinicopathologic features, surgical outcomes, and postoperative complications were presented. The last follow-up was conducted in March 2024.

RESULTS

A total of 11 patients with rectal neuroendocrine neoplasms-3 female and 8 male-were enrolled. The average age was 60.0 years (range, 53.5-65.5 years), and the median tumor size was 2.0 cm (range, 1.6-2.5 cm). Tumors invaded the muscularis propria in 7 patients. There were 3 cases of neuroendocrine tumor G1, 6 cases of neuroendocrine tumor G2, and 2 cases of neuroendocrine carcinoma. Among these patients, 11 (100.0%) had lymph node metastases, and 6 (54.5%) had lateral pelvic lymph node metastases. In addition, in 2 patients, only lateral pelvic lymph node metastases were observed, without involvement of the mesenteric lymph nodes. Five patients had tumors located on the left wall of the rectum, and only left-sided lateral pelvic lymph node metastases were observed. The other patient had both sides of lateral pelvic lymph node metastases due to circumferential growth of the tumor around the rectum. Anal preservation was achieved in all patients. The median operating time was 235.0 minutes (range, 210.5-335.5 minutes), and the median estimated blood loss was 50.0 mL (range, 45.0-75.0 mL). Two patients experienced postoperative dysuria and recovered spontaneously within 2-4 months after surgery.

CONCLUSION

On the basis of a prospective case series, we demonstrate, for the first time, the lateral pelvic lymph node metastasis status in patients with rectal neuroendocrine neoplasms requiring radical total mesorectal excision surgery. Simultaneous bilateral lateral pelvic lymph node dissection may be a feasible and beneficial procedure for preventing local recurrence in these patients due to the lack of definitive neoadjuvant or adjuvant therapy options.

Optimised treatment of patients with enlarged lateral lymph nodes in rectal cancer: protocol of an international, multicentre, prospective registration study after extensive multidisciplinary training (LaNoReC)

INTRODUCTION

Inadequate treatment of enlarged lateral lymph nodes (LLNs) in rectal cancer patients is associated with an increased lateral local recurrence (LLR) risk, despite neoadjuvant treatment and total mesorectal excision (TME) surgery. There is a promising role for LLN dissection (LLND) to lower this risk, but this challenging procedure requires appropriate training. This study protocol describes a prospective evaluation of oncological outcomes after standardised treatment based on multidisciplinary training, thereby aiming for a 50% reduction in LLR rate.

METHODS AND ANALYSIS

A prospective registration study will be opened in hospitals in which the involved multidisciplinary team members (radiologists, radiation oncologists, surgeons and pathologists) have received dedicated training to enhance knowledge and awareness of LLNs and in which standardised treatment including LLND has been implemented. Patients with rectal cancer and at least one enlarged LLN (short-axis ≥7.0 mm), or intermediate LLN (short-axis 5.0-6.9 mm) with at least one malignant feature on primary MRI, evaluated by a trained radiologist, are eligible. Patients will undergo neoadjuvant treatment by trained radiation oncologists, followed by TME surgery in combination with a minimally invasive, nerve-sparing LLND performed by trained surgeons. LLND specimens are evaluated by trained pathologists or grossing assistants. The primary outcome is LLR rate 3 years postoperatively. Secondary outcomes are morbidity, disease-free survival, overall survival and quality of life. To demonstrate a significant reduction in LLR rate from 13% (based on historical control data) to 6% after optimised treatment, 200 patients with enlarged LLNs are required.

ETHICS AND DISSEMINATION

The medical ethics board of the Vrije Universiteit Medical Centre (VUMC), the Netherlands, approved the study on 23 November 2022 (reference: 2021.0524). Participating centres must obtain local approval and participants are required to provide written informed consent. Results obtained from this study will be communicated via peer-reviewed medical journals and presentations at conferences.

TRAIL REGISTRATION NUMBER

NCT04486131, 24 July 2020, https://clinicaltrials.gov/ct2/show/NCT04486131.

The Learning Curve for Robotic Lateral Pelvic Lymph Node Dissection for Rectal Cancer: A View From the West

BACKGROUND

Lateral pelvic lymph node dissection is performed for selected patients with rectal cancer with persistent lateral nodal disease after neoadjuvant therapy. This technique has been slow to be adopted in the West because of concerns regarding technical difficulty. This is the first report on the learning curve for lateral pelvic lymph node dissection in the United States or Europe.

OBJECTIVE

This study aimed to analyze the learning curve associated with robotic lateral pelvic lymph node dissection.

DESIGN

Retrospective observational cohort.

SETTING

Tertiary academic cancer center.

PATIENTS

Consecutive patients from 2012 to 2021.

INTERVENTION

All patients underwent robotic lateral pelvic lymph node dissection.

MAIN OUTCOME MEASURES

The primary end points were the learning curves for the maximum number of nodes retrieved and urinary retention, which was evaluated with simple cumulative sum and 2-sided Bernoulli cumulative sum charts.

RESULTS

Fifty-four procedures were included. A single-surgeon learning curve (n = 35) and an institutional learning curve are presented in the analysis. In the single-surgeon learning curve, a turning point marking the end of a learning phase was detected at the 12th procedure for the number of retrieved nodes and at the 20th procedure for urinary retention. In the institutional learning curve analysis, 2 turning points were identified at the 13th procedure, indicating progressive improvements for the number of retrieved nodes, and at the 27th procedure for urinary retention. No sustained alarm signals were detected at any time point.

LIMITATIONS

The retrospective nature, small sample size, and the referral center nature of the reporting institution may limit generalizability.

CONCLUSIONS

In a setting of institutional experience with robotic colorectal surgery, including beyond total mesorectal excision resections, the learning curve for robotic lateral pelvic lymph node dissection is acceptably short. Our results demonstrate the feasibility of the acquisition of this technique in a controlled setting, with sufficient case volume and proctoring to optimize the learning curve. See Video Abstract.

LA CURVA DE APRENDIZAJE DE LA DISECCIN ROBTICA DE LOS GANGLIOS LINFTICOS PLVICOS LATERALES EN EL CNCER DE RECTO UNA VISIN DESDE OCCIDENTE

ANTECEDENTES:La disección lateral de los ganglios linfáticos pélvicos se realiza en pacientes seleccionados con cáncer de recto con enfermedad ganglionar lateral persistente tras el tratamiento neoadyuvante. La adopción de esta técnica en Occidente ha sido lenta debido a la preocupación por su dificultad técnica. Éste es el primer informe sobre la curva de aprendizaje de la disección de los ganglios linfáticos pélvicos laterales en EE.UU. o Europa.OBJETIVO:El objetivo de este estudio fue analizar la curva de aprendizaje asociada a la disección robótica de los ganglios linfáticos pélvicos laterales.DISEÑO:Cohorte observacional retrospectiva.LUGAR:Centro oncológico académico terciario.PACIENTES:Pacientes consecutivos desde 2012 al 2021.INTERVENCIÓN:Todos los pacientes fueron sometieron a disección robótica de ganglios linfáticos pélvicos laterales.PRINCIPALES MEDIDAS DE RESULTADO:Los criterios de valoración primarios fueron las curvas de aprendizaje tomando en cuenta el mayor número de ganglios recuperados y la retención urinaria que fueron evaluados con gráficos de suma acumulativa simple y de suma acumulativa de Bernoulli de dos caras.RESULTADOS:Fueron incluidos 54 procedimientos. En el análisis se presentan una curva de aprendizaje de un solo cirujano (n = 35) y una curva de aprendizaje institucional. En la curva de aprendizaje de un solo cirujano, se detectó un punto de inflexión que marcaba el final de una fase de aprendizaje en el duodécimo procedimiento para el número de ganglios extraídos y en el vigésimo para la retención urinaria. En el análisis de la curva de aprendizaje institucional, se identificaron dos puntos de inflexión en las intervenciones 13.ª y 26.ª, que indicaron mejoras progresivas en el número de ganglios extraídos, y en la 27.ª en la retención urinaria. No se detectaron señales de alarma sostenidas en ningún momento.LIMITACIONES:La naturaleza retrospectiva, el pequeño tamaño de la muestra y la naturaleza de centro de referencia de la institución informante que pueden limitar la capacidad de generalizarse.CONCLUSIONES:En un entorno de experiencia institucional con cirugía robótica colorrectal incluyendo más allá de las resecciones TME, la curva de aprendizaje para la disección robótica de ganglios linfáticos pélvicos laterales es aceptablemente corta. Nuestros resultados demuestran la viabilidad de la adquisición de esta técnica en un entorno controlado, con un volumen de casos suficiente y una supervisión que puede optimizar la curva de aprendizaje. (Traducción-Dr. Osvaldo Gauto ).

Prediction of pathological response and lymph node metastasis after neoadjuvant therapy in rectal cancer through tumor and mesorectal MRI radiomic features

Establishing predictive models for the pathological response and lymph node metastasis in locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT) based on MRI radiomic features derived from the tumor and mesorectal compartment (MC). This study included 209 patients with LARC who underwent rectal MRI both before and after nCRT. The patients were divided into a training set (n = 146) and a test set (n = 63). Regions of interest (ROIs) for the tumor and MC were delineated on both pre- and post-nCRT MRI images. Radiomic features were extracted, and delta radiomic features were computed. The predictive endpoints were pathological complete response (pCR), pathological good response (pGR), and lymph node metastasis (LNM). Feature selection for various models involved sequentially removing features with a correlation coefficient > 0.9, and features with P-values ≥ 0.05 in univariate analysis, followed by LASSO regression on the remaining features. Logistic regression models were developed, and their performance was evaluated using the area under the receiver operating characteristic curve (AUC). Among the 209 LARC patients, the number of patients achieving pCR, pGR, and LNM were 44, 118, and 40, respectively. The optimal model for predicting each endpoint is the combined model that incorporates pre- and delta-radiomics features for both the tumor and MC. These models exhibited superior performance with AUC values of 0.874 (for pCR), 0.801 (for pGR), and 0.826 (for LNM), outperforming the MRI tumor regression grade (mrTRG) which yielded AUC values of 0.800, 0.715, and 0.603, respectively. The results demonstrate the potential utility of the tumor and MC radiomics features, in predicting treatment efficacy among LARC patients undergoing nCRT.

Lateral pelvic lymph node positivity (LPLNP) score: predictive clinic-radiological model of lateral pelvic lymph node involvement in rectal cancer patients

PURPOSE

The population in Western countries differs significantly from that in Eastern countries, and the prevalence of lateral pelvic lymph node (LPLN) involvement in Western populations remains largely unknown due to the limited application of LPLN dissection (LPLND). This discrepancy is primarily attributed to the higher body mass index commonly observed in Western populations, which increases the risk of intraoperative complications. Consequently, the aim of this study is to describe a specific Western clinico-radiological selection tool for LPLND, namely, the lateral pelvic lymph node positivity (LPLNP) score.

METHODS

This retrospective single center study was designed to elaborate the LPLNP score, which was further tested on a prospective cohort of patients. Clinical and MRI factors associated with LPLN involvement were identified, and logistic regression was used to establish the LPLNP score.

RESULTS

In the retrospective series, 120 patients underwent lateral pelvic lymph node dissection. After stepwise logistic regression, five parameters were ultimately included in the LPLNP score. When tested on 66 prospectively selected patients, 40 with an LPLNP score > 0.23 (corresponding to the highest sensitivity and specificity) underwent LPLND: 22 patients (55%) had pathologically confirmed positive LPLN. The negative predictive value of the LPLNP score was 96%, with a sensitivity of 95.7% and a specificity of 58.1%.

CONCLUSION

The LPLNP score was developed based on the largest group of Western patients with locally advanced rectal cancer. This scoring system demonstrated high sensitivity and specificity during validation on the prospective series, correctly identifying LPLN involvement in 55% of cases.

The role of lateral pelvic lymph node dissection in advanced rectal cancer: a review of current evidence and outcomes

Metastatic lateral pelvic lymph nodes (LPNs) in rectal cancer significantly impact the prognosis and treatment strategies. Western practices emphasize neoadjuvant chemoradiotherapy (CRT), whereas Eastern approaches often rely on LPN dissection (LPND). This review examines the evolving role of LPND in the context of modern treatments, including total neoadjuvant therapy (TNT), and the impact of CRT on the management of clinically suspicious LPNs. We comprehensively reviewed the key literature comparing the outcomes of LPND versus preoperative CRT for rectal cancer, focusing on recent advancements and ongoing debates. Key studies, including the JCOG0212 trial and recent multicenter trials, were analyzed to assess the efficacy of LPND, particularly in conjunction with preoperative CRT or TNT. Current evidence indicates that LPND can reduce local recurrence rates compared to total mesorectal excision alone in patients not receiving radiation therapy. However, the benefit of LPND in the context of neoadjuvant CRT is influenced by the size and pretreatment characteristics of LPNs. While CRT can effectively control smaller metastatic LPNs, larger or clinically suspicious LPNs may require LPND for optimal outcomes. Advances in surgical techniques, such as robotic-assisted LPND, offer potential benefits but also present challenges and complications. The role of TNT in controlling metastatic LPNs and improving patient outcomes is emerging but remains underexplored. The decision to perform LPND should be individualized based on patient-specific factors, including LPN size, response to neoadjuvant treatment, and surgeon expertise. Future research should focus on optimizing treatment protocols and further evaluating the role of TNT in managing metastatic LPNs.

Management of internal iliac and obturator lymph nodes in mid-low rectal cancer

In rectal cancer treatment, the diagnosis and management of lateral pelvic lymph nodes (LLN) are critical for preventing local recurrence. Over time, scholars have reached a consensus: when imaging suggests LLN metastasis, combining neoadjuvant chemoradiotherapy (nCRT) with selective LLN dissection (LLND) can mitigate the risk of recurrence. Selective LLND typically encompasses lymph nodes in the internal iliac and obturator regions. Recent studies emphasize distinctions between internal iliac and obturator lymph nodes regarding prognosis and treatment outcomes, prompting the need for differentiated diagnostic and treatment approaches.

Management of lateral pelvic lymph nodes in rectal cancer: Is it time to reach an Agreement?

In this editorial, we proceed to comment on the article by Chua et al, addressing the management of metastatic lateral pelvic lymph nodes (mLLN) in stage II/III rectal cancer patients below the peritoneal reflection. The treatment of this nodal area sparks significant controversy due to the strategic differences followed by Eastern and Western physicians, albeit with a higher degree of convergence in recent years. The dissection of lateral pelvic lymph nodes without neoadjuvant therapy is a standard practice in Eastern countries. In contrast, in the West, preference leans towards opting for neoadjuvant therapy with chemoradiotherapy or radiotherapy, that would cover the treatment of this area without the need to add the dissection of these nodes to the total mesorectal excision. In the presence of high-risk nodal characteristics for mLLN related to radiological imaging and lack of response to neoadjuvant therapy, the risk of lateral local recurrence increases, suggesting the appropriate selection of strategies to reduce the risk of recurrence in each patient profile. Despite the heterogeneous and retrospective nature of studies addressing this area, an international consensus is necessary to approach this clinical scenario uniformly.

The influence of neoadjuvant chemoradiotherapy combined with lateral lymph nodes dissection or not on the local recurrence of low to intermediate-stage II/III rectal cancer

BACKGROUND

Currently, the treatment options for stage II/III rectal cancer with preoperative lateral lymph nodes (LLN) enlargement are highly controversial between East and West, and the indications for diagnosing suspiciously positive enlarged LLN are inconsistent both nationally and internationally. Oriental scholars (especially Japanese) consider the LLN as a regional disease, they consider that prophylactic lateral lymph nodes dissection (LLND), regardless of whether the LLN is enlarged or not, is considered necessary if the tumor is found beneath the peritoneal reflex and invades the muscle layer. Western scholars regard LLN as distant metastases, recommending neoadjuvant chemoradiotherapy (nCRT) in conjunction with total rectal mesenteric resection (TME). In recent years, it has been found that neither of the two standard treatment regimens, East and West, significantly improved local control of tumors in patients with LLN enlargement. In contrast, nCRT combined with LLND significantly lowers the local recurrence (LR) rate. It has also been suggested that combination therapy regimens do not improve patient prognosis but increase treatment-related complications. Therefore, the suitable therapeutic option for rectal cancer with an enlarged LLN needs to be further explored.

AIM

Exploring appropriate treatment options for low to intermediate-stage II/III rectal cancer with LLN enlargement, as well as risk variables that may affect the LR in these patients with LLN enlarged.

METHODS AND PATIENTS

In this research, we retrospectively analyzed 110 patients with locally advanced mid-low (low boundary of tumor is no more than 10 cm from the anus) rectal cancer who were treated at Harbin Medical University Cancer Hospital arranged from 2017.1 to 2020.6. These patients had received nCRT and TME, and their initial rectal nuclear magnetic resonance imaging (MRI) revealed an enlarged LLN (short axis of LLN, SA ≥ 5 mm). Of these, 40 patients underwent LLND, thus, 110 patients were grouped into two groups: nCRT+TME (LLND-, n = 70) and nCRT+TME + LLND (LLND+, n = 40), and their 3 years prognoses were compared.

RESULTS

After a median follow-up of 49.0 months, the 3-year LR rate of the LLND- group was notably greater than the LLND+ group (22.8% vs. 7.5%, p = 0.04). However, there was no noteworthy difference in the 3-year progression-free survival (PFS, 70.5% vs. 77.5%, p > 0.05) rate or distant metastasis (DM) rate (20.0% vs. 17.5%, p > 0.05). Additionally, the LLND+ group experienced significantly more postoperative complications than the LLND- group (15.0% vs. 4.2%, p = 0.05). Subgroups analysis for the LLND- group revealed that patients with LLN short axis regression (ΔSA) > 35.9% after nCRT had significantly lower 3-year LR rate than patients with ΔSA ≤ 35.9% (9.1% vs. 35.1%, p = 0.01). Patients in the LLND- group with ΔSA > 35.9%, however, had comparable 3-year LR rate and DM rates to those in the LLND+ group.

CONCLUSION

LLN is an independent indicator for prognosis among people with low to intermediate-stage II/III malignant rectal tumors. Patients with poor SA regression (ΔSA ≤ 35.9%) after nCRT have a greater risk of positive LLN and a more substantial LR, and nCRT combined with LLND reduced the LR rate significantly, but considerably prolonged operative time, surgical bleeding, and postoperative complications. Patients with better SA regression (ΔSA > 35.9%), however, have a lower possibility of LR and might not need LLN clearance, in these cases, nCRT+TME is advised.

Risk factors for lateral lymph node metastasis based on the molecular profiling of rectal cancer

AIM

The association between molecular profiles and lateral lymph node metastasis (LLNM) in patients with rectal cancer remains unclear. Therefore, this study aimed to identify the molecular profiles of rectal cancer associated with LLNM.

METHOD

We retrospectively examined patients who underwent rectal cancer surgery with lateral lymph node dissection without preoperative treatment and whose surgically resected specimens were evaluated using multiomics-based analyses from 2014 to 2019. We compared the clinical characteristics and molecular profiles of patients with pathological LLNM (pLLNM+) with those of patients without (pLLNM-) and identified risk factors for LLNM.

RESULTS

We evaluated a total of 123 patients: 18 with and 105 without pLLNM. The accumulation of mutations in genes key for the development of colorectal cancer were similar between the groups, as was the tumour mutation burden. The distribution of consensus molecular subtypes (CMS) was significantly different between the groups (p = 0.0497). The pLLNM+ patients had a higher prevalance of CMS4 than the pLLNM- patients (77.8% vs. 51.4%). According to the multivariate analysis, the independent risk factors for LLNM were a short-axis diameter of the lateral lymph node of ≥6.0 mm and CMS4; furthermore, the presence of either or both had a sensitivity of 100% for the diagnosis of LLNM.

CONCLUSION

Lateral lymph node size and CMS4 are useful predictors of LLNM. The combination of CMS classification and size criteria was remarkably sensitive for the diagnosis of LLNM.

Prognostic Implications of Lateral Lymph Nodes in Rectal Cancer: A Population-Based Cross-sectional Study With Standardized Radiological Evaluation After Dedicated Training

BACKGROUND

There is an ongoing discussion regarding the prognostic implications of the presence, short-axis diameter, and location of lateral lymph nodes.

OBJECTIVE

To analyze lateral lymph node characteristics, the role of downsizing on restaging MRI, and associated local recurrence rates for patients with cT3-4 rectal cancer after MRI re-review and training.

DESIGN

Retrospective population-based cross-sectional study.

SETTINGS

This collaborative project was led by local investigators from surgery and radiology departments in 60 Dutch hospitals.

PATIENTS

A total of 3057 patients underwent rectal cancer surgery in 2016: 1109 had a cT3-4 tumor located ≤8 cm from the anorectal junction, of whom 891 received neoadjuvant therapy.

MAIN OUTCOME MEASURES

Local recurrence and (ipsi) lateral local recurrence rates.

RESULTS

Re-review identified 314 patients (35%) with visible lateral lymph nodes. Of these, 30 patients had either only long-stretched obturator (n = 13) or external iliac (n = 17) nodes, and both did not lead to any lateral local recurrences. The presence of internal iliac/obturator lateral lymph nodes (n = 284) resulted in 4-year local recurrence and lateral local recurrence rates of 16.4% and 8.8%, respectively. Enlarged (≥7 mm) lateral lymph nodes (n = 122) resulted in higher 4-year local recurrence (20.8%, 13.1%, 0%; p <.001) and lateral local recurrence (14.7%, 4.4%, 0%; p < 0.001) rates compared to smaller and no lateral lymph nodes, respectively. Visible lateral lymph nodes (HR 1.8 [1.1-2.8]) and enlarged lateral lymph nodes (HR 1.9 [1.1-3.5]) were independently associated with local recurrence in multivariable analysis. Enlarged lateral lymph nodes with malignant features had higher 4-year lateral local recurrence rates of 17.0%. Downsizing had no impact on lateral local recurrence rates. Enlarged lateral lymph nodes were found to be associated with higher univariate 4-year distant metastasis rates (36.4% vs 24.4%; p = 0.021), but this was not significant in multivariable analyses (HR 1.3 [0.9-1.]) and did not worsen overall survival.

LIMITATIONS

This study was limited by the retrospective design and total number of patients with lateral lymph nodes.

CONCLUSIONS

The risk of lateral local recurrence due to (enlarged) lateral lymph nodes was confirmed, but without the prognostic impact of downsizing after neoadjuvant therapy. These results point toward the incorporation of primary lateral lymph node size into treatment planning. See Video Abstract.

IMPLICACIONES PRONSTICAS DE LOS NDULOS LINFTICOS LATERALES EN EL CNCER DE RECTO UN ESTUDIO TRANSVERSAL DE BASE POBLACIONAL CON EVALUACIN RADIOLGICA ESTANDARIZADA DESPUS DE UN ENTRENAMIENTO ESPECFICO

ANTECEDENTES:Hay una discusión en curso acerca de las implicaciones pronósticas de la presencia, el diámetro del eje corto y la ubicación de los nódulos linfáticos laterales.OBJETIVO:Analizar las características de los nódulos linfáticos laterales, el rol de la reducción de tamaño en la IRM de reestratificación y las tasas de recurrencia local asociadas para pacientes con cáncer de recto cT3-4 después de una nueva revisión y entrenamiento de IRM.DISEÑO:Estudio transversal retrospectivo poblacional.CONFIGURACIÓN:Este proyecto colaborativo fue dirigido por investigadores locales de los departamentos de cirugía y radiología en 60 hospitales holandeses.PACIENTES:3057 pacientes fueron operados de cáncer de recto en 2016: 1109 tenían tumor cT3-4 ubicado a ≤8 cm de la unión anorrectal de los cuales 890 recibieron terapia neoadyuvante.INTERVENCIONES(S):Ninguna.PRINCIPALES MEDIDAS DE RESULTADO:recurrencia local y tasas de recurrencia local ipsilateral.RESULTADOS:Una nueva revisión identificó a 314 pacientes (35%) con nódulos linfáticos laterales visibles. 30 de estos pacientes tenían solo nódulos obturadores estirados (n = 13) o ilíacos externos (n = 17) y ambos no provocaron recurrencias locales laterales. La presencia de nódulos linfáticos laterales ilíacos internos/obturadores (n = 284) dio como resultado tasas de recurrencia local y recurrencia local lateral a los 4 años del 16.4% y el 8.8%, respectivamente. Los nódulos linfáticos laterales agrandados (≥7 mm) (n = 122) resultaron en una mayor recurrencia local a los 4 años (20.8%, 13.1%, 0%, p < 0.001) y recurrencia local lateral (14.7%, 4.4%, 0%, p < 0.001) en comparación con nódulos linfáticos más pequeños y sin nódulos linfáticos laterales, respectivamente. Los nódulos linfáticos laterales visibles (índice de riesgo 1,8 (1,1-2,8)) y los nódulos linfáticos laterales agrandados (índice de riesgo 1.9 (1.1-3.5)) se asociaron de forma independiente con la recurrencia local en el análisis multivariable. Los nódulos linfáticos laterales agrandados con características malignas tuvieron tasas de recurrencia local lateral a 4 años más altas del 17.0%. La reducción de tamaño no tuvo impacto en las tasas de recurrencia local lateral. Los nódulos linfáticos laterales agrandados se asociaron con tasas univariadas más altas de metástasis a distancia a los 4 años (36.4%, 24.4%, p = 0.021), pero no en el análisis multivariable (índice de riesgo 1.3 (0.9-1.8)), y no empeoró la supervivencia general.LIMITACIONES:Este estudio estuvo limitado por el diseño retrospectivo y el número total de pacientes con nódulos linfáticos laterales.CONCLUSIONES:Se confirmó el riesgo de recurrencia local lateral debido a los nódulos linfáticos laterales (agrandados), pero sin el impacto pronóstico de la reducción después de la terapia neoadyuvante. Estos resultados apuntan hacia la incorporación del tamaño del nódulo linfático lateral primario en la planificación del tratamiento. (Traducción-Dr. Aurian Garcia Gonzalez ).

Current perspectives on the management of lateral pelvic lymph nodes in rectal cancer

Significant controversies exist with regards to the optimal management of lateral pelvic lymph nodes metastases (mLLN) in patients with low rectal cancer. The differing views held by Japanese and Western clinicians on the management of mLLN have been well documented. However, the adequacy of pelvic lymph node dissection (PLND) or neoadjuvant chemoradiation (NACRT) alone in addition to total mesorectal excision (TME) have recently come into question, due to the relatively high incidence of lateral local recurrences following PLND and TME, or NACRT and TME alone. Recently, a more selective approach to PLND has been suggested, involving a combination of neoadjuvant therapy, followed by PLND only to patients in whom the oncological benefit is likely to outweigh the risk of potential adverse events. A number of studies have attempted to retrospectively identify certain nodal characteristics on preoperative imaging, such as nodal size, appearance, and size reduction following neoadjuvant therapy. However, no consensus has been reached regarding the optimal criteria for a selective approach to PLND, partly due to the heterogeneity and retrospective nature of most of these studies. This review aims to provide an overview of recent evidence with regards to the diagnostic challenges, considerations for, and outcomes of the current management strategies for mLLN in rectal cancer patients.

Coverage of Lateral Lymph Nodes in Rectal Cancer Patients with Routine Radiation Therapy Practice and Associated Locoregional Recurrence Rates

PURPOSE

Involved internal iliac and obturator lateral lymph nodes (LLNs) are a known risk factor for the occurrence of ipsilateral local recurrences (LLR) in rectal cancer. This study examined coverage of LLNs with routine radiation therapy practice in the Netherlands and associated LLR rates.

METHODS AND MATERIALS

Patients with a primary tumor ≤8 cm of the anorectal junction, cT3-4 stage, and at least 1 internal iliac or obturator LLN with short axis ≥5 mm who received neoadjuvant (chemo)radiation therapy, were selected from a national, cross-sectional study of patients with rectal cancer treated in the Netherlands in 2016. Magnetic resonance images and radiation therapy treatment plans were reviewed regarding segmented LLNs as gross tumor volume (GTV), location of LLNs within clinical target volume (CTV), and received proportion of the planned radiation therapy dose.

RESULTS

A total of 223 out of 3057 patients with at least 1 LLN ≥5 mm were selected. Of those, 180 (80.7%) LLNs were inside the CTV, of which 60 (33.3%) were segmented as GTV. Overall, 202 LLNs (90.6%) received ≥95% of the planned dose. Four-year LLR rates were not significantly higher for LLNs situated outside the CTV compared with those inside (4.0% vs 12.5%, P = .092) or when receiving <95% versus ≥95% of the planned radiation therapy dose (7.1% vs 11.3%, P = .843), respectively. Two of 7 patients who received a dose escalation of 60 Gy developed an LLR (4-year LLR rate of 28.6%).

CONCLUSIONS

This evaluation of routine radiation therapy practice showed that adequate coverage of LLNs was still associated with considerable 4-year LLR rates. Techniques resulting in better local control for patients with involved LLNs need to be explored further.

A Deep Learning Framework with Explainability for the Prediction of Lateral Locoregional Recurrences in Rectal Cancer Patients with Suspicious Lateral Lymph Nodes

Malignant lateral lymph nodes (LLNs) in low, locally advanced rectal cancer can cause (ipsi-lateral) local recurrences ((L)LR). Accurate identification is, therefore, essential. This study explored LLN features to create an artificial intelligence prediction model, estimating the risk of (L)LR. This retrospective multicentre cohort study examined 196 patients diagnosed with rectal cancer between 2008 and 2020 from three tertiary centres in the Netherlands. Primary and restaging T2W magnetic resonance imaging and clinical features were used. Visible LLNs were segmented and used for a multi-channel convolutional neural network. A deep learning model was developed and trained for the prediction of (L)LR according to malignant LLNs. Combined imaging and clinical features resulted in AUCs of 0.78 and 0.80 for LR and LLR, respectively. The sensitivity and specificity were 85.7% and 67.6%, respectively. Class activation map explainability methods were applied and consistently identified the same high-risk regions with structural similarity indices ranging from 0.772-0.930. This model resulted in good predictive value for (L)LR rates and can form the basis of future auto-segmentation programs to assist in the identification of high-risk patients and the development of risk stratification models.

Risk factors for lateral pelvic lymph node metastasis in patients with lower rectal cancer: a systematic review and meta-analysis

Background and objective

Lateral pelvic lymph node (LPLN) metastasis is one of the prominent reasons for local recurrence (LR) in patients with rectal cancer (RC). The evaluation criteria of lateral lymph node dissection (LLND) for patients in eastern (mainly in Japan) and western countries have been controversial. The aim of this study was to analyse the risk factors for LPLN metastasis in order to guide surgical methods.

Methods

We searched relevant databases (Embase (Ovid), Medline (Ovid), PubMed, Cochrane Library, and Web of Science) for articles published between 1 January 2000 and 05 October 2022 to evaluate the risk factors for LPLN metastasis in patients with RC in this meta-analysis.

Results

A total of 24 articles with 5843 patients were included in this study. The overall results showed that female sex, age <60 years, pretherapeutic CEA level >5 ng/ml, clinical T4 stage (cT4), clinical M1 stage (cM1), distance of the tumour from the anal verge (AV) <50 mm, tumour centre located below the peritoneal reflection (Rb), short axis (SA) of LPLN ≥8 mm before nCRT, short axis (SA) of LPLN ≥5 mm after nCRT, border irregularity of LPLN, tumour size ≥50 mm, pathological T3-4 stage (pT3-4), pathological N2 stage (pN2), mesorectal lymph node metastasis (MLNM), lymphatic invasion (LI), venous invasion (VI), CRM (+) and poor differentiation were significant risk factors for LPLN metastasis (P <0.05).

Conclusion

This study summarized almost all potential risk factors of LPLN metastasis and expected to provide effective treatment strategies for patients with LRC. According to the risk factors of lateral lymph node metastasis, we can adopt different comprehensive treatment strategies. High-risk patients can perform lateral lymph node dissection to effectively reduce local recurrence; In low-risk patients, we can avoid overtreatment, reduce complications and trauma caused by lateral lymph node dissection, and maximize patient survival and quality of life.

Evaluation of National Surgical Practice for Lateral Lymph Nodes in Rectal Cancer in an Untrained Setting

BACKGROUND

Involved lateral lymph nodes (LLNs) have been associated with increased local recurrence (LR) and ipsi-lateral LR (LLR) rates. However, consensus regarding the indication and type of surgical treatment for suspicious LLNs is lacking. This study evaluated the surgical treatment of LLNs in an untrained setting at a national level.

METHODS

Patients who underwent additional LLN surgery were selected from a national cross-sectional cohort study regarding patients undergoing rectal cancer surgery in 69 Dutch hospitals in 2016. LLN surgery consisted of either 'node-picking' (the removal of an individual LLN) or 'partial regional node dissection' (PRND; an incomplete resection of the LLN area). For all patients with primarily enlarged (≥7 mm) LLNs, those undergoing rectal surgery with an additional LLN procedure were compared to those  undergoing only rectal resection.

RESULTS

Out of 3057 patients, 64 underwent additional LLN surgery, with 4-year LR and LLR rates of 26% and 15%, respectively. Forty-eight patients (75%) had enlarged LLNs, with corresponding recurrence rates of 26% and 19%, respectively. Node-picking (n = 40) resulted in a 20% 4-year LLR, and a 14% LLR after PRND (n = 8; p = 0.677). Multivariable analysis of 158 patients with enlarged LLNs undergoing additional LLN surgery (n = 48) or rectal resection alone (n = 110) showed no significant association of LLN surgery with 4-year LR or LLR, but suggested higher recurrence risks after LLN surgery (LR: hazard ratio [HR] 1.5, 95% confidence interval [CI] 0.7-3.2, p = 0.264; LLR: HR 1.9, 95% CI 0.2-2.5, p = 0.874).

CONCLUSION

Evaluation of Dutch practice in 2016 revealed that approximately one-third of patients with primarily enlarged LLNs underwent surgical treatment, mostly consisting of node-picking. Recurrence rates were not significantly affected by LLN surgery, but did suggest worse outcomes. Outcomes of LLN surgery after adequate training requires further research.

Adding Induction Chemotherapy Before Chemoradiotherapy with Total Mesorectal Excision and Selective Lateral Lymph Node Dissection for Patients with Poor-Risk, Locally Advanced, Mid-to-Low Rectal Cancer May Improve Oncologic Outcomes: A Propensity Score-Matched Analysis

BACKGROUND

This study aimed to investigate whether the addition of induction chemotherapy before chemoradiotherapy (CRT) and total mesorectal excision (TME) with selective lateral lymph node dissection improves disease-free survival for patients with poor-risk, mid-to-low rectal cancer.

METHODS

The authors' institutional prospective database was queried for consecutive patients with clinical stage II or III, primary, poor-risk, mid-to-low rectal cancer who received neoadjuvant treatment followed by TME from 2004 to 2019. The outcomes for the patients who received induction chemotherapy before neoadjuvant CRT (induction-CRT group) were compared (via log-rank tests) with those for a propensity score-matched cohort of patients who received neoadjuvant CRT without induction chemotherapy (CRT group).

RESULTS

From 715 eligible patients, the study selected two matched cohorts with 130 patients each. The median follow-up duration was 5.4 years for the CRT group and 4.1 years for the induction-CRT group. The induction-CRT group had significantly higher rates of 3-year disease-free survival (83.5 % vs 71.4 %; p = 0.015), distant metastasis-free survival (84.3 % vs 75.2 %; p = 0.049), and local recurrence-free survival (98.4 % vs 94.4 %; p = 0.048) than the CRT group. The pathologically complete response rate also was higher in the induction-CRT group than in the CRT group (26.2 % vs 10.0 %; p < 0.001). Postoperative major complications (Clavien-Dindo classification ≥III) did not differ significantly between the two groups (12.3 % vs 10.8 %; p = 0.698).

CONCLUSIONS

The addition of induction chemotherapy to neoadjuvant CRT appeared to improve oncologic outcomes significantly, including disease-free survival, for the patients with poor-risk, mid-to-low rectal cancer who underwent TME using selective lateral lymph node dissection.

Management of lateral pelvic lymph nodes in rectal cancer

Lateral pelvic lymph node (LPLN) involvement occurs in 10%-25% of rectal cancer cases. Total mesorectal excision (TME) with routine LPLN dissection (LPLND) is predominantly applied in Japan whereas TME with neoadjuvant treatment are used in the West. LPLND is a morbid procedure and minimally invasive techniques may help reduce its morbidity. Selective lateral pelvic node dissection with TME following neoadjuvant treatment achieves acceptable disease-free and overall survival.

Global Status of Research on Lateral Lymph Nodes in Rectal Cancer from 1994 to 2022: A Bibliometric Analysis

Tremendous progress has been made in the field of lateral lymph nodes (LLNs) in rectal cancer, but no bibliometric analysis in this field has been carried out and published. To reveal the current status and trends in LLNs in rectal cancer, this bibliometric analysis was performed. Cooperation network, co-citation and keyword co-occurrence analyses were conducted. Annual publication, cooperation relationships among authors, institutions and countries, co-cited journal, co-cited author, co-cited reference and keywords were the main outcomes. A total of 345 studies were included in this bibliometric analysis. The number of articles published in this field has been increasing year by year. The authors, institutions and countries worked closely together in this field. Japan has the largest number of published articles, accounting for 51.59% of the total publications. International Journal of Colorectal Disease (30 papers, 8.70%) published the most papers in this field. The JCOG0212 trial was the most cited article. Preoperative chemoradiotherapy, multicenter, lateral lymph node dissection (LLND) and metastasis are recent hot keywords, and LLND had the highest burst strength. In conclusion, this bibliometric analysis found that Japanese institutions and authors dominated the field of LLNs in rectal cancer. The JCOG0212 trial was the most influential article, which had a significant impact on the development of guidelines. LLND is a hotspot in this field with the highest burst strength. Further prospective studies are needed in this field.

MRI radiomics signature to predict lymph node metastasis after neoadjuvant chemoradiation therapy in locally advanced rectal cancer

PURPOSE

To investigative the performance of MRI-radiomics analysis derived from T2WI and apparent diffusion coefficients (ADC) images before and after neoadjuvant chemoradiation therapy (nCRT) separately or simultaneously for predicting post-nCRT lymph node status in patients with locally advanced rectal cancer (LARC). MATERIALS AND METHODS: Eighty-three patients (training cohort, n = 57; validation cohort, n = 26) with LARC between June 2017 and December 2022 were retrospectively enrolled. All the radiomics features were extracted from volume of interest on T2WI and ADC images from baseline and post-nCRT MRI. Delta-radiomics features were defined as the difference between radiomics features before and after nCRT. Seven clinical-radiomics models were constructed by combining the most predictive radiomics signatures and clinical parameters selected from support vector machine. Receiver operating characteristic curve (ROC) was used to evaluate the performance of models. The optimum model-based LNM was applied to assess 5-years disease-free survival (DFS) using Kaplan-Meier analysis. The end point was clinical or radiological locoregional recurrence or distant metastasis during postoperative follow-up.

RESULTS

Clinical-deltaADC radiomics combined model presented good performance for predicting post-CRT LNM in the training (AUC = 0.895,95%CI:0.838-0.953) and validation cohort (AUC = 0.900,95%CI:0.771-1.000). Clinical-deltaADC radiomics-postT2WI radiomics combined model also showed good performances (AUC = 0.913,95%CI:0.838-0.953) in the training and (AUC = 0.912,95%CI:0.771-1.000) validation cohort. As for subgroup analysis, clinical-deltaADC radiomics combined model showed good performance predicting LNM in ypT0-T2 (AUC = 0.827;95%CI:0.649-1.000) and ypT3-T4 stage (AUC = 0.934;95%CI:0.864-1.000). In ypT0-T2 stage, clinical-deltaADC radiomics combined model-based LNM could assess 5-years DFS (P = 0.030).

CONCLUSION

Clinical-deltaADC radiomics combined model could predict post-nCRT LNM, and this combined model-based LNM was associated with 5-years DFS in ypT0-T2 stage.

Robotic and laparoscopic salvage lateral pelvic node dissection for the treatment of recurrent rectal cancer

BACKGROUND

The lateral pelvic sidewall is a major site of local recurrence after radical resection of rectal cancer. Salvage lateral pelvic node dissection (LPND) may be the only way to eliminate recurrent lateral pelvic nodes (LPNs). This study aimed to describe the technical details of robotic and laparoscopic salvage LPND and assess the short-term clinical and oncological outcomes in patients with recurrent LPNs who underwent salvage LPND by a minimally invasive approach for curative intent.

METHODS

Between September 2010 and 2019, 36 patients who underwent salvage surgery for LPN recurrence were retrospectively analyzed from a prospectively maintained database. Patients' characteristics, index operation, MRI findings, and perioperative and pathological outcomes were analyzed.

RESULTS

Eleven and 14 patients underwent robotic and laparoscopic salvage LPND, respectively. Eight patients (32.0%) underwent a combined salvage operation for resectable extra-pelvic sidewall metastases. There were four cases of open-conversion during the laparoscopic approach due to uncontrolled bleeding of iliac vessels. In these patients, metastatic LPNs were suspected of iliac vessel invasion and were found to be larger in size (median 15 mm; range 12-20) than that in patients who underwent successful LPND using the minimally invasive approach (median 10 mm; range 5-20). The median number of metastatic LPNs and harvested LPNs was 1 (range 0-3) and 6 (range 1-16), respectively. Six patients (24.0%) experienced postoperative complications including lymphoceles and voiding difficulties. During the follow-up (median 44.6 months; range 24.0-87.7), eight patients developed recurrences, mainly the lung and para-aortic lymph nodes, and one patient developed pelvic sidewall recurrence after laparoscopic salvage LPND. The 3-year disease-free survival and overall survival after salvage LPND were 66.4% and 79.2%, respectively.

CONCLUSIONS

Robotic and laparoscopic salvage LPND for recurrent LPNs are safe and feasible with favorable short-term surgical outcomes. However, the surgical approach should be carefully chosen in patients with large-sized and invasive recurrent LPNs.

Essential updates 2020/2021: Advancing precision medicine for comprehensive rectal cancer treatment

In the paradigm shift related to rectal cancer treatment, we have to understand a variety of new emerging topics to provide appropriate treatment for individual patients as precision medicine. However, information on surgery, genomic medicine, and pharmacotherapy is highly specialized and subdivided, creating a barrier to achieving thorough knowledge. In this review, we summarize the perspective for rectal cancer treatment and management from the current standard-of-care to the latest findings to help optimize treatment strategy.

Comparison of robotic versus laparoscopic lateral lymph node dissection for advanced lower rectal cancer: a retrospective study at two institutions

BACKGROUND

Lateral lymph node dissection (LLND) represents a technically challenging procedure. This study aimed to evaluate the perioperative, genitourinary functional and mid-term oncological outcomes of laparoscopic lateral lymph node dissection (LLLND) and robotic lateral lymph node dissection (RLLND) for advanced lower rectal cancer (ALRC).

METHODS

Between January 2015 and April 2021, consecutive patients who underwent RLLND and LLLND at two high-volume centres were enrolled. The perioperative outcomes, genitourinary function recovery and mid-term oncological outcomes of the patients were compared. A subgroup analysis of patients who underwent neoadjuvant chemoradiotherapy (nCRT) was performed.

RESULTS

A total of 205 patients were included in the analysis, with 95 in the RLLND group and 110 in the LLLND group. The patients in the RLLND group had a longer operative time, less blood loss, and more harvested internal iliac lymph nodes than did those in the LLLND group. In postoperative complication, urinary retention was less frequent in the RLLND group than in the LLLND group. Additionally, the RLLND group had better genitourinary function recovery. Similar results were also observed from the nCRT subgroup analysis. Moreover, there was no significant difference in mid-term oncological outcomes between the two groups. Further subgroup analysis indicated that the patients who underwent nCRT + LLLND/RLLND had better local control than those who underwent only LLLND/RLLND.

CONCLUSIONS

RLLND is safe and feasible for ALRC and is associated with more harvested internal iliac lymph nodes and better genitourinary function recovery. NCRT combined with minimally invasive LLND could constitute an improved strategy for ALRC.

Laparoscopic Extraperitoneal Approach for Lateral Pelvic Node Dissection in Rectal Cancer: Techniques and Short-Term Outcomes

BACKGROUND

Lateral pelvic lymph node dissection has been performed selectively in rectal cancer cases; however, it involves highly skilled techniques because of the complex adjacent anatomical structures.

MATERIALS AND METHODS

Laparoscopic EP-LPND was performed in Korea University Anam Hospital from June 2018, and short-term surgical outcomes were analyzed from June to December 2018. Among the patients with histologically diagnosed rectal adenocarcinoma, patients who were suspected Lateral pelvic lymph node metastasis at magnetic resonance imaging were selected for this procedure.

RESULTS

Seven patients underwent laparoscopic extraperitoneal approach for lateral pelvic lymph node dissection in the study period. The mean number of retrieved lymph node was 4.57, and metastatic lymph nodes were identified in 3 patients (42.8%). All of the lymph nodes with suspected metastasis preoperatively were removed in postoperative images. There was no immediate postoperative complication beyond the moderate grade associated with lateral pelvic lymph node dissection. The median follow-up was 9 months, and there were no local recurrence nor complications related to sexual and voiding functions.

CONCLUSIONS

The laparoscopic extraperitoneal approach might be an efficient way to perform lateral pelvic lymph node dissection using the same principles as the conventional method without violation of the peritoneum.

Metabolic and magnetic resonance imaging: complementary modalities for the preoperative assessment of lateral pelvic lymph nodes in rectal cancer

BACKGROUND

The management of lateral pelvic lymph nodes for rectal cancer is a topical and controversial issue. The aim of this study was to assess the relationship between lateral pelvic lymph node features on magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT) with oncological outcomes in patients with rectal cancer.

METHODS

A retrospective analysis of 284 patients with primary locally advanced rectal cancer treated with neoadjuvant therapy and surgical resection with curative intent between January 2003 and Dec 2018 was undertaken. From this study population, a select cohort of 77 patients with abnormal lateral pelvic lymph nodes on preoperative imaging had imaging re-analysed by radiologists blinded to clinical outcomes. Pre and post neoadjuvant therapy MRI and PET-CT lateral pelvic lymph node features were correlated with oncological outcomes.

RESULTS

A lateral pelvic lymph node short axis size ≥5 mm on post neoadjuvant therapy MRI was a significant predictor of worse 3-year local recurrence free survival (HR 8.35, P = 0.001). Lateral pelvic lymph node avidity on post neoadjuvant therapy PET-CT was a significant predictor of worse 3-year distant recurrence free survival (HR 5.62, P = 0.001). No correlation of oncological outcomes with overall survival was identified.

CONCLUSION

Lateral pelvic lymph node imaging features on post-neoadjuvant therapy MRI and PET-CT predicted those at risk of rectal cancer recurrence. Further studies are required to confirm these findings that suggest restaging MRI and PET-CT are complementary modalities for the preoperative assessment of lateral pelvic lymph nodes in rectal cancer.

Comparison of the clinical efficacy of a new prognostic stratification for duodenal adenocarcinoma with that of TNM staging: The importance of T status with regard to the prognosis

BACKGROUND

Although the current staging system and therapeutic strategy for duodenal adenocarcinoma (DA) focus on the N status, their validity has not been clarified. In this study, we evaluated the prognostic factors of DA and reviewed the current staging system.

METHODS

We included 105 patients who underwent surgical resection of DA in our department between September 2006 and October 2020. Patients with localised disease other than an early tumour (pT1a) were classified into the advanced group, and prognostic factors were compared with those for the Union for International Cancer Control (UICC) classification, 8th edition.

RESULTS

The 5-year overall survival (OS) rate in the advanced group (n = 55) was 73%. Multivariate analysis revealed that pT4 and pN2 statuses were independent prognostic factors for OS. The prognosis was stratified based on the pT4 and pN2 statuses, whereas the survival curves for patients with pStage II (pN0) and pStage IIIA (pN1) DA overlapped on staging according to the UICC classification. The new classification indicated a favourable prognosis for patients classified as pT1-3N1 stage IIIA (5-year OS, 86%), whereas the prognosis of patients with pT4N0-1 DA was similar to those classified as pT1-3N2 stage IIIB. Patients with pT4N2 DA had a similar prognosis (5-year OS, 24%) as those with metastases, and 75% of these patients showed distant metastasis within one year after surgery.

CONCLUSION

Both T and N statuses affect the prognosis of DA. Patients with pT4N2 DA may require intensive adjuvant chemotherapy. (238 words).

Optimal diagnostic criteria for lateral lymph node dissection using magnetic resonance imaging: a multicenter prospective study

BACKGROUND

LLND in cases with suspected lateral lymph node (LLN) metastasis has been focused on as a novel treatment strategy in recent years. However, the optimal indication for LLND in rectal cancer patients has not been determined. This study aimed to establish the optimal indication for lateral lymph node dissection (LLND) in patients with rectal cancer using magnetic resonance imaging (MRI).

METHODS

A total of 209 patients with rectal adenocarcinoma who underwent total mesorectal excision and LLND in 13 hospitals were prospectively registered. By matching the sizes of the harvested LNs and those in magnetic resonance imaging (MRI), the pathological outcome of each LN was confirmed one-by-one. Using parameters of the LLNs in MRI, the optimal diagnostic criteria for LLND were established.

RESULTS

Of 3241 harvested LLNs, including 83 metastatic nodes, 1010 (31.1%) were visualized on MRI. Although all parameters assessed showed strong correlations with the presence of metastasis, none of these parameters could discriminate metastatic LLNs from non-metastatic nodes with sufficient sensitivity. However, by using the combination of long axis and short/long ratio in pretreatment MRI, we could establish optimal criteria for LLND. The sensitivity and specificity of the criteria for LLN metastasis were 94.3% and 40.2%, respectively.

CONCLUSIONS

In conclusion, we established novel criteria for LLND in rectal cancer patients using MRI. Our criteria will be of great clinical use in determining indications for LLND.

Can patients with good tumor regression grading after neoadjuvant chemoradiotherapy be exempted from lateral lymph node dissection?

OBJECTIVE

To investigate whether lateral lymph node (LLN) dissection (LLND) can be exempted in patients with good tumor regression grading (TRG) after neoadjuvant chemoradiotherapy (nCRT)?

METHODS

A retrospective study was conducted on consecutive patients with advanced rectal cancer who underwent nCRT and total mesorectal resection plus selective LLND at our institution. The primary outcomes are the relationship between LLN metastasis (LLNM) and magnetic resonance imaging TRG (mrTRG) and the relationship between LLNM and pathological TRG (pTRG).

RESULTS

A total of 91 patients were included, of which 24 patients (26.4%) had LLNM, 67 patients (73.6%) had no LLNM. There were significant differences of the maximum short-axis of LLN before and after nCRT, short-axis reduction rate of the LLN with maximum short-axis, length diameter reduction rate of primary tumor, mrTRG, and pTRG between the two groups. Multivariate logistic regression showed that mrTRG (P = 0.026) and pTRG (P = 0.013) were independent predictors for LLNM. The combination used by mrTRG and the maximum short-axis of LLNs ≥ 8 mm before nCRT and the maximum short-axis of LLN ≥ 5 mm after nCRT achieved specificity of 0.970, positive predictive value (PPV) of 0.867, and negative predictive value (NPV) of 0.855. The same combination used by pTRG achieved the specificity of 0.970, PPV of 0.857 and NPV of 0.844.

CONCLUSION

The suspected positive LLNs tend to be sterilized by nCRT in patients who have a very good response to nCRT. It is rational to avoid LLND in patients whose primary tumor and LLNs both show good response to nCRT.

Case report: Indocyanine green fluorescence-guided imaging in laparoscope, a more sensitive detection technique of lateral lymph nodes metastases from rectal neuroendocrine tumors

Background

The diagnosis and surgical strategy of lateral lymph node metastases of rectal neuroendocrine tumors are still controversial. At present, the major diagnostic means rely on imaging examinations, but will be affected by the size of lymph nodes leading to false negativity. We provide a new technique to determine lateral lymph node metastases during surgery.

Clinical case

A 68-year-old man developed abdominal pain, bloating and fever for a month. Colonoscopy revealed the mass is 2.4 cm x 2.0 cm in size, with a wide stratum, poor mobility, and a rough but intact surface mucosa. Therefore, rectal neuroendocrine tumors (R-NET) were diagnosed. Multiple imaging methods, such as CT, octreotide imaging and endoscopic ultrasonography, have not found lateral lymph node metastases from rectal neuroendocrine tumors. But indocyanine green (ICG)-enhanced near-infrared fluorescence-guided imaging during surgery found left lateral lymph nodes metastases, which was proved by postoperative pathological examination.

Conclusions

We believe that applying ICG-enhanced near-infrared fluorescence-guided imaging in laparoscope can improve the detection of positive LLNs in those R-NET patients who did not reveal LNM on imaging examinations.

Clinical implication and management of rectal cancer with clinically suspicious lateral pelvic lymph node metastasis: A radiation oncologist's perspective

Rectal cancer is the eighth most common malignancy worldwide. With the introduction of total mesorectal excision (TME) and neoadjuvant chemoradiation (NCRT), intrapelvic local control has been remarkably improved. However, lateral pelvic recurrence remains problematic, especially in patients with clinically suspicious lateral pelvic lymph node (LPLN). LPLN dissection has been applied for the management of LPLN metastasis, mainly in Japan and other Eastern countries, while the role of NCRT is more emphasized and LPLN dissection is performed in very limited cases in Western countries. However, the optimal management strategy for patients with rectal cancer with suspicious LPLN metastasis has not been determined. Herein, we review the latest studies on the optimal management of LPLN metastasis to suggest the most appropriate treatment policies according to current evidence and discuss future research directions.

The Role of Preoperative Imaging in the Detection of Lateral Lymph Node Metastases in Rectal Cancer: A Systematic Review and Diagnostic Test Meta-analysis

BACKGROUND

Different techniques exist for the imaging of lateral lymph nodes in rectal cancer.

OBJECTIVE

This study aimed to compare the diagnostic accuracy of pelvic MRI, 18 F-FDG-PET/CT, and 18 F-FDG-PET/MRI for the identification of lateral lymph node metastases in rectal cancer.

DATA SOURCES

Data sources include PubMed, Embase, Cochrane Library, and Google Scholar.

STUDY SELECTION

All studies evaluating the diagnostic accuracy of pelvic MRI, 18 F-FDG-PET/CT, and 18 F-FDG-PET/MRI for the preoperative detection of lateral lymph node metastasis in patients with rectal cancer were selected.

INTERVENTIONS

The interventions were pelvic MRI, 18 F-FDG-PET/CT, and/or 18 F-FDG-PET/MRI.

MAIN OUTCOME MEASURES

Definitive histopathology was used as a criterion standard.

RESULTS

A total of 20 studies (1,827 patients) were included out of an initial search yielding 7,360 studies. The pooled sensitivity of pelvic MRI was 0.88 (95% CI, 0.85-0.91), of 18 F-FDG-PET/CT was 0.83 (95% CI, 0.80-0.86), and of 18 F-FDG-PET/MRI was 0.72 (95% CI, 0.51-0.87) for the detection of lateral lymph node metastasis. The pooled specificity of pelvic MRI was 0.85 (95% CI, 0.78-0.90), of 18 F-FDG-PET/CT was 0.95 (95% CI, 0.86-0.98), and of 18 F-FDG-PET/MRI was 0.90 (95% CI, 0.78-0.96). The area under the curve was 0.88 (95% CI, 0.85-0.91) for pelvic MRI and was 0.83 (95% CI, 0.80-0.86) for 18 F-FDG-PET/CT.

LIMITATIONS

Heterogeneity in terms of patients' populations, definitions of suspect lateral lymph nodes, and administration of neoadjuvant treatment.

CONCLUSIONS

For the preoperative identification of lateral lymph node metastasis in rectal cancer, this review found compelling evidence that pelvic MRI should constitute the imaging modality of choice. In contrast, to confirm the presence of lateral lymph node metastasis, 18 F-FDG-PET/MRI modalities allow discarding false positive cases because of increased specificity.

PROSPERO REGISTRATION NUMBER

CRD42020200319.

Retrospective evaluation of national MRI reporting quality for lateral lymph nodes in rectal cancer patients and concordance with prospective re-evaluation following additional training

Objectives

The presence and size of lateral lymph nodes (LLNs) are important factors influencing treatment decisions for rectal cancer. Awareness of the clinical relevance and describing LLNs in MRI reports is therefore essential. This study assessed whether LLNs were mentioned in primary MRI reports at a national level and investigated the concordance with standardised re-review.

Methods

This national, retrospective, cross-sectional cohort study included 1096 patients from 60 hospitals treated in 2016 for primary cT3-4 rectal cancer ≤ 8 cm from the anorectal junction. Abdominal radiologists re-reviewed all MR images following a 2-h training regarding LLNs.

Results

Re-review of MR images identified that 41.0% of enlarged (≥ 7 mm) LLNs were not mentioned in primary MRI reports. A contradictory anatomical location was stated for 73.2% of all LLNs and a different size (≥/< 7 mm) for 41.7%. In total, 49.4% of  all cases did not mention LLNs in primary MRI reports. Reporting LLNs was associated with stage (cT3N0 44.3%, T3N+/T4 52.8%, p = 0.013), cN stage (N0 44.1%, N1 48.6%, N2 59.5%, p < 0.001), hospital type (non-teaching 34.6%, teaching 52.2%, academic 53.2% p = 0.006) and annual rectal cancer resection volumes (low 34.8%, medium 47.7%, high 57.3% p < 0.001). For LLNs present according to original MRI reports (n = 226), 64.2% also mentioned a short-axis size, 52.7% an anatomical location and 25.2% whether it was deemed suspicious.

Conclusions

Almost half of the primary MRI reports for rectal cancer patients treated in the Netherlands in 2016 did not mention LLNs. A significant portion of enlarged LLNs identified during re-review were also not mentioned originally, with considerable discrepancies for location and size. These results imply insufficient awareness and indicate the need for templates, education and training.

Identification of patient subgroups with low risk of postoperative local recurrence for whom total mesorectal excision surgery alone is sufficient: a multicenter retrospective analysis

PURPOSE

For rectal cancer, a multimodality approach is mandatory including neoadjuvant chemoradiotherapy, neoadjuvant chemotherapy, and lateral pelvic lymph node (LPLN) dissection, in addition to the total mesorectal excision (TME). However, these treatments are associated with adverse events. It is important to select patients who do or do not need these treatments.

METHODS

We retrospectively analyzed patients with cStage II and III rectal cancer who underwent curative resection at three hospitals. Recurrence patterns were classified into three types; pelvic cavity, LPLN, and distant recurrences, and the risk factors for each pattern of recurrence were compared. We then analyzed the risk of recurrence in the patients who underwent TME alone.

RESULTS

In total, 506 patients were enrolled in this study. Pelvic cavity recurrence was significantly associated with clinical assumption of circumferential resection margin involvement (cCRM) (p < 0.001), distant recurrence was associated with cN positivity (p < 0.001), and LPLN recurrence was associated with pretreatment LPLN swelling ≥ 5 mm (p < 0.001), lower tumor location (p = 0.016), and serum CEA level > 5 ng/mL (p = 0.008). In patients without cCRM and swollen LPLN, the local recurrence rate was extremely low even if they underwent TME alone; the 5-year recurrence rates of pelvic cavity and LPLN were 2.2% and 1.9%, respectively.

CONCLUSION

Additional treatments to TME for rectal cancer need to be performed based on the risk factors for each recurrence pattern.

Effect of lateral lymph nodes without malignant characteristics on the prognosis of patients with rectal cancer

Background: Lateral lymph node (LLN) metastasis is a poor prognostic factor for rectal cancer patients. However, the effect of LLNs without malignant characteristics on the prognosis of rectal cancer patients has been uncertain. Methods: Consecutive patients who underwent laparoscopic-assisted low anterior resection were included. Patients with MRI-detected LLNs, but without malignant characteristics, were compared with patients with no MRI-detected LLNs. Results: The local recurrence rate was higher in the LLN-present group than in the LLN-absent group (9.8% vs 2.5%; p = 0.056). The overall survival of patients with no MRI-detected LLNs was significantly better than that of patients with MRI-detected LLNs (p = 0.021). Conclusion: The presence of LLNs, even without malignant features, may lead to worse local control and overall survival.

Computed tomography texture analysis for the prediction of lateral pelvic lymph node metastasis of rectal cancer

BACKGROUND

This study aimed to investigate the usefulness of computed tomography (CT) texture analysis in the diagnosis of lateral pelvic lymph node (LPLN) metastasis of rectal cancer.

METHODS

This was a retrospective cohort study of 45 patients with rectal cancer who underwent surgery with LPLN dissection at Tokushima University Hospital from January 2017 to December 2021. The texture analysis of the LPLNs was performed on preoperative CT images, and 18 parameters were calculated. The correlation between each parameter and pathological LPLN metastasis was evaluated. The texture parameters were compared between pathologically metastasis-positive LPLNs and metastasis-negative LPLNs.

RESULTS

A total of 40 LPLNs were extracted from 25 patients by preoperative CT scans. No LPLNs could be identified in the remaining 19 patients. Eight of the 25 patients had pathologically positive LPLN metastasis. Extracted LPLNs were analyzed by the texture analysis. Pathologically metastasis-positive LPLNs had significantly lower mean Hounsfield unit, gray-level co-occurrence matrix (GLCM) energy, and GLCM Entropy_log2 values, and a significantly larger volume than pathologically metastasis-negative LPLNs. Multivariate analysis revealed that the independent predictive factors for LPLN metastasis were volume (a conventional parameter) (odds ratio 7.81, 95% confidence interval 1.42-43.1, p value 0.018) and GLCM Entropy_log2 (a texture parameter) (odds ratio 12.7, 95% confidence interval 1.28-126.0, p value 0.030). The combination of both parameters improved the diagnostic specificity while maintaining the sensitivity compared with each parameter alone.

CONCLUSION

Combining the CT texture analysis with conventional diagnostic imaging may increase the accuracy of the diagnosis of LPLN metastasis of rectal cancer.

Predictors and histological effects of preoperative chemoradiotherapy for rectal cancer and control of lateral lymph node metastasis

Introduction

Standard treatment strategy for low rectal cancer in Japan is different from Western countries. Total mesorectum excision (TME) + lateral lymph node dissection (LLND) is mainly carried out in Japan, whereas neoadjuvant chemoradiotherapy (nCRT) + TME is selected in Western countries. There is no clear definition of preoperative diagnosis of lateral lymph node metastasis. If we can predict lateral lymph node swelling that can be managed by nCRT from lateral lymph node swelling that require surgical resection, clinical benefit is significant. In the current study we assessed characteristics of the lateral lymph node recurrence (LLNR) and LLND that can be managed by nCRT.

Patients and Methods

Patients with low rectal cancer (n = 168) underwent nCRT between 2009 and 2016. We evaluated CEA, neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and lateral lymph node short axis pre and post nCRT, respectively, and also evaluated tumor shrinkage rate, tumor regression grade (TRG). We evaluated the relationship between each and LLNR.

Results

LLND was not carried out all patients. Factors associated with LLNR were PLR and lymph node short axis pre and post nCRT. (p = 0.0269, 0.0278, p < 0.0001, p < 0.0001, respectively). Positive recurrence cut-off values of lateral lymph node short-axis calculated were 11.6 mm pre nCRT and 5.5 mm post nCRT.

Conclusion

Results suggest that PLR before and after CRT was associated with control of LLNR, and LLND should be performed on lateral lymph nodes with short-axis of 5 mm and 11 mm pre and post nCRT.

Development and External Validation of a Preoperative Nomogram for Predicting Lateral Pelvic Lymph Node Metastasis in Patients With Advanced Lower Rectal Cancer

Background

The preoperative prediction of lateral pelvic lymph node (LPLN) metastasis is crucial in determining further treatment strategies for advanced lower rectal cancer patients. In this study, we established a nomogram model to preoperatively predict LPLN metastasis and then externally validated the accuracy of this model.

Methods

A total of 287 rectal cancer patients who underwent LPLN dissection were included in this study. Among them, 200 patients from the Peking University First Hospital were included in the development set, and 87 patients from the First Affiliated Hospital of Xi’an Jiaotong University were included in the independent external validation set. Multivariate logistic regression analysis was used to develop the nomogram. The performance of the nomogram was assessed based on its calibration, discrimination, and clinical utility.

Results

Five factors (differentiation grade, extramural vascular invasion, distance of the tumor from the anal verge, perirectal lymph node status, and largest short-axis diameter of LPLN) were identified and included in the nomogram. The nomogram developed based on the analysis showed robust discrimination with an area under the receiver operating characteristic curve (AUC) of 0.878 (95% CI, 0.824–0.932). The validation set showed good discrimination with an AUC of 0.863 (95% CI, 0.779–0.948). Decision curve analysis showed that the nomogram was clinically useful.

Conclusions

The present study proposed a clinical-imaging nomogram with a combination of clinicopathological risk factors and imaging features. After external verification, the predictive power of the nomogram model was satisfactory, and it is expected to be a convenient, visual, and personalized clinical tool for assessing the risk of LPLN metastasis in advanced lower rectal cancer patients.

Establishment and validation of a nomogram for predicting potential lateral pelvic lymph node metastasis in low rectal cancer

BACKGROUND

Identifying lateral pelvic lymph node (LPN) metastasis in low rectal cancer is crucial before treatment. Several risk factors and prediction models for LPN metastasis have been reported. However, there is no useful tool to accurately predict LPN metastasis. Therefore, we aimed to construct a nomogram for predicting LPN metastasis in rectal cancer.

METHODS

We analyzed the risk factors for potential LPN metastasis by logistic regression analysis in 705 patients who underwent primary resection of low rectal cancer. We included patients at 49 institutes of the Japan Society of Laparoscopic Colorectal Surgery between June 2010 and February 2012. Clinicopathological factors and magnetic resonance imaging findings were evaluated. The nomogram performance was assessed using the c-index and calibration plots, and the nomogram was validated using an external cohort.

RESULTS

In the univariable logistic regression analysis, age, sex, carcinoembryonic antigen, tumor location, clinical T stage, tumor size, circumferential resection margin (CRM), extramural vascular invasion (EMVI), and the short and long axes of LPN and perirectal lymph node (PRLN) were nominated as risk factors for potential LPN metastasis. We identified a combination of the short axis of LPN, tumor location, EMVI, and short axis of PRLN as optimal for predicting potential LPN metastasis and developed a nomogram using these factors. This model had a c-index of 0.74 and was moderately calibrated and well-validated.

CONCLUSIONS

This is the first study to construct a well-validated nomogram for predicting potential LPN metastasis in rectal cancer, and its performance was high.

The Role of Simultaneous Integrated Boost in Locally Advanced Rectal Cancer Patients with Positive Lateral Pelvic Lymph Nodes

Aims: Between 11 to 14% of patients with locally advanced rectal cancer (LARC) have positive lateral pelvic lymph nodes (LPLN) at diagnosis, related to a worse prognosis with a 5-year survival rate between 30 to 40%. The best treatment choice for this group of patients is still a challenge. The optimal radiotherapy (RT) dose for LPLN patients has been investigated. Methods: We retrospectively collected data from LARC patients with LPLN at the primary staging MRI, treated in our center from March 2003 to December 2020. Patients underwent a neoadjuvant concomitant chemo-radiotherapy (CRT) treatment on the primary tumor (T), mesorectum, and pelvic nodes, associated with a fluoride-based chemotherapy. The total reached dose was 45 Gy at 1.8 Gy/fr on the elective sites and 55 Gy at 2.2 Gy/fr on the disease and mesorectum. Patients were divided in two groups based on whether they received a simultaneous integrated RT boost on the LPLN or not. Overall Survival (OS), Disease Free Survival (DFS), Metastasis Free Survival (MFS), and Local Control (LC) were evaluated in the whole group and then compared between the two groups. Results: A total of 176 patients were evaluated: 82 were included in the RT boost group and 94 in the non-RT boost group. The median follow-up period was 57.8 months. All the clinical endpoint (OS, DFS, MFS, LC), resulted were affected by the simultaneous integrated boost on LPLN with a survival rate of 84.7%, 79.5%, 84.1%, and 92%, respectively, in the entire population. From the comparison of the two groups, there was a statistical significance towards the RT boost group with a p < 0.006, 0.030, 0.042, 0.026, respectively. Conclusions: Concomitant radiotherapy boost on positive LPLN has shown to be beneficial on the survival outcomes (OS, DFS, MFR, and LC) in patients with LARC and LPLN. This analysis demonstrates that a higher dose of radiotherapy on positive pelvic lymph nodes led not only to a higher local control but also to a better survival rate. These results, if validated by future prospective studies, can bring a valid alternative to the surgery dissection without the important side effects and permanent disabilities observed during the years.

Comparison of postoperative laparoscopic and open total mesorectal excision on lower urinary tract function in men with rectal cancer

OBJECTIVES

This study investigated male voiding dysfunction (VD) or lower urinary tract function in rectal cancer (RC) patients after laparoscopic or open total mesorectal excision with pelvic autonomic nerve preservation (PANP).

METHODS

One hundred and eighty-seven male RC patients admitted between January 2016 and May 2019 were enrolled in this study, 112 of whom underwent laparoscopic total mesorectal excision (LTME) and 75 underwent open total mesorectal excision (OTME). The International Prostatic Symptom Score (IPSS) was compared between the two groups.

RESULTS

The postoperative IPSS in patients with RC was elevated on day 7 and gradually decreased during the first month after surgery. Compared with the OTME group, the IPSS scores decreased less in the LTME group at week 1, and months 1 and 3 postoperatively (6.82 ± 2.13 vs 10.15 ± 3.86, 5.70 ± 2.45 vs 7.21 ± 2.0, and 5.01 ± 2.09 vs 5.75 ± 2.55, respectively; P < 0.05). The VD rate was significantly lower in the LTME group than the OTME group at 1, 2, and 3 weeks postoperatively (21.4% vs 26.8%,13.4% vs 25.3%, and 9.8% vs18.6%, respectively; P < 0.05); however, there was no major difference in the incidence of VD 6 months postoperatively between the two groups (P > 0.05). VD was more frequent in the OTME group than the LTME group 6 months postoperatively, but the difference was not statistically significant (odds ratio = 1.857, 95% CI, 0.964-3.645, P = 0.064).

CONCLUSIONS

LTME may be superior to OTME with respect to PANP of lower urinary tract function in males with RC.

Impact of the viability assessment of lateral lymph node metastasis in rectal cancer after neoadjuvant chemoradiotherapy

PURPOSE

Preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME) without lateral lymph node (LLN) dissection is widely performed for lower advanced rectal cancer. However, it is unclear whether residual cancer cells in the LLNs undergo apoptosis, disappear, or regrow if unresected.

METHODS

Overall, 293 consecutive patients with T3/4 rectal cancer who underwent CRT followed by radical surgery between September 2003 and December 2018 were retrospectively reviewed. We assessed apoptosis of the residual primary tumor, mesorectum lymph nodes (MLN), and LLN using M30 cytoDEATH immunostaining and evaluated the degree of apoptosis. The difference in the prognosis of the lateral lymph node metastasis positive (LLNM +) and lateral lymph node metastasis negative (LLNM-) groups was assessed.

RESULTS

There were 31 patients (10.6%) who were diagnosed with a complete response by hematoxylin and eosin (HE) staining. The residual cancer cells showed complete apoptosis in the primary lesion in 28 patients, in the metastatic MLN in only two patients, and in the metastatic LLN in one patient. The LLNM + group had a significantly poorer distant recurrence, recurrence-free survival, and overall survival than the LLNM- group.

CONCLUSION

The majority of the residual cancer tissue in LNs observed by HE staining was found to be non-apoptotic. If LLN metastasis is suspected on pretreatment imaging, performing LLN dissection together with TME should be considered.

Combination of extramural venous invasion and lateral lymph node size detected with magnetic resonance imaging is a reliable biomarker for lateral lymph node metastasis in patients with rectal cancer

PURPOSE

Pathological extramural venous invasion (EMVI) is defined as the active invasion of malignant cells into veins beyond the muscularis propria in colorectal cancer. It is associated with poor prognosis and increases the risk of disease recurrence. Specific findings on MRI (termed MRI-EMVI) are reportedly associated with pathological EMVI. In this study, we aimed to identify risk factors for lateral lymph node (LLN) metastasis related to rectal cancer and to evaluate whether MRI-EMVI could be a new and useful imaging biomarker to help LLN metastasis diagnosis besides LLN size.

METHODS

We investigated 67 patients who underwent rectal resection and LLN dissection for rectal cancer. We evaluated MRI-EMVI grading score and examined the relationship between MRI-EMVI and LLN metastasis.

RESULTS

Pathological LLN metastasis was detected in 18 cases (26.9%), and MRI-EMVI was observed in 32 cases (47.8%). Patients were divided into two cohorts, according to LLN metastasis. Multivariate analyses demonstrated that higher risk of LLN metastasis was significantly associated with MRI-EMVI (P = 0.0112) and a short lateral lymph node axis (≥ 5 mm) (P = 0.0002). The positive likelihood ratios of MRI-EMVI alone, LLN size alone, and the combination of both factors were 2.12, 4.84, and 16.33, respectively. Patients negative for both showed better 2-year relapse-free survival compared to other patients (84.4% vs. 62.1%, P = 0.0374).

CONCLUSIONS

MRI-EMVI was a useful imaging biomarker for identifying LLN metastasis in patients with rectal cancer. The combination of MRI-EMVI and LLN size can improve diagnostic accuracy.

A case report of the transanal lateral lymph node dissection with a combined abdominal assisted approach for the lower rectal cancer

Introduction

Low and mid rectal cancer cells have the tendency to spread in the lateral pelvic lymph node (LPLN). The Japanese guidelines recommend systematic lymph node dissection when a positive LPLN is suspected or in stages II–III rectal cancer. However, laparoscopic lymph node dissection is complex and challenging. We introduce transanal LPLN dissection using an abdominal approach.

Presentation of case

A 78-year-old man was diagnosed with advanced rectal cancer. Computed tomography and magnetic resonance imaging showed lower rectal wall thickening and bilateral lateral lymph node swelling. We performed laparoscopic abdominal peritoneal resection with combined bilateral LPLN dissection using abdominal and transanal approaches. He had an uneventful postoperative course with no signs of recurrence at the 5-month follow-up.

Discussion

LPLN metastases for low rectal cancer especially occur at the bottom of the deep pelvic spaces. As laparoscopic LPLND for low rectal cancer can be complicated, we adopted abdominal and transanal approaches, which provide the advantage of an anatomical view. This procedure may improve lateral pelvic anatomical structure viewing, and may offer advantages over laparoscopic abdominal approaches for visualizing and dissecting LPLNs.

Conclusion

Curative resection has become available for rectal cancer with transanal LPLN dissection. LPLN dissection with combined abdominal and transanal approaches is a feasible treatment for advanced rectal cancer.

•

Laparoscopic lymph node dissection for low rectal cancer is complex and challenging.

•

The surgical view around the distal internal lymph node (#263d) and the Alcock duct improved with the transanal approach.

•

Ta-LPLND combined with abdominal dissection is feasible and effective for rectal cancer.

The Effectiveness of Machine Learning in Predicting Lateral Lymph Node Metastasis From Lower Rectal Cancer: A Single Center Development and Validation Study

AIM

Accurate preoperative diagnosis of lateral lymph node metastasis (LLNM) from lower rectal cancer is important to identify patients who require lateral lymph node dissection (LLND). We aimed to create an effective prediction model for LLNM using machine learning by combining preoperative information.

METHODS

We retrospectively examined patients who underwent primary rectal cancer surgery with unilateral or bilateral LLND between April 2010 and March 2020 at a single institution. Using the machine learning software "Prediction One" (Sony Network Communications), we developed a prediction model in the training cohort that included 267 consecutive patients (500 sides) from April 2010. Clinicopathological data obtained from the preoperative examinations were used as the learning items. In the validation cohort that included subsequent patients until March 2020, we compared the discriminating powers of the prediction model and the conventional method using the short-axis diameter of the largest lateral lymph node, as detected on magnetic resonance imaging.

RESULTS

The area under the receiver operating characteristic curve (AUC) of the prediction model was 0.903 in the validation cohort comprising 56 patients (107 sides). This indicated significantly higher predictive power than that of the conventional method (AUC = 0.754; P = .022). Using the cutoff values defined in the training cohort, the accuracy, sensitivity, and specificity of the prediction model were 80.4%, 90.0%, and 79.4%, respectively. The model was able to correctly predict four of five sides comprising LLNM with the short-axis diameters ≤4 mm.

CONCLUSION

Machine learning contributed to the creation of an effective prediction model for LLNM.

Lateral Pelvic Lymph Node Dissection After Neoadjuvant Chemoradiotherapy in Patients With Rectal Cancer: A Single-Center Experience and Literature Review

Purpose

We aimed to evaluate the surgicopathological outcomes of lateral pelvic lymph node dissection (LPLD) and long-term oncological outcomes of selective LPLD after neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer and compare them to those of total mesorectal excision (TME) alone based on pretreatment magnetic resonance imaging (MRI).

Methods

We compared the TME-alone group (2001–2009, n=102) with the TME with LPLD group (2011–2016, n=69), both groups having lateral lymph nodes (LLNs) of ≥5 mm in short axis diameter. The surgicopathological outcomes were analyzed retrospectively. Oncological outcomes were analyzed using the Kaplan-Meier method.

Results

The rates of overall postoperative 30-day morbidity (42.0% vs. 26.5%, P=0.095) and urinary retention (13.7% vs. 10.1%, P=0.484) were not significantly different between the LPLD and TME-alone groups, respectively. Pathologically proven LLN metastasis was identified in 24 (34.8%) LPLD cases after nCRT. The LPLD group showed a lower 5-year local recurrence (LR) rate (27.9% vs. 4.6%, P<0.001) and better recurrence-free survival (RFS) (59.6% vs. 78.2%, P=0.008) than those of the TME-alone group, while the 5-year overall survival was not significantly different between the 2 groups (76.2% vs. 86.5%, P=0.094).

Conclusion

This study suggests that LPLD is a safe and feasible procedure. The oncological outcomes suggest that selective LPLD improves LR and RFS in patients with clinically suspicious LLNs on pretreatment MRI. Considering that lateral nodal disease is not common, a multicenter large-scale study is necessary.

Risk factors and prognostic significance of lateral pelvic lymph node dissection after neoadjuvant chemoradiotherapy for rectal patients with clinically suspected lateral lymph node metastasis

AIM

It is still controversial whether the addition of lateral pelvic lymph node (LPN) dissection (LPND) to total mesorectal excision (TME) can provide a survival benefit after neoadjuvant chemoradiotherapy (nCRT) in rectal cancer patients with pathological lateral lymph node metastasis (LPNM).

METHODS

Patients with clinically suspected LPNM who underwent nCRT followed by TME + LPND were systematically reviewed and divided into the positive LPN group (n = 15) and the negative LPN group (n = 58). Baseline characteristics, clinicopathological data and survival outcomes were collected and analysed.

RESULTS

Of the 73 patients undergoing TME + LPND after nCRT, the pathological LPNM rate was 20.5% (15/73). Multivariate analysis showed that a post-nCRT LPN short diameter ≥ 7 mm (OR 49.65; 95% CI 3.98-619.1; P = 0.002) and lymphatic invasion (OR 9.23; 95% CI 1.28-66.35; P = 0.027) were independent risk factors for pathological LPNM. The overall recurrence rate of patients with LPNM was significantly higher than that of patients without LPNM (60.0% vs 27.6%, P = 0.018). Multivariate regression analysis identified that LPNM was an independent risk factor not only for overall survival (OS) (HR 3.82; 95% CI 1.19-12.25; P = 0.024) but also for disease-free survival (DFS) (HR 2.33; 95% CI 1.02-5.14; P = 0.044). Moreover, N1-N2 stage was another independent risk factor for OS (HR 7.41; 95% CI 1.63-33.75; P = 0.010).

CONCLUSIONS

Post-nCRT LPN short diameter ≥ 7 mm and lymphatic invasion were risk factors for pathological LPNM after nCRT. Furthermore, patients with pathological LPNM still show an elevated overall recurrence rate and poor prognosis after TME + LPND. Strict patient selection and intensive perioperative chemotherapy are crucial factors to ensure the efficacy of LPND.