Rectal Cancer Nodes Research Articles

New morphological risk factors for metastasis to regional lymph nodes in rectal cancer with invasion into the submucosa

AIM to assess prognostic significance of pathologic features of T1 rectal carcinoma in relation to regional lymph nodes involvement (N+).MATERIAL AND METHODS: surgical specimens (n = 66) from rectal resection for carcinoma pT1 were investigated. Following prognosticators were evaluated: depth of submucosal invasion, grade of differentiation, lymphovascular invasion (LVI), tumor budding (Bd), poorly differentiated clusters (PDC) of tumor and rupture of cancer glands (CGR).RESULTS: lymph nodes metastases were found in 13 (19.7%) specimens. LVI was associated lymphatic spread in great possibility OR 38.0 95% CI 2.1-670 (p < 0.0001). Tumor budding of high grade (Bd3) OR 6.2 95% CI 1.2-31 (p < 0.0001) and poorly differentiated clusters (p = 0,03) also increased risk of lymph node metastases. Depth of submucosal invasion, grade of differentiation, and rupture of cancer glands failed to demonstrate significant association with N+. Logistic regression analysis allowed to determine LVI as independent prognostic factor of lymph node tumor involvement.CONCLUSION: lymphovascular invasion, tumor budding and poorly differentiated clusters of tumor are risk factors of T1 rectal carcinoma lymph node metastases.

ASO Author Reflection: Lateral Pelvic Lymph Nodes in Rectal Cancer-Not All Are Created Equal.

ASO Author Reflection: Lateral Pelvic Lymph Nodes in Rectal Cancer-Not All Are Created Equal.

From "East vs West" towards international multidisciplinary collaboration: An appraisal of lateral lymph nodes in rectal cancer.

Western and Eastern practices have traditionally differed in their approach to treating lateral lymph nodes in rectal cancer. While Western clinicians have primarily favored neoadjuvant (chemo)radiotherapy to sterilize lateral compartments, Eastern physicians have often opted for the surgical removed of lymphatic tissue with a lateral lymph node dissection without neoadjuvant treatment. The literature suggests similar oncological outcomes for these two separate techniques, while tangible differences exist. The combination of these paradigms may be beneficial in reducing overall morbidity while sustaining low recurrence rates. This article considers traditional Eastern and Western perspectives, discusses nodal features important for predicting malignancy and attempts to stimulate international, multidisciplinary consensus and collaboration.

Apparent diffusion coefficient cannot discriminate metastatic and non-metastatic lymph nodes in rectal cancer: a meta-analysis

BackgroundOur aim was to provide data regarding use of diffusion-weighted imaging (DWI) for distinguishing metastatic and non-metastatic lymph nodes (LN) in rectal cancer.MethodsMEDLINE library, EMBASE, and SCOPUS database were screened for associations between DWI and metastatic and non-metastatic LN in rectal cancer up to February 2021. Overall, 9 studies were included into the analysis. Number, mean value, and standard deviation of DWI parameters including apparent diffusion coefficient (ADC) values of metastatic and non-metastatic LN were extracted from the literature. The methodological quality of the studies was investigated according to the QUADAS-2 assessment. The meta-analysis was undertaken by using RevMan 5.3 software. DerSimonian, and Laird random-effects models with inverse-variance weights were used to account the heterogeneity between the studies. Mean DWI values including 95% confidence intervals were calculated for metastatic and non-metastatic LN.ResultsADC values were reported for 1376 LN, 623 (45.3%) metastatic LN, and 754 (54.7%) non-metastatic LN. The calculated mean ADC value (× 10−3 mm2/s) of metastatic LN was 1.05, 95%CI (0.94, 1.15). The calculated mean ADC value of the non-metastatic LN was 1.17, 95%CI (1.01, 1.33). The calculated sensitivity and specificity were 0.81, 95%CI (0.74, 0.89) and 0.67, 95%CI (0.54, 0.79).ConclusionNo reliable ADC threshold can be recommended for distinguishing of metastatic and non-metastatic LN in rectal cancer.

USPIO-enhanced MRI of lymph nodes in rectal cancer: A node-to-node comparison with histopathology

PurposeTo evaluate the initial results of predicting lymph node metastasis in rectal cancer patients detected in-vivo with USPIO-enhanced MRI at 3 T compared on a node-to-node basis with histopathology. MethodsTen rectal cancer patients of all clinical stages were prospectively included for an in-vivo 0.85 mm3 isotropic 3D MRI after infusion of Ferumoxtran-10. The surgical specimens were examined ex-vivo with an 0.29 mm3 isotropic MRI examination. Two radiologists evaluated in-vivo MR images with a classification scheme to predict lymph node status. Ex-vivo MRI was used for MR-guided pathology and served as a key link between in-vivo MRI and final histopathology for the node-to-node analysis. Results138 lymph nodes were detected by reader 1 and 255 by reader 2 (p = 0.005) on in-vivo MRI with a median size of 2.6 and 2.4 mm, respectively. Lymph nodes were classified with substantial inter-reader agreement (κ = 0.73). Node-to-node comparison was possible for 55 lymph nodes (median size 3.2 mm; range 1.2–12.3), of which 6 were metastatic on pathology. Low true-positive rates (3/26, 11 % for both readers) and high true negative rates were achieved (14/17, 82 %; 19/22, 86 %). Pathological re-evaluations of 20 lymph nodes with high signal intensity on USPIO-enhanced MRI without lymph node metastases (false positives) did not reveal tumor metastasis but showed benign lymph node tissue with reactive follicles. ConclusionsHigh resolution MRI visualizes a large number of mesorectal lymph nodes. USPIO-enhanced MRI was not accurate for characterizing small benign versus small tumoral lymph nodes in rectal cancer patients. Suspicious nodes on in-vivo MRI occur as inflammatory as well as metastatic nodes.

MRI-detected extramural vascular invasion potentiates the risk for pathological metastasis to the lateral lymph nodes in rectal cancer

Multidisciplinary treatment for locally advanced rectal cancer requires an accurate assessment of the risk of metastasis to the lateral lymph nodes (LNs). We herein aimed to stratify the risk of pathological metastasis to lateral LNs based on the preoperatively detected malignant features. All patients with rectal cancer who underwent surgery from January 2016 to July 2020 were identified. We recorded the TNM factors; perirectal and lateral LN sizes; and MRI findings, including mesorectal fascia involvement, extramural vascular invasion (EMVI), tumor site, and tumor distance from the anal verge. 101 patients underwent rectal resection with lateral lymph node dissection, of whom 16 (15.8%) exhibited pathological metastases to the lateral LNs. Univariate analyses demonstrated that lateral LN metastasis was significantly correlated with mrEMVI positivity (p = 0.0023) and a baseline lateral LN short-axis length of ≥ 5mm (p < 0.0001). These significant associations were confirmed by a multivariate analysis (p = 0.0254 and 0.0027, respectively). The lateral LN metastasis rate was as high as 44% in cases bearing both risk factors, compared to 0% in cases lacking both risk factors. The results elucidated in this study may contribute to risk stratification, which can be used when determining the indications for lateral lymph node dissection.

Feasibility and reproducibility of T2 mapping and DWI for identifying malignant lymph nodes in rectal cancer.

To evaluate the diagnostic value and reproducibility of T2 mapping versus apparent diffusion coefficients (ADC) for identifying malignant lymph nodes in patients with non-mucinous rectal adenocarcinoma. High-resolution magnetic resonance imaging, diffusion-weighted imaging, and T2 mapping were performed on patients with suspected metastatic lymph nodes in the mesorectum or around the superior rectal artery with a short-axis diameter of 4-10 mm. The T2 and ADC values of pathology-confirmed metastatic versus non-metastatic lymph nodes were compared using the independent-samples t test and receiver operating characteristic curves. Intra- and inter-observer reproducibility were tested. The cutoff value for T2 relaxation time was determined. In total, 67 lymph nodes underwent histological analysis, with 24 in the non-metastatic and 43 in the metastatic groups. Intra- and inter-observer agreements for T2 values were 0.999 and 0.998, respectively, which were higher than the ADC values of 0.924 and 0.844, respectively. The mean T2 and ADC values for metastatic lymph nodes (65 ± 7.8 ms and 1.17 ± 0.16 × 10-3 mm2/s, respectively) were significantly lower than for benign lymph nodes(83 ± 5.7 ms and 1.29 ± 0.15 × 10-3 mm2/s, respectively). T2 values had a higher AUC value of 0.990 than the AUC value for ADC of 0.729. With a cutoff value of 77 ms, sensitivity and specificity for T2 values were 95% and 96%, respectively. T2 mapping had higher diagnostic efficacy and reproducibility than ADC and may be useful in differentiating metastatic from non-metastatic lymph nodes in rectal cancer. • Mean T2 values were significantly shorter for malignant versus benign LNs in patients with non-mucinous rectal adenocarcinoma. • The diagnostic efficacy and reproducibility of T2 values were excellent and superior to ADC values.

A deep learning nomogram kit for predicting metastatic lymph nodes in rectal cancer.

BackgroundPreoperative diagnoses of metastatic lymph nodes (LNs) by the most advanced deep learning technology of Faster Region‐based Convolutional Neural Network (Faster R‐CNN) have not yet been reported.Materials and MethodsIn total, 545 patients with pathologically confirmed rectal cancer between January 2016 and March 2019 were included and were randomly allocated with a split ratio of 2:1 to the training and validation sets, respectively. The MRI images for metastatic LNs were evaluated by Faster R‐CNN. Multivariate regression analyses were used to develop the predictive models. Faster R‐CNN nomograms were constructed based on the multivariate analyses in the training sets and were validated in the validation sets.ResultsThe Faster R‐CNN nomogram for predicting metastatic LN status contained predictors of age, metastatic LNs by Faster R‐CNN and differentiation degrees of tumors, with areas under the curves (AUCs) of 0.862 (95% CI: 0.816‐0.909) and 0.920 (95% CI: 0.876‐0.964) in the training and validation sets, respectively. The Faster R‐CNN nomogram for predicting LN metastasis degree contained predictors of metastatic LNs by Faster R‐CNN and differentiation degrees of tumors, with AUCs of 0.859 (95% CI: 0.804‐0.913) and 0.886 (95% CI: 0.822‐0.950) in the training and validation sets, respectively. Calibration plots and decision curve analyses demonstrated good calibrations and clinical utilities. The two nomograms were used jointly as a kit for predicting metastatic LNs.ConclusionThe Faster R‐CNN nomogram kit exhibits excellent performance in discrimination, calibration, and clinical utility and is convenient and reliable for predicting metastatic LNs preoperatively.Clinical trial registration: ChiCTR‐DDD‐17013842.

Utility of texture analysis on T2-weighted MR for differentiating tumor deposits from mesorectal nodes in rectal cancer patients, in a retrospective cohort.

The purpose of the study was to evaluate the utility of MR texture analysis for differentiating tumor deposits from mesorectal nodes in rectal cancer. Pretreatment MRI of 40 patients performed between 2006 and 2018 with pathologically proven tumor deposits and/or malignant nodes in the setting of rectal cancer were retrospectively reviewed. In total, 25 tumor deposits (TDs) and 71 positive lymph nodes (LNs) were analyzed for morphological and first-order texture analysis features on T2-weighted axial images. MR morphological features (lesion shape, size, signal heterogeneity, contrast enhancement) were analyzed and agreed in consensus by two experienced radiologists followed by assessmentwith Fisher's exact test. Texture analysis of the lesions was performed using TexRAD, a proprietary software algorithm. First-order texture analysis features (mean, standard deviation, skewness, entropy, kurtosis, MPP) were obtained after applying spatial scaling filters (SSF; 0, 2, 3, 4, 5, 6). Univariate analysis was performed with non-parametric Mann-Whitney U test. The results of univariate analysis were reassessed with generalized estimating equations followed by multivariate analysis. Using histopathology as a gold standard, diagnostic accuracy was assessed by obtaining area under the receiver operating curve. MR morphological parameter, lesion shape was a strong discriminator between TDs and LNs with a p value of 0.02 (AUC: 0.76, 95% CI of 0.66 to 0.84, SE: 0.06) and sensitivity, specificity of 90% and 68%, respectively. Skewness extracted at fine filter (SSF-2) was the only significant texture analysis parameter for distinguishing TDs from LNs with p value of 0.03 (AUC: 0.70, 95% CI of 0.59 to 0.79, SE: 0.06) and sensitivity, specificity of 70% and 72%, respectively. When lesion shape and skewness-2 were combined into a single model, the diagnostic accuracy was improved with AUC of 0.82 (SE: 0.05, 95% CI of 0.72 to 0.88 with p value of < 0.01). This model also showed a high sensitivity of 91% with specificity of 68%. Lesion shape on MR can be a useful predictor for distinguishing TDs from positive LNs in rectal cancer patients. When interpreted along with MR texture parameter of skewness, accuracy is further improved.

Incidence and treatment of positive pelvic sidewall lymph nodes in patients with rectal cancer.

The involvement of pelvic sidewall (PSW) lymph nodes in rectal cancer is a marker of locally advanced disease and poor prognosis. Eastern countries generally advocate lateral lymph node dissection (LLND) over the Western approach of neoadjuvant chemoradiotherapy and more limited surgery. The aim of this study was to evaluate how these advanced cancers were treated in three UK Health Boards. This was a retrospective review of three colorectal multidisciplinary team meetings from 2008 to 2016. All patients with rectal cancer and suspicious PSW lymph nodes on pretreatment MRI were included. There were 153 (6.2%) patients who met the inclusion criteria from a total of 2461 diagnosed rectal cancers. There was significant variability between the three centres with surgical intervention ranging from 59.2% to 84.4%, P=0.015. There were 81 patients who had neoadjuvant chemoradiotherapy prior to surgery; of these 67 (82.7%) still had positive PSW nodes on the restaging MRI, but only 13 (19.4%) had LLND. There was no difference in local recurrence (15.3% vs 11.8%, P=0.66), 5-year overall survival (69.2% vs 80.1%, P=0.16) or 5-year disease-free survival (69.2% vs 79.4%, P=0.72) between patients having LLND and those receiving standard neoadjuvant treatment followed by total mesorectal excision surgery. This study has demonstrated that rectal cancer patients with PSW positive nodal disease have advanced disease, mostly of the lower rectum, and receive a highly heterogeneous spectrum of therapies, even within a relatively small geographical area. Greater accuracy in our preoperative staging is needed to select those patients who will benefit from LLND surgery.

Lymph Node Positivity in T1/T2 Rectal Cancer: a Word of Caution in an Era of Increased Incidence and Changing Biology for Rectal Cancer

BackgroundThe evaluation of lymph nodes in rectal cancer dictates treatment. The goals of this study are to characterize the contemporary rate of lymph node metastasis in early stage rectal cancer and to re-investigate histologic factors that predict positive lymph nodes. Materials and MethodsUsing the National Cancer Database, we identified patients with clinical stage I rectal adenocarcinoma. Multivariable logistic regression was used to determine risk factors for lymph node positivity. Results12.2% of patients with T1 tumors and 18.0% of patients with T2 tumors had positive lymph nodes. For T1 tumors, positive lymph nodes were present in 9.3% with neither poor differentiation nor lymphovascular invasion (LVI), 17.3% with poor differentiation alone, 34.7% with LVI alone, and 45.0% with both poor differentiation and LVI. For T2 tumors, positive lymph nodes were present in 11.7% with neither poor differentiation nor LVI, 25.3% with poor differentiation alone, 47.3% with LVI alone, and 41.5% with both poor differentiation and LVI. LVI was an independent predictor of positive lymph nodes (OR;4.75,95%CI;3.17–7.11,p < 0.001) for T1 and (OR;6.20,95%CI;4.53–8.51,p < 0.001) T2 tumors. ConclusionsT1/T2 tumors have higher rates of positive lymph nodes when poor differentiation and LVI are present. These results should be taken into consideration prior to surgical treatment.

Effect and Safety of Radiation Therapy Boost to Extramesorectal Lymph Nodes in Rectal Cancer

PurposeIn rectal cancer, the presence of extramesorectal/lateral pelvic lymph node (LPN) is associated with higher risk of locoregional and distant recurrences. LPNs are not typically resected during a standard total mesorectal excision (TME) procedure, and the optimal management for these patients is controversial. We assessed the safety and efficacy of adding a radiation therapy boost to clinically positive LPN during neoadjuvant chemoradiation therapy for rectal cancer. Methods and MaterialsWe analyzed nonmetastatic, lymph node positive rectal adenocarcinoma patients treated with neoadjuvant chemoradiation therapy followed by TME between May 2011 and February 2018. Patients without LPN involvement received external beam radiation therapy (45 Gy in 25 fractions) to the primary tumor and regional draining lymph node basins followed by a boost (5.4 Gy in 3 fractions) to gross disease. Patients with clinically positive LPN that would not be removed during TME received an additional boost (up to a total dose between 54.0 and 59.4 Gy) to the involved LPNs. We compared locoregional control, overall survival, progression-free survival, and treatment-related toxicity between these 2 groups. ResultsFifty-three patients were included in this analysis with median follow-up of 30.6 months for the LPN– group (n = 41) and 19.9 months for the LPN+ group (n = 12). There was no difference in 3-year overall survival (90.04% vs 83.33%, P = .890) and progression-free survival (80.12% vs 80.21%, P = .529) between the 2 groups. We did not observe any LPN recurrences. There were no differences in rates of acute grade 3+ or chronic toxicities. ConclusionsDespite the well-documented negative prognostic effect of LPN metastasis, we observed promising outcomes for LPN+ patients treated with an additional radiation boost. Our results suggest that radiation therapy boost to clinically involved, unresected LPN is an effective treatment approach with limited toxicity. Additional studies are needed to optimize treatment strategies for this unique patient subset.

The significance of lymph node yield in rectal cancer after neoadjuvant chemotherapy

Neoadjuvant therapy has become an indispensable part of the treatment in locally advanced mild-low rectal cancer. Neoadjuvant therapy can cause the regression of the tumor body as well as drainage lymph nodes, which may influence the size, number, and metastatic status of the lymph nodes. In clinical practice, the total number of lymph nodes detected in rectal cancer treated with neoadjuvant therapy were significantly decreased, making it difficult to meet the standard of the NCCN guideline that at least 12 regional lymph nodes should be harvested. The optimal detection of yielded lymph nodes in rectal cancer is essential for accurate staging, response assessment, and adjuvant treatment decision. The lymph node diameter is significantly reduced after neoadjuvant therapy in locally advanced rectal cancer. In general, the number of detected lymph nodes is significantly reduced without additional pathological examination. The detected lymph nodes would increase by deliberate pathological examination, improvement of the detection method, or using a lymph node tracer. However, whether the number of detected lymph nodes is still needed to meet the requirements of the NCCN guideline, and the relationship between the number of detected lymph nodes and the prognosis are still controversial. At present, the number of negative lymph nodes, LNR, LODDS, etc. can be also used to predict prognosis in addition to ypN staging. For patients with ypN0 and ypN+ stage, different evaluation methods can be selected. For patients with ypN0, the number of detected lymph nodes still has important clinical significance for the prognosis and treatment decision. This article will introduce the related issues, and provide more evidence-based diagnosis and treatment practice.

Significance, diagnosis and treatment of lateral lymph nodes in rectal cancer: A systematic review

IntroductionPatients with low rectal cancer are at risk for lateral lymph node metastasis (LLNM). Neoadjuvant chemoradiotherapy (CRT) is used to eradicate LLNM in the West, whereas in Japan the addition of lateral lymph node dissection (LLND) to total mesorectal excision (TME) is performed. A systematic review was conducted to assess incidence, location, risk factors and diagnosis of LLNM and lateral lymph node (LLN) treatment outcomes. MethodThe Medline, Embase and Cochrane databases were searched for English-language articles pertaining to LLNs in rectal cancer. Results242 studies were identified and 15 prospective studies selected for qualitative analysis. LLNM was detected in 7–40% of patients who underwent LLND, and lower incidence occurred in patients without preoperative suspicion of LLNM. LLNs located along the middle rectal artery were most common. LLNM was associated with female sex, advanced T stage and positive mesorectal nodes. LLN short-axis diameter of ≥10 mm on preoperative imaging appeared to predict LLNM after neoadjuvant CRT. The addition of LLND to TME seemed to decrease LR and improve survival rates, with comparable results seen for CRT. LLND appeared to be associated with longer operation time, greater blood loss and increased risk of sexual and urinary dysfunction. ConclusionLLND could be advantageous for patients with suspected LLNM, but associated morbidities need to be considered. Further studies are needed to improve preoperative identification of LLNs and to determine how to manage persistent enlarged LLNs after CRT. Furthermore, the applicability of LLND in a Western population needs to be investigated.

Does a fine line exist between regional and metastatic pelvic lymph nodes in rectal cancer-striking discordance between national guidelines and treatment recommendations by US radiation oncologists.

Management of rectal cancer with involved lateral pelvic lymph nodes (LPLNs) at the time of diagnosis-the stage we refer institutionally to as Stage 3.5-is controversial. The American Joint Committee on Cancer's 7th edition classifies internal iliac lymph nodes (LNs) as regional (Stage III), but both external and common iliac LNs as metastatic (Stage IV). However, in many Asian countries all LPLNs are considered regional and patients are treated with curative intent, with literature supporting improved outcomes with LPLN dissection. Management patterns of these patients by US radiation oncologists (ROs) are unknown. American ROs completed an anonymous institutional review board-approved online questionnaire regarding rectal cancer management. Among the 220 completed responses, 45% treat more than 10 patients annually and 39% work in academia. We found 10.5% and 34.2% recommend biopsy of clinically involved internal and common iliac LNs, respectively. The vast majority of responders-98.6% and 94.5%-treat involved internal and common iliac LNs with curative intent, respectively. Respondents recommend treatment intensification to involved internal iliac LNs by dissection of the nodal basin (88.2%) and radiation therapy (RT) boost (59.1%), and treatment intensification to involved common iliac LNs by LN dissection (76.4%) and RT boost (63.6%). Our analysis reveals that the vast majority of US ROs approach patients with involved LPLNs, both regional (internal iliac) and metastatic (common iliac), with curative intent. They recommend treatment intensification with surgical resection and/or RT boost to involved nodes. Prospective clinical trials need to determine the appropriate management of patients with Stage 3.5 rectal cancer.

Fat-suppressed gadolinium-enhanced isotropic high-resolution 3D-GRE-T1WI for predicting small node metastases in patients with rectal cancer

BackgroundTo investigate the application value of fat-suppressed gadolinium-enhanced isotropic high-resolution 3D-GRE-T1WI in regional nodes with different short-axis diameter ranges in rectal cancer, especially in nodes ≤5 mm.MethodsPatients with rectal adenocarcinoma confirmed by postoperative histopathology were included, and all the patients underwent preoperative 3.0 T rectal magnetic resonance imaging (MRI) and total mesorectal excision (TME) within 2 weeks after an MR scan. The harvested nodes from specimens were matched with nodes in the field of view (FOV) of images for a node-by-node evaluation. The maximum short-axis diameters of all the visible nodes in the FOV of images were measured by a radiologist; the morphological and enhancement characteristics of these nodes were also independently evaluated by two radiologists. The χ2 test was used to evaluate differences in morphological and enhancement characteristics between benign and malignant nodes. The enhancement characteristics were further compared between benign and malignant nodes with different short-axis diameter ranges using the χ2 test. Kappa statistics were used to describe interobserver agreement.ResultsA total of 441 nodes from 70 enrolled patients were included in the evaluation, of which 111 nodes were metastatic. Approximately 85.5 and 95.6% of benign nodes were found to have obvious enhancement and homogeneous or mild-heterogeneous enhancement, respectively, whereas approximately 89.2 and 85.1% of malignant nodes showed moderate or mild enhancement and obvious-heterogeneous or rim-like enhancement, respectively. The area under the receiver operating characteristic (ROC) curve (AUC) values of the enhancement degree for identifying the overall nodal status, nodes ≤5 mm and nodes > 5 mm and ≤ 10 mm were 0.887, 0.859 and 0.766 for radiologist 1 and 0.892, 0.823 and 0.774 for radiologist 2, respectively. The AUCs of enhancement homogeneity were 0.940, 0.928 and 0.864 for radiologist 1 and 0.944, 0.938 and 0.842 for radiologist 2, respectively. Nodal border and signal homogeneity were also of certain value in distinguishing metastatic nodes.ConclusionsEnhancement characteristics based on fat-suppressed gadolinium-enhanced isotropic high-resolution 3D-GRE-T1WI were helpful for diagnosing metastatic nodes in rectal cancer and were a reliable indicator for nodes ≤5 mm.

The fine line between regional and metastatic pelvic lymph nodes in rectal cancer: Patterns of care among U.S. radiation oncologists.

758 Background: Management of rectal cancer with involved lateral pelvic lymph nodes (LPLNs) at the time of diagnosis – the stage we refer institutionally to as Stage 3.5 – is controversial. Asian investigators consider internal, external and common iliac lymph nodes (LNs) as regional disease and treat these patients (pts) with curative intent, which often includes LPLN dissection. Conversely, AJCC 7thedition classifies internal iliac LNs as regional, whereas both external and common iliac LNs as metastatic. NCCN guidelines recommend definitive trimodality therapy for Stage III rectal cancer, and palliative chemotherapy for Stage IV disease. Radiation oncologists (ROs) in the U.S. irradiate iliac LNs in the setting of other pelvic malignancies, but it is unknown how they approach newly diagnosed rectal cancer pts with LPLN involvement. Methods: We conducted an anonymous IRB-approved online survey of practicing U.S. ROs, probing their approach to management of rectal cancer pts with clinically involved LPLNs. Results: We received 220 responses. Among the responders, 85 are academically affiliated and the majority self-declared a specialization in treating GI malignancies, with 98 seeing more than 10 rectal cancer pts annually. Among respondents, 10.5% and 34.2% recommend biopsy of clinically involved internal and common iliac LNs, respectively. The vast majority of responders – 98.6% and 94.5% – treat involved internal and common iliac LNs with curative intent, respectively. Respondents recommend treatment intensification to involved internal iliac LNs by dissection of the nodal basin (88.2%) and radiation therapy (RT) boost (59.1%), and treatment intensification to involved common iliac LNs by LN dissection (76.4%) and RT boost (63.6%). Conclusions: Our analysis reveals that the vast majority of surveyed U.S. ROs approach pts with involved LPLNs, both regional (internal iliac) and metastatic (i.e. common iliac) with curative intent. They recommend treatment intensification with surgical resection and/or RT boost to involved nodes. Prospective clinical trials need to determine the appropriate management of pts with Stage 3.5 rectal cancer.

Dual-energy CT can detect malignant lymph nodes in rectal cancer

BackgroundThere is a need for an accurate and operator independent method to assess the lymph node status to provide the most optimal personalized treatment for rectal cancer patients.This study evaluates whether Dual Energy Computed Tomography (DECT) could contribute to the preoperative lymph node assessment, and compared it to Magnetic Resonance Imaging (MRI).The objective of this prospective observational feasibility study was to determine the clinical value of the DECT for the detection of metastases in the pelvic lymph nodes of rectal cancer patients and compare the findings to MRI and histopathology. Materials and methodsThe patients were referred to total mesorectal excision (TME) without any neoadjuvant oncological treatment. After surgery the rectum specimen was scanned, and lymph nodes were matched to the pathology report.Fifty-four histology proven rectal cancer patients received a pelvic DECT scan and a standard MRI.The Dual Energy CT quantitative parameters were analyzed: Water and Iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value, for the benign and malignant lymph node differentiation. ResultsDECT scanning showed statistical difference between malignant and benign lymph nodes in the measurements of iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value.Dual energy CT classified 42% of the cases correctly according to N-stage compared to 40% for MRI. ConclusionThis study showed statistical difference in several quantitative parameters between benign and malignant lymph nodes. There were no difference in the accuracy of lymph node staging between DECT and MRI.

Discrimination of metastatic from non-metastatic mesorectal lymph nodes in rectal cancer using quantitative dynamic contrast-enhanced magnetic resonance imaging

Preoperative detection of lymph nodes (LNs) metastasis is always highly challenging for radiologists nowadays. The utility of quantitative dynamic contrast-enhanced magnetic resonance imaging (QDCE-MRI) in identifying LNs metastasis is not well understood. In the present study, 59 patients with histologically proven rectal carcinoma underwent preoperative QDCE-MRI. The short axis diameter ratio, long axis diameter ratio, short-to-long axis diameter ratio and QDEC-MRI parameters (K(trans), Kep, fPV and Ve) values were compared between the non-metastatic (n=44) and metastatic (n=35) LNs groups based on pathological examination. Compared with the non-metastatic group, the metastatic group exhibited significantly higher short axis diameter (7.558±0.668 mm vs. 5.427±0.285 mm), K(trans) (0.483±0.198 min(-1) vs. 0.218±0.116 min(-1)) and Ve (0.399±0.118 vs. 0.203±0.096) values (all P<0.05). The short-to-long axis diameter ratio, long axis diameter ratio, Kep and fPV values did not show significant differences between the two groups. In conclusion, our results showed that for LNs larger than 5 mm in rectal cancer, there are distinctive differences in the K(trans) and Ve values between the metastatic and non-metastatic LNs, suggesting that QDCE-MRI may be potentially helpful in identifying LNs status.

Nodal staging in rectal cancer: why is restaging after chemoradiation more accurate than primary nodal staging?

PurposeThis study aims to explore the influence of chemoradiation treatment (CRT) on rectal cancer nodes and to generate hypotheses why nodal restaging post-CRT is more accurate than at primary staging.MethodsThirty-nine patients with locally advanced rectal cancer underwent MRI pre- and post-CRT. All visible mesorectal nodes were measured on a 3D T1-weighted gradient echo (3D T1W GRE) sequence with 1-mm3 voxels and matched between pre- and post-CRT-MRI and with histology by lesion-by-lesion matching. Change in number and size of nodes was compared between pre- and post-CRT-MRI. ROC curves were constructed to assess diagnostic performance of size.ResultsEight hundred ninety-five nodes were found pre-CRT: 44 % disappeared and 40 % became smaller post-CRT. Disappearing nodes were initially significantly smaller than nodes that remained visible post-CRT: 2.9 mm vs. 3.8 mm. cN+ stage was predicted in 97 % pre-CRT and 36 % of patients had ypN+ post-CRT. ypN+ patients had significantly larger nodes than ypN0 patients both pre- and post-CRT. Optimal size cutoff for post-CRT ypN stage prediction was 2.5 mm (area under the curve (AUC) of 0.78) at MRI.ConclusionsAfter CRT, most lymph nodes become smaller, and many disappear. Size predicts disappearance and node positivity. Together with a low prevalence of ypN+, this can explain the higher accuracy of nodal staging after CRT than in a primary staging setting, possibly of use when considering organ-preserving strategies after CRT.