Survival benefit of lateral lymph node dissection according to the region of involvement and the number of lateral lymph nodes involved

Feasibility, Indications, and Prognostic Significance of Selective Lateral Pelvic Lymph Node Dissection After Preoperative Chemoradiotherapy in Middle/Low Rectal Cancer: Results of a Multicenter Lateral Node Study in China

BACKGROUND

Lateral pelvic lymph node dissection after preoperative chemoradiotherapy can decrease local recurrence to lateral compartments, thereby providing survival benefits.

OBJECTIVE

The safety of lateral pelvic lymph node dissection after preoperative chemoradiotherapy was investigated, and the surgical indications and survival benefits of lateral pelvic lymph node dissection were established on the basis of preoperative characteristics.

DESIGN

A multicenter retrospective study.

SETTINGS

Three hospitals in China.

PATIENTS

Four hundred nine patients with clinical evidence of lateral pelvic lymph node metastasis.

INTERVENTIONS

Patients who received lateral pelvic lymph node dissection were divided into 2 groups depending on whether they received chemoradiotherapy (n = 139) or not (n = 270).

MAIN OUTCOME MEASURES

The safety, indications, and survival benefits of lateral pelvic lymph node dissection after preoperative chemoradiotherapy were investigated.

RESULTS

The surgery times were significantly prolonged by preoperative chemoradiotherapy (291.3 vs 265.5 min; p = 0.021). Multivariate analysis demonstrated that poor/mucinous/signet-ring adenocarcinoma (OR = 4.42, 95% CI, 2.24-11.27; p = 0.031) and postchemoradiotherapy lateral pelvic lymph node short-axis diameter ≥7 mm (OR = 15.2, 95% CI, 5.89-53.01; p < 0.001) were independent predictive factors for lateral pelvic lymph node metastasis. Multivariate prognostic analysis showed that swollen lateral pelvic lymph nodes beyond the obturator or internal iliac as well as the involvement of 3 or more lateral pelvic lymph nodes were independent adverse prognostic factors.

LIMITATIONS

The retrospective nature of the study and the small sample size were the limitations of this study.

CONCLUSIONS

Preoperative chemoradiotherapy combined with lateral pelvic lymph node dissection is a practicable procedure with acceptable morbidity. Postchemoradiotherapy lateral pelvic lymph node short-axis diameter ≥7 mm and poor/signet/mucinous adenocarcinoma could be used for predicting lateral pelvic lymph node metastasis after chemoradiotherapy. However, lateral pelvic lymph node dissection should be carefully considered in patients with swollen lateral pelvic lymph nodes beyond the obturator or internal iliac region or involvement of multiple lateral pelvic lymph nodes. See Video Abstract at http://links.lww.com/DCR/C133 .

VIABILIDAD, INDICACIONES E IMPORTANCIA PRONSTICA DE LA DISECCIN SELECTIVA DE GANGLIOS LINFTICOS PLVICOS LATERALES DESPUS DE QUIMIORRADIOTERAPIA PREOPERATORIA EN CNCER DE RECTO MEDIO/INFERIOR RESULTADOS DE UN ESTUDIO MULTICNTRICO DE GANGLIOS LATERALES EN CHINA

ANTECEDENTES:La disección de los ganglios linfáticos pélvicos laterales después de la quimiorradioterapia preoperatoria puede disminuir la recurrencia local en los compartimentos laterales, lo que brinda beneficios de supervivencia.OBJETIVO:Se investigó la seguridad de la disección de los ganglios linfáticos pélvicos laterales después de la quimiorradioterapia preoperatoria, y se establecieron las indicaciones quirúrgicas y los beneficios de supervivencia de la disección de los ganglios linfáticos pélvicos laterales en función de las características preoperatorias.DISEÑO:Estudio retrospectivo multicéntrico.ESCENARIO:Tres hospitales en China.PACIENTES:Cuatrocientos nueve pacientes con evidencia clínica de metástasis en los ganglios linfáticos pélvicos laterales.INTERVENCIONES:Los pacientes que recibieron disección de ganglios linfáticos pélvicos laterales se dividieron en dos grupos dependiendo de si recibieron quimiorradioterapia (n = 139) o no (n = 270).PRINCIPALES MEDIDAS DE RESULTADO:Se investigaron la seguridad, las indicaciones y los beneficios de supervivencia de la disección de los ganglios linfáticos pélvicos laterales después de la quimiorradioterapia preoperatoria.RESULTADOS:Los tiempos de cirugía se prolongaron significativamente con la quimiorradioterapia preoperatoria (291,3 vs 265,5 min, p = 0,021). El análisis multivariable demostró que el adenocarcinoma mal diferenciado/mucinoso/en anillo de sello (odds ratio = 4,42, intervalo de confianza del 95%, 2,24-11,27; p = 0,031) y el diámetro del eje corto de los ganglios linfáticos pélvicos laterales después de la quimiorradioterapia ≥7 mm (odds ratio = 15,2, intervalo de confianza del 95%, 5,89-53,01; p < 0,001) fueron factores predictivos independientes de metástasis en los ganglios linfáticos pélvicos laterales. El análisis pronóstico multivariable mostró que la inflamación de los ganglios linfáticos pélvicos laterales más allá del obturador o la ilíaca interna, así como la afectación de tres o más ganglios linfáticos pélvicos laterales, eran factores pronósticos adversos independientes.LIMITACIONES:La naturaleza retrospectiva del estudio y el pequeño tamaño de la muestra.CONCLUSIONES:La quimiorradioterapia preoperatoria combinada con la disección de los ganglios linfáticos pélvicos laterales es un procedimiento practicable con una morbilidad aceptable. Posterior a la quimiorradioterapia, el diámetro del eje corto de los ganglios linfáticos pélvicos laterales ≥7 mm y el adenocarcinoma pobre/en sello/mucinoso podrían usarse para predecir la metástasis en los ganglios linfáticos pélvicos laterales después de la quimiorradioterapia. Sin embargo, la disección de los ganglios linfáticos pélvicos laterales debe considerarse cuidadosamente en pacientes con ganglios linfáticos pélvicos laterales inflamados más allá del obturador o de la región ilíaca interna o compromiso de múltiples ganglios linfáticos pélvicos laterales. Consulte Video Resumen en http://links.lww.com/DCR/C133 . (Traducción-Dr. Felipe Bellolio ).

Optimization of therapeutic strategies for selective lateral lymph node dissection after neoadjuvant chemoradiotherapy in patients with rectal cancer with clinical suspected lateral lymph node metastasis

Background

Selective lateral lymph node (LLN) dissection with total mesorectal excision after neoadjuvant chemoradiotherapy (nCRT) is pointed out to reduce lateral compartment recurrence and to improve survival in patients with rectal cancer with LLN metastases. This study aimed to explore the safety, surgical indications, and survival outcomes of LLN dissection after nCRT.

Methods

This multicenter retrospective study included patients with rectal cancer with clinical evidence of LLN metastases (n = 466) treated across three hospitals in China. Patients who underwent total mesorectal excision and LLN dissection were grouped into nCRT (n = 155) and non-nCRT (n = 291), respectively. Propensity score matching was used to minimize selection bias.

Results

After matching, nCRT did not significantly increase the surgery duration, intraoperative blood loss or postoperative complications (P > 0.05). In a multivariate logistic regression analysis, poor/mucinous/signet adenocarcinoma (P = 0.042) and post-nCRT LLN short diameter ≥7 mm (P < 0.001) were independent risk factors for pathological LLN metastasis after nCRT. Overall survival (P < 0.001) and disease-free survival (P < 0.001) were significantly worse in patients with LLN metastasis, which was, however, not an independent risk factor for survival after eliminating confounders. Multivariate prognostic analysis of 40-patient subset with pathological LLN metastasis showed that distant metastasis, metastasis beyond the obturator or internal iliac region, and ≥2 LLN metastasis were independent predictors of poor overall survival.

Conclusions

Selective LLN dissection after nCRT is safe and feasible with acceptable perioperative outcomes. Patients with a post-nCRT LLN short diameter ≥7 mm or poor/mucinous/signet adenocarcinoma should receive supplementary LLN dissection after nCRT. However, patients with distant metastasis, metastasis beyond the obturator or internal iliac region, and involvement of ≥2 LLN may not benefit from LLN dissection, and LLN dissection should be carefully considered in such patients.

Role of one-step nucleic acid amplification in colorectal cancer lymph node metastases detection

Current histopathological staging procedures in colorectal cancer (CRC) depend on midline division of the lymph nodes (LNs) with one section of hematoxylin and eosin staining. Cancer cells outside this transection line may be missed, which could lead to understaging of Union for International Cancer Control Stage II high-risk patients. The one-step nucleic acid amplification (OSNA) assay has emerged as a rapid molecular diagnostic tool for LN metastases detection. It is a molecular technique that can analyze the entire LN tissue using a reverse-transcriptase loop-mediated isothermal amplification reaction to detect tumor-specific cytokeratin 19 mRNA. Our findings suggest that the OSNA assay has a high diagnostic accuracy in detecting metastatic LNs in CRC and a high negative predictive value. OSNA is a standardized, observer-independent technique, which may lead to more accurate staging. It has been suggested that in stage II CRC, the upstaging can reach 25% and these patients can access postoperative adjuvant chemotherapy. Moreover, intraoperative OSNA sentinel node evaluation may allow early CRC to be treated with organ-preserving surgery, while in more advanced-stage disease, a tailored lymphadenectomy can be performed considering the presence of aberrant lymphatic drainage and skip metastases.

Mesorectal excision with lateral lymph node dissection for mid-low rectal cancer with lateral lymph node metastasis: efficacy and prognostic analysis

Background

The aim of this study was to evaluate the efficacy of lateral pelvic lymph node (LPN) dissection (LPND) for rectal cancer patients with LPN metastasis (LPNM) and investigate the impact of LPNM on prognosis.

Methods

One hundred twenty-five matched pairs were selected and divided into the total mesorectal excision (TME) group and TME + LPND group for evaluation after propensity matching.

Results

No significant difference was observed in the 3-year local recurrence rate between the TME group and the TME + LPND group (10.7% vs 8.8%, P = 0.817); however, the rate of distant metastasis after TME + LPND was significantly higher (15.2% vs 7.2%, P = 0.044). When the mesorectal LN and LPN groups were subdivided, 3-year RFS was not significantly different between the internal LPN and N2 groups (57.1% vs. 55.3%, P = 0.613). There was no significant difference in RFS between the external group and the stage IV group (49.1% vs. 22.5%, P = 0.302), but RFS in the former group was significantly worse than that in the N2 group (49.1% vs. 55.3%, P = 0.044).

Conclusion

Although patients with suspected LPNM can achieve satisfactory local control after TME + LPND, systemic metastases are more likely to develop after surgery. Patients limited to internal iliac and obturator LN metastasis appear to achieve a survival benefit from LPND and can be regarded as regional LN metastasis. However, patients with LPNM in the external and common iliac LN metastasis have a poor prognosis that is significantly worse than that of N2 and slightly better than that of stage IV, and LPND should be carefully selected.

Prognostic significance of lateral pelvic lymph node dissection for middle-low rectal cancer patients with lateral pelvic lymph node metastasis: a propensity score matching study

Background

There is still controversy regarding the clinical value and significance of lateral pelvic lymph node (LPN) dissection (LPND). The present study aimed to investigate whether the addition of LPND to total mesorectal excision (TME) confers survival benefits in rectal cancer patients with clinical lateral pelvic node metastasis (LPNM).

Methods

From January 2015 to January 2021, a total of 141 rectal cancer patients with clinical evidence of LPNM who underwent TME + LPND were retrospectively analysed and divided into the LPNM group (n = 29) and the non-LPNM group (n = 112). The LPNM group was further subdivided into a high-risk LPNM group (n = 14) and a low-risk LPNM group (n = 15). Propensity score matching (PSM) was performed to minimize selection bias. The primary outcomes of this study were 3-year overall survival (OS) and disease-free survival (DFS).

Results

Of the 141 patients undergoing LPND, the local recurrence rate of patients with LPNM was significantly higher than that of patients without LPNM both before (27.6% vs. 4.5%, P = 0.001) and after (27.6% vs. 3.4%, P = 0.025) PSM. Multivariate analysis revealed that LPNM was an independent risk factor for not only OS (HR: 3.06; 95% CI, 1.15–8.17; P = 0.025) but also DFS (HR: 2.39; 95% CI, 1.18–4.87; P = 0.016) in patients with LPNM after TME + LPND. When the LPNM group was further subdivided, multivariate logistic regression analysis showed that OS and DFS were significantly better in the low-risk group (obturator/internal iliac artery region and < 2 positive LPNs).

Conclusion

Even after LPND, LPNM patients have a poor prognosis. Moreover, LPNM is an independent poor prognostic factor affecting OS and DFS after TME + LPND. However, LPND appears to confer survival benefits to specific patients with single LPN involvement in the obturator region or internal iliac vessel region. Furthermore, LPND may have no indication in stage IV patients and should be selected carefully.

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.

Lateral lymph node dissection in advanced low rectal cancer treatment

Lateral lymph node (LLN) metastasis is a determinant of local recurrence in advanced low rectal cancer. Lateral lymph node dissection (LLND) is effective in removing metastatic lymph nodes, and has been shown to have a decreased local recurrence rate. However, because of its complexity and complications it induces, there is still tremendous controversy about its usage. Neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME) are recommended as a conventional treatment for advanced rectal cancer. However, LLN metastasis and local recurrence still occur despite nCRT with TME. In Japan, TME with LLND is the standard surgical treatment for Stage II/III of advanced low rectal cancer. Before surgery, a proper evaluation of LLN status should be performed. Laparoscopic LLND and robotic-assisted LLND are useful for this. More research is necessary to improve the oncological outcomes of LLND. In this review, we retrospectively examine previous reports about LLND, aiming to emphasize its application prospects to improve patient survival and life quality.

Prevalence of Metastatic Lateral Lymph Nodes in Asian Patients with Lateral Lymph Node Dissection for Rectal Cancer: A Meta-analysis

Importance

Rectal cancers occupy the eighth position worldwide for new cases and deaths for both men and women. These cancers have a high tendency to form metastases in the mesorectum but also in the lateral lymph nodes. The therapeutic approach for the involved lateral lymph nodes remains controversial.

Objective

We performed a systematic review and meta-analysis to assess the prevalence of metastatic lateral lymph nodes in patients with lateral lymph node dissection (LLND) for rectal cancer, which seems to be a fundamental and necessary criterion to discuss any possible indications for LLND.

Methods

Data sources–study selection–data extraction and synthesis–main outcome and measures. We searched MEDLINE, EMBASE and COCHRANE from November 1, 2018, to November 19, 2018, for studies reporting the presence of metastatic lateral lymph nodes (iliac, obturator and middle sacral nodes) among patients undergoing rectal surgery with LLND. Pooled prevalence values were obtained by random effects models, and the robustness was tested by leave-one-out sensitivity analyses. Heterogeneity was assessed using the Q-test, quantified based on the I2 value and explored by subgroup analyses.

Results

Our final analysis included 31 studies from Asian countries, comprising 7599 patients. The pooled prevalence of metastatic lateral lymph nodes was 17.3% (95% CI: 14.6–20.5). The inter-study variability (heterogeneity) was high (I² = 89%). The pooled prevalence was, however, robust and varied between 16.6% and 17.9% according to leave-one-out sensitivity analysis. The pooled prevalence of metastatic lymph nodes was not significantly different when pooling only studies including patients who received neoadjuvant treatment or those without neoadjuvant treatment (p = 0.44). Meta-regression showed that the pooled prevalence was associated with the sample size of studies (p < 0.05), as the prevalence decreased when the sample size increased.

Conclusion

The pooled prevalence of metastatic lateral lymph nodes was 17.3% among patients who underwent rectal surgery with LLND in Asian countries. Further studies are necessary to determine whether this finding could impact the therapeutic strategy (total mesorectal excision with LLND versus total mesorectal excision with neoadjuvant radiochemotherapy).

Supplementary Information

The online version contains supplementary material available at(10.1007/s00268-021-05956-1)

The advantage of one-step nucleic acid amplification for the diagnosis of lymph node metastasis in colorectal cancer patients

Generally, the postoperative examination of lymph nodes (LNs) is based on a microscopic examination of one hematoxylin and eosin (HE)-stained slide; however, an examination of only one part of the LN might lead to incorrect staging of the tumor due to tissue allocation bias. Although multilevel sectioning and the use of immunohistochemistry (IHC) have improved the detection of micrometastases in LNs, this approach is laborious, time-consuming, and costly. A novel molecular technique for the detection of LN metastases of tumors, called one-step nucleic acid amplification (OSNA), is a rapid and semi-quantitative examination quantifying the number of cytokeratin 19 (CK-19) mRNA copies derived from a tumor. OSNA is already in clinical use for the diagnosis of LN metastasis in breast cancer patients; however, the use of OSNA is under investigation with promising results for colorectal cancer (CRC). The present review assessed recent studies on OSNA vs a histopathological examination and its implications for CRC staging and treatment. A total of 16 studies of OSNA in CRC yielded by a PubMed search were reviewed. Among them, seven studies evaluating the diagnostic performance revealed that OSNA had a high specificity (96.8%), high concordance rate (96.0%), and negative predictive value (98.6%) in a pooled assessment. In addition, four studies examining the utility of OSNA in sentinel LNs (SLNs) and two studies focusing on upstaging in pathologically node-negative CRC patients were also reviewed. Multicenter prospective studies with a large cohort of CRC patients are warranted to reveal the benefits of OSNA in the future.

Prognostic impact of the number of lateral pelvic lymph node metastases on rectal cancer

BACKGROUND

This study aimed to clarify the number of lateral pelvic lymph node metastases of colorectal cancer for which prognosis could be improved by dissection.

METHODS

We analysed the data of 30 patients with lateral pelvic lymph node metastases of rectal cancer that underwent a total mesorectal excision with lateral pelvic lymph node dissection at our institute from 1986 to 2016. We performed survival analysis on the number of lateral pelvic lymph node metastases in each of these patients and identified an optimal cut-off point of the number of lateral pelvic lymph node metastases that would predict recurrence-free survival using the receiver operating characteristic curves and an Akaike information criterion value.

RESULTS

The 5-year recurrence-free survival and overall survival of patients with one or two lateral pelvic lymph node metastases were significantly better than that of those with three or more (5-year recurrence-free survival, 63.3 vs. 0.0%, respectively; hazard ratio, 0.23; 95% CI, 0.07-0.72; P = 0.0124) (5-year overall survival, 68.2 vs. 15.6%, respectively; hazard ratio, 0.29; 95% CI, 0.09-0.92; P = 0.0300). All of the metastatic lateral pelvic lymph nodes in the group with one or two lateral pelvic lymph node metastases were restricted to the internal iliac artery or obturator nerve regions.

CONCLUSIONS

The cut-off number of lateral pelvic lymph node metastases in the internal iliac artery or obturator nerve regions of colorectal cancer cases in whom prognosis was improved by lateral pelvic lymph node dissection was 2; patients who had <3 lateral pelvic lymph node metastases had better prognoses than those with ≥3 lateral pelvic lymph node metastases.

Study of therapeutic results, lymph node ratio, short-term and long-term complications of lateral lymph node dissection in rectal cancer patients

Objectives

This study aimed to assess disease free survival, lymph node ratio (LNR) and complication rate among advanced mid to low rectal cancer patients (stage 2-3) who underwent total mesorectal excision (TME) and lateral lymph node dissection (LLND) at the Iran Cancer Institute in 2016-2018.

Material and Methods

The study was carried out on 32 patients treated by curative surgery and lateral lymph node dissection at the Iran Cancer Institute from 2016 March to 2018 March. Chi-square test was used to assess the distribution of dichotomous clinical outcomes by sex. We also used Breslow test in Kaplan-Meier approach to estimate 1-year disease free survival and corresponding 95% confidence intervals (CI).

Results

Of the 279 dissected lymph nodes by TME, 42 nodes (in mesorectal) and of the 232 dissected lymph nodes by LLND, 7 nodes (in iliac, para-iliac and obturator) were positive for metastasis. Higher local recurrence was observed in men (three patients) compared to women (one patient) which was not statistically significant (p= 0.878). We also observed higher 1-year disease free survival rate in women (1-year disease free survival= 93.3%) compared to men (1-year disease free survival= 82.4%), which also was not statistically significant (p= 0.356). 1-year disease free survival rate in patient with negative lymph nodes was 95.5% while respective number in patients with positive lymph nodes was 70% (p= 0.047).

Conclusion

TME with LLND could prolong survival and reduce local recurrence in patients with advanced low rectal cancer. However, large-scale clinical trials are required to evaluate such procedure as a standard in Iran.

Predictive factors of disease-free survival after complete pathological response to neoadjuvant radiotherapy for rectal adenocarcinoma: retrospective case series

Background

Many data suggest that patients with low rectal adenocarcinoma who achieved ypT0N0 status have improved survival and disease-free survival (DFS) compared to all other stages however only few data are available regarding the specific prognosis factors of this subgroup. This study aimed to evaluate predictive factors for disease free survival after complete pathological response (CPR) in cases of low rectal adenocarcinoma.

Materials and methods

From January 2005 to December 2013, all patients with low rectal adenocarcinoma who underwent neoadjuvant chemoradiotherapy followed by total mesorectal excision and achieved CPR were included at 7 Moroccan and 1 Algerian centres. Predictive factors for disease-free survival were analysed by uni and multivariate analysis.

Results

Eigthy-four (12.1%) patients achieved a CPR (ypT0N0). Multivariate analysis revealed that both poorly differentiated tumors (OR, 9.23; 95 CI 1.35–62.82; P = 0.023) and the occurrence of perineal sepsis (OR, 13.51; 95 CI 1.96–93.12; P = 0.008) were independently associated with impaired DFS.

Conclusions

Patients with low rectal cancer who exhibited a CPR after neoadjuvant therapy have good prognoses; however, the occurrence of perineal sepsis and/or poor initial differentiation may be associated with impaired DFS in these patients.

Trial registration: The study was retrospectively registered the 28th July 2018 in ClinicalTrials.gov register with the reference NCT03601689.

Lateral Nodal Features on Restaging Magnetic Resonance Imaging Associated With Lateral Local Recurrence in Low Rectal Cancer After Neoadjuvant Chemoradiotherapy or Radiotherapy

Importance

Previously, it was shown in patients with low rectal cancer that a short-axis (SA) lateral node size of 7 mm or greater on primary magnetic resonance imaging (MRI) resulted in a high lateral local recurrence (LLR) rate after chemoradiotherapy or radiotherapy ([C]RT) with total mesorectal excision (TME) and that this risk was lowered by a lateral lymph node dissection (LLND). The role of restaging MRI after (C)RT with regard to LLR risk and which specific patients might benefit from an LLND is not fully understood.

Objective

To determine the factors on primary and restaging MRI that are associated with LLR in low rectal cancer after (C)RT and to formulate specific guidelines on which patients might benefit from an LLND.

Design, Setting, and Participants

In this retrospective, multicenter, pooled cohort study, patients who underwent surgery for cT3 or cT4 low rectal cancer with a curative intent from 12 centers in 7 countries from January 2009 to December 2013 were included. All patients' MRIs were rereviewed according to a standardized protocol, with specific attention to lateral nodal features. The original cohort included 1216 patients. For this study, patients who underwent (C)RT and had a restaging MRI were selected, leaving 741 for analyses across 10 institutions, including 651 who underwent (C)RT with TME and 90 who underwent (C)RT with TME and LLND.

Main Outcomes and Measures

The main purpose was to identify the factors on primary and restaging MRI associated with LLR after (C)RT with TME. Whether high-risk patients might benefit in terms of LLR reduction from an LLND was also studied.

Results

Of the 741 included patients, 480 (64.8%) were male, and the mean (SD) age was 60.4 (12.0) years. An SA lateral node size of 7 mm or greater on primary MRI resulted in a 5-year LLR rate of 17.9% after (C)RT with TME. At 3 years, there were no LLRs in 28 patients (29.2%) with lateral nodes that were 4 mm or less on restaging MRI. Nodes that were 7 mm or greater on primary MRI and greater than 4 mm on restaging MRI in the internal iliac compartment resulted in a 5-year LLR rate of 52.3%, significantly higher compared with nodes in the obturator compartment of that size (9.5%; hazard ratio, 5.8; 95% CI, 1.6-21.3; P = .003). Compared with (C)RT with TME alone, treatment with (C)RT with TME and LLND in these unresponsive internal nodes resulted in a significantly lower LLR rate of 8.7% (hazard ratio, 6.2; 95% CI, 1.4-28.5; P = .007).

Conclusions and Relevance

Restaging MRI is important in clinical decision making in lateral nodal disease. In patients with shrinkage of lateral nodes from an SA node size of 7 mm or greater on primary MRI to an SA node size of 4 mm or less on restaging MRI, which occurs in about 30% of cases, LLND can be avoided. However, persistently enlarged nodes in the internal iliac compartment indicate an extremely high risk of LLR, and an LLND lowered LLR in these cases.

Sentinel Lymph Node Analysis in Colorectal Cancer Patients Using One-Step Nucleic Acid Amplification in Combination With Fluorescence and Indocyanine Green

PURPOSE

Analysis of the sentinel lymph node (SLN) in colorectal cancer (CRC) patients was proposed for more accurate staging and tailored lymphadenectomy. The aim of this study was to assess the ability to predict lymph node (LN) involvement through analysis of the SLN with a one-step nucleic acid (OSNA) technique in combination with peritumoral injection of indocyanine green (ICG) and near-infrared (NIR) lymphangiography in CRC patients.

METHODS

A total of 34 patients were enrolled. Overall, 51 LNs were analyzed with OSNA. LNs of 17 patients (50%) were examined simultaneously with hematoxylin and eosin (H&E) and OSNA.

RESULTS

SLN analysis of 17 patients examined with H&E and OSNA revealed that OSNA had a higher sensitivity (1 vs. 0.55), higher negative predictive value (1 vs. 0.66) and higher accuracy (100% vs. 76.4%) in predicting LN involvement. Overall, OSNA showed a sensitivity of 0.69, specificity of 1, accuracy of 88.2%, and stage migration of 8.8%. Compared to those who were OSNA (-), OSNA (+) patients had a greater number of LN metastases (4.8 vs. 0.16, P = 0.04), higher G3 rate (44.4% vs. 4%, P = 0.01), more advanced stage of disease (stage III: 77.8% vs. 16%; P = 0.00) and were more rapidly subjected to adjuvant chemotherapy (39.1 days vs. 50.2 days, P = 0.01).

CONCLUSION

SLN analysis with OSNA in combination with ICG-NIR lymphangiography is feasible and can detect LN involvement in CRC patients. Furthermore, it allows for more accurate staging reducing the delay between surgery and adjuvant chemotherapy.

Inspection of Perirectal Lymph Nodes by One-Step Nucleic Acid Amplification Predicts Lateral Lymph Node Metastasis in Advanced Rectal Cancer

BACKGROUND

Lateral lymph node dissection (LLND) is performed for advanced rectal cancers in Japan; however, it can cause sexual and urinary dysfunction. The incidence of lateral LN metastasis is estimated at 7-13.9%; therefore, excessive rectal surgery with LLND should be avoided, especially for prophylactic purposes. To identify the patients who require LLND, we examined metastases in perirectal LNs by using a one-step nucleic acid amplification (OSNA) assay to predict lateral LN metastases.

METHODS

Twenty-five patients who underwent surgery with bilateral LN dissection due to T3-T4 rectal cancers were prospectively included in this study. Twenty-two patients (88.0%) received preoperative chemotherapy. Among 1052 LNs from 25 patients (median 40 per case), 135 perirectal LNs (median 6 per patient) were divided into three pieces and analyzed by OSNA, reverse transcriptase-polymerase chain reaction for carcinoembryonic antigen mRNA, and pathological examination after surgery. These results were compared with the pathological diagnosis of lateral LNs.

RESULTS

Lateral LN metastases were present in 4 of 25 patients (16.0%). All of these patients were positive by OSNA for perirectal LN metastases. The OSNA assay had a sensitivity of 100%, specificity of 86%, positive predictive value of 57%, and negative predictive value (NPV) of 100% for predicting lateral LN metastases.

CONCLUSIONS

The findings from this prospective study suggest that the OSNA assay of perirectal LNs may be useful for determining when LLND is necessary because of its high NPV, even in patients treated with preoperative chemotherapy.