Assessment for diagnosis of lymph node metastasis in esophageal cancer using endoscopic ultrasound elastography

Significance of Lymph Node Metastasis in the Treatment of Gastric Cancer and Current Challenges in Determining the Extent of Metastasis

The stomach exhibits abundant lymphatic flow, and metastasis to lymph nodes is common. In the case of gastric cancer, there is a regularity to the spread of lymph node metastasis, and it does not easily metastasize outside the regional nodes. Furthermore, when its extent is limited, nodal metastasis of gastric cancer can be cured by appropriate lymph node dissection. Therefore, identifying and determining the extent of lymph node metastasis is important for ensuring accurate diagnosis and appropriate surgical treatment in patients with gastric cancer. However, precise detection of lymph node metastasis remains difficult. Most nodal metastases in gastric cancer are microscopic metastases, which often occur in small-sized lymph nodes, and are thus difficult to diagnose both preoperatively and intraoperatively. Preoperative nodal diagnoses are mainly made using computed tomography, although the specificity of this method is low because it is mainly based on the size of the lymph node. Furthermore, peripheral nodal metastases cannot be palpated intraoperatively, nodal harvesting of resected specimens remains difficult, and the number of lymph nodes detected vary greatly depending on the skill of the technician. Based on these findings, gastrectomy with prophylactic lymph node dissection is considered the standard surgical procedure for gastric cancer. In contrast, several groups have examined the value of sentinel node biopsy for accurately evaluating nodal metastasis in patients with early gastric cancer, reporting high sensitivity and accuracy. Sentinel node biopsy is also important for individualizing and optimizing the extent of uniform prophylactic lymph node dissection and determining whether patients are indicated for function-preserving curative gastrectomy, which is superior in preventing post-gastrectomy symptoms and maintaining dietary habits. Notably, advancements in surgical treatment for early gastric cancer are expected to result in individualized surgical strategies with sentinel node biopsy. Chemotherapy for advanced gastric cancer has also progressed, and conversion gastrectomy can now be performed after downstaging, even in cases previously regarded as inoperable. In this review, we discuss the importance of determining lymph node metastasis in the treatment of gastric cancer, the associated difficulties, and the need to investigate strategies that can improve the diagnosis of lymph node metastasis.

Enhanced EUS imaging (with videos)

BACKGROUND AND AIMS

EUS remains a primary diagnostic tool for the evaluation of pancreaticobiliary disease. Although EUS combined with FNA or biopsy sampling is highly sensitive for the diagnosis of neoplasia within the pancreaticobiliary tract, limitations exist in specific clinical settings such as chronic pancreatitis. Enhanced EUS imaging technologies aim to aid in the detection and diagnosis of lesions that are commonly evaluated with EUS.

METHODS

We reviewed technologies and methods for enhanced imaging during EUS and applications of these methods. Available data regarding efficacy, safety, and financial considerations are summarized.

RESULTS

Enhanced EUS imaging methods include elastography and contrast-enhanced EUS (CE-EUS). Both technologies have been best studied in the setting of pancreatic mass lesions. Robust data indicate that neither technology has adequate specificity to serve as a stand-alone test for pancreatic malignancy. However, there may be a role for improving the targeting of sampling and in the evaluation of peritumoral lymph nodes, inflammatory pancreatic masses, and masses with nondiagnostic FNA or fine-needle biopsy sampling. Further, novel applications of these technologies have been reported in the evaluation of liver fibrosis, pancreatic cysts, and angiogenesis within neoplastic lesions.

CONCLUSIONS

Elastography and CE-EUS may improve the real-time evaluation of intra- and extraluminal lesions as an adjunct to standard B-mode and Doppler imaging. They are not a replacement for EUS-guided tissue sampling but provide adjunctive diagnostic information in specific clinical situations. The optimal clinical use of these technologies continues to be a focus of ongoing research.

Diagnostic performance of diffusion-weighted magnetic resonance imaging in assessing lymph node metastasis of esophageal cancer compared with PET

BACKGROUND

Although diffusion-weighted magnetic resonance imaging (DWI) for detecting lymph node (LN) metastasis is reported to be a successful modality for primary malignant tumors, there are few studies relating to esophageal cancer. This study aimed to clarify the diagnostic performance of DWI for assessing LN metastasis compared with positron emission tomography (PET) in patients with esophageal squamous cell cancer (eSCC).

METHODS

Seventy-six patients with histologically proven eSCC who underwent curative esophagectomy without neoadjuvant treatment were reviewed retrospectively. Harvested LNs were divided into 1229 node stations with 94 metastases. Diagnostic abilities and prognostic significance were compared.

RESULTS

In a station-by-station evaluation, the sensitivity was higher in DWI than PET (67% vs. 32%, P < 0.001). DWI showed more than 80% sensitivity for middle- and large-sized cancer nests and large area of cancer nests. The DWI-N0 group had a better 5-year relapse-free survival rate than the DWI-N+ group (78.5% vs. 34.2%, P < 0.001), as did the PET-N0 group. DWI-N status was an independent prognostic factor (hazard ratio [HR], 2.642; P = 0.048), as was PET-N status (HR 2.481; P = 0.033).

CONCLUSIONS

DWI, which depends on cancer cell volume followed by elevated intranodal density, is a non-invasive modality and showed higher sensitivity than PET. It has clinical impact in predicting postoperative survival for patients with eSCC alongside its diagnostic ability and has significant performance in clinical practice.

Do we need elastography for EUS?

We recently introduced a series of papers “What should be known prior to performing EUS exams.” In Part I, the authors discussed which clinical information and whether other imaging modalities are needed before embarking EUS examinations. In Part II, technical controversies on how EUS is performed were discussed from different points of view. In this article, important practical issues regarding EUS elastography will be raised and controversially discussed from very different points of view.

Compressive Sonoelastography Findings of Esophageal Carcinoma

Objective

The aim of this study was to evaluate the compressive sonoelastography findings of primary esophageal carcinoma.

Materials and Methods

Esophageal specimens of the patients with a tumor staged earlier than T2, with no lymphadenopathy or distant metastasis, who underwent surgery, were evaluated by compressive sonoelastography under ex vivo conditions immediately following surgical excision. The compressive sonoelastography findings of primary esophageal carcinoma were recorded. Compressive sonoelastography measurements were made according to the esophageal muscle because of lack of fat tissue.

Results

The mean elasticity score was 3±1 (range, 1-4), and the mean strain ratio was 1±0.9 (range, 0.3-2.9).

Conclusion

Primary esophageal carcinoma is stiff based on the elasticity score, and it demonstrated a mean strain ratio similar to the esophageal muscle.

Reliability of clinical nodal status regarding response to neoadjuvant chemoradiotherapy compared with surgery alone and prognosis in esophageal cancer patients

Background: Clinical nodal (cN) staging is a key element in treatment decisions in patients with esophageal cancer (EC). The reliability of cN status regarding the effect on response and survival after neoadjuvant chemoradiotherapy (nCRT) with esophagectomy was evaluated in determining the up- and downstaged pathological nodal (pN) status after surgery alone. Material and methods: From a prospective database, we included all 395 EC patients who had surgery with curative intent with or without nCRT between 2000 and 2015. All patients were staged by a standard pretreatment protocol: 16-64 mdCT, 18 F-FDG-PET or 18 F-FDG-PET/CT and EUS ± FNA. After propensity score matching on baseline clinical tumor and nodal (cT/N) stage and histopathology, a surgery-alone and nCRT group (each N = 135) were formed. Clinical and pathological N stage was scored as equal (cN = pN), downstaged (cN > pN) or upstaged (cN < pN). Prognostic impact on disease free survival (DFS) was assessed with multivariable Cox regression analysis (factors with p value <.1 on univariable analysis). Results: The surgery-alone and nCRT group did not differ in cT/N status. Pathologic examination revealed equal staging (32 vs. 27%), nodal up (43 vs. 16%) and downstaging (25 vs. 56%), respectively (p < .001). Nodal up-staging was common in cT3-4a tumors and adenocarcinomas in the surgery-alone group, while nodal downstaging was found in half of cT1-2 and cT3-4 regardless of tumortype after nCRT. Prognostic factors for DFS were pN (p = .002) and lymph-angioinvasion (p = .016) in surgery-alone, and upper abdominal cN metastases (p = .012) and lymph node ratio (p = .034) in the nCRT group. Conclusions: Despite modern staging methods, correct cN staging remains difficult in EC. Nodal overstaging (cN > pN) occurred more often than understaging impeding an adequate assessment of pathologic complete response and prognosis after nCRT.

Diagnostic value of endoscopic ultrasound elastography for benign and malignant digestive system tumors

Objective:

To investigate the effect of endoscopic ultrasound real-time tissue elastography in differential diagnosis of benign and malignant digestive system tumors.

Methods:

Forty-two patients with solid tumors of digestive system who were admitted to our hospital between October 2017 and October 2018 were selected. All patients were diagnosed by endoscopic ultrasound real-time tissue elastography. Elastography score was used. The strain ratios (SR) of the lesion and the surrounding control tissues were measured and compared.

Results:

Lesions with elastography score no more than two points were evaluated as benign, while lesions with elastography score no less than three points were evaluated as malignant. The difference of the elastography score between the benign lesion group and malignant lesion group was statistically significant (P<0.05). The sensitivity, specificity and accuracy of endoscopic ultrasound elastography in the diagnosis of malignant tumors of digestive system were 91.4%, 88.9% and 87.5%, respectively. The SR of the benign lesions ranged from 0.01 to 7.34, with a median SR of 7.33; the SR of the malignant lesions ranged from 1.01 to 47.66, with a median SR of 20.07. The SR of the benign lesions was significantly lower than that of the malignant lesions (P<0.05).

Conclusion:

Elastography of benign and malignant tissues of digestive tract tumors has different image characteristics. Endoscopic ultrasound real-time tissue elastography is effective in differential diagnosis of digestive tract tumors as it can effectively determine whether a tumor is benign or malignant and improve diagnostic accuracy.

Predictive Factors for Inaccurate Diagnosis of Swollen Lymph Nodes in Endoscopic Ultrasound-Guided Fine Needle Aspiration

Background/Aims

This study aimed to identify the predictive factors for inaccurate endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) diagnosis of swollen lymph nodes without rapid on-site cytopathological evaluation.

Methods

Eighty-three consecutive patients who underwent EUS-FNA for abdominal or mediastinal lymph nodes from January 2008 to June 2017 were included from a prospectively maintained EUS-FNA database and retrospectively reviewed. The sensitivity, specificity, and accuracy of EUS-FNA for the detection of neoplastic diseases were calculated. Candidate factors for inaccurate diagnosis (lymph node size and location, needle type, puncture route, number of passes, and causative disease) were evaluated by comparison between accurately diagnosed cases and others.

Results

The final diagnosis of the punctured lymph node was classified as neoplastic (65 cases: a metastatic lymph node, malignant lymphoma, or Crow-Fukase syndrome) or non-neoplastic (18 cases: a reactive node or amyloidosis). The sensitivity, specificity, and accuracy were 83%, 94%, and 86%, respectively. On multivariate analyses, small size of the lymph node was the sole predictive factor for inaccurate EUS-FNA diagnosis with a significant difference (odds ratios, 19.8; 95% confidence intervals, 3.15–124; p=0.0015).

Conclusions

The lymph node size of <16 mm was the only independent factor associated with inaccurate EUS-FNA diagnosis of swollen lymph nodes.

EUS elastography: How to do it?

Strain elastography as used in EUS (EUS-real-time tissue elastography [RTE]) is a qualitative technique and provides information on the relative stiffness between one tissue and another. This article reviews the principles, technique, and interpretation of EUS-RTE in various organs. It includes information on how to optimize the technique as well as a discussion on pitfalls and artifacts. We also refer to the article describing RTE using conventional ultrasound transducers.

Endoscopic ultrasound-guided fine-needle aspiration and cytology for differentiating benign from malignant lymph nodes

BACKGROUND AND STUDY AIMS

Intra-abdominal and mediastinal lymphadenopathy are often difficult to diagnose, particularly in the absence of a primary lesion. Endosonography (EUS)-guided fine-needle aspiration and cytology (FNAC) has provided an easy and safe access to these lymph nodes, sparing the use of invasive and costly interventions. The main aim of this study is to assess the specificity, sensitivity, and predictive value of EUS-guided FNAC in the diagnosis of benign and malignant lymph nodes. In addition, the study aims to determine significant EUS features that could help in predicting lymph node malignancy.

PATIENTS AND METHODS

This prospective study included 142 patients with intra-abdominal or intrathoracic lymphadenopathy who were referred for EUS-guided FNAC because of inaccessibility by other imaging modalities. Ninety (63.3%) patients were found to have malignant lymph nodes, and 52 (36.6%) had lymphadenopathy of benign nature.

RESULTS

EUS-guided FNAC had a sensitivity and specificity of 92% and 100% respectively. It had positive and negative predictive values of 100% and 88% for malignancy, respectively. By logistic regression analysis, EUS features and shortest diameter were found to be potential predictors of malignancy with p-value of <0.0001.

CONCLUSION

EUS-guided FNAC is a powerful modality in the diagnosis of benign and malignant lymph nodes. Additional complementary EUS features could be added to this technique for definitive diagnosis.

Is endoscopic ultrasound examination necessary in the management of esophageal cancer?

Despite substantial efforts at early diagnosis, accurate staging and advanced treatments, esophageal cancer (EC) continues to be an ominous disease worldwide. Risk factors for esophageal carcinomas include obesity, gastroesophageal reflux disease, hard-alcohol use and tobacco smoking. Five-year survival rates have improved from 5% to 20% since the 1970s, the result of advances in diagnostic staging and treatment. As the most sensitive test for locoregional staging of EC, endoscopic ultrasound (EUS) influences the development of an optimal oncologic treatment plan for a significant minority of patients with early cancers, which appropriately balances the risks and benefits of surgery, chemotherapy and radiation. EUS is costly, and may not be available at all centers. Thus, the yield of EUS needs to be thoughtfully considered for each patient. Localized intramucosal cancers occasionally require endoscopic resection (ER) for histologic staging or treatment; EUS evaluation may detect suspicious lymph nodes prior to exposing the patient to the risks of ER. Although positron emission tomography (PET) has been increasingly utilized in staging EC, it may be unnecessary for clinical staging of early, localized EC and carries the risk of false-positive metastasis (over staging). In EC patients with evidence of advanced disease, EUS or PET may be used to define the radiotherapy field. Multimodality staging with EUS, cross-sectional imaging and histopathologic analysis of ER, remains the standard-of-care in the evaluation of early esophageal cancers. Herein, published data regarding use of EUS for intramucosal, local, regional and metastatic esophageal cancers are reviewed. An algorithm to illustrate the current use of EUS at The University of Texas MD Anderson Cancer Center is presented.