[Endoscopic ultrasound in routine clinical practice for staging adenocarcinomas of the stomach and distal esophagus]

Diagnostic accuracy of endoscopic ultrasonography (EUS) for the preoperative locoregional staging of primary gastric cancer

BACKGROUND

Endoscopic ultrasound (EUS) is proposed as an accurate diagnostic device for the locoregional staging of gastric cancer, which is crucial to developing a correct therapeutic strategy and ultimately to providing patients with the best chance of cure. However, despite a number of studies addressing this issue, there is no consensus on the role of EUS in routine clinical practice.

OBJECTIVES

To provide both a comprehensive overview and a quantitative analysis of the published data regarding the ability of EUS to preoperatively define the locoregional disease spread (i.e., primary tumor depth (T-stage) and regional lymph node status (N-stage)) in people with primary gastric carcinoma.

SEARCH METHODS

We performed a systematic search to identify articles that examined the diagnostic accuracy of EUS (the index test) in the evaluation of primary gastric cancer depth of invasion (T-stage, according to the AJCC/UICC TNM staging system categories T1, T2, T3 and T4) and regional lymph node status (N-stage, disease-free (N0) versus metastatic (N+)) using histopathology as the reference standard. To this end, we searched the following databases: the Cochrane Library (the Cochrane Central Register of Controlled Trials (CENTRAL)), MEDLINE, EMBASE, NIHR Prospero Register, MEDION, Aggressive Research Intelligence Facility (ARIF), ClinicalTrials.gov, Current Controlled Trials MetaRegister, and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), from 1988 to January 2015.

SELECTION CRITERIA

We included studies that met the following main inclusion criteria: 1) a minimum sample size of 10 patients with histologically-proven primary carcinoma of the stomach (target condition); 2) comparison of EUS (index test) with pathology evaluation (reference standard) in terms of primary tumor (T-stage) and regional lymph nodes (N-stage). We excluded reports with possible overlap with the selected studies.

DATA COLLECTION AND ANALYSIS

For each study, two review authors extracted a standard set of data, using a dedicated data extraction form. We assessed data quality using a standard procedure according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria. We performed diagnostic accuracy meta-analysis using the hierarchical bivariate method.

MAIN RESULTS

We identified 66 articles (published between 1988 and 2012) that were eligible according to the inclusion criteria. We collected the data on 7747 patients with gastric cancer who were staged with EUS. Overall the quality of the included studies was good: in particular, only five studies presented a high risk of index test interpretation bias and two studies presented a high risk of selection bias.For primary tumor (T) stage, results were stratified according to the depth of invasion of the gastric wall. The meta-analysis of 50 studies (n = 4397) showed that the summary sensitivity and specificity of EUS in discriminating T1 to T2 (superficial) versus T3 to T4 (advanced) gastric carcinomas were 0.86 (95% confidence interval (CI) 0.81 to 0.90) and 0.90 (95% CI 0.87 to 0.93) respectively. For the diagnostic capacity of EUS to distinguish T1 (early gastric cancer, EGC) versus T2 (muscle-infiltrating) tumors, the meta-analysis of 46 studies (n = 2742) showed that the summary sensitivity and specificity were 0.85 (95% CI 0.78 to 0.91) and 0.90 (95% CI 0.85 to 0.93) respectively. When we addressed the capacity of EUS to distinguish between T1a (mucosal) versus T1b (submucosal) cancers the meta-analysis of 20 studies (n = 3321) showed that the summary sensitivity and specificity were 0.87 (95% CI 0.81 to 0.92) and 0.75 (95% CI 0.62 to 0.84) respectively. Finally, for the metastatic involvement of lymph nodes (N-stage), the meta-analysis of 44 studies (n = 3573) showed that the summary sensitivity and specificity were 0.83 (95% CI 0.79 to 0.87) and 0.67 (95% CI 0.61 to 0.72), respectively.Overall, as demonstrated also by the Bayesian nomograms, which enable readers to calculate post-test probabilities for any target condition prevalence, the EUS accuracy can be considered clinically useful to guide physicians in the locoregional staging of people with gastric cancer. However, it should be noted that between-study heterogeneity was not negligible: unfortunately, we could not identify any consistent source of the observed heterogeneity. Therefore, all accuracy measures reported in the present work and summarizing the available evidence should be interpreted cautiously. Moreover, we must emphasize that the analysis of positive and negative likelihood values revealed that EUS diagnostic performance cannot be considered optimal either for disease confirmation or for exclusion, especially for the ability of EUS to distinguish T1a (mucosal) versus T1b (submucosal) cancers and positive versus negative lymph node status.

AUTHORS' CONCLUSIONS

By analyzing the data from the largest series ever considered, we found that the diagnostic accuracy of EUS might be considered clinically useful to guide physicians in the locoregional staging of people with gastric carcinoma. However, the heterogeneity of the results warrants special caution, as well as further investigation for the identification of factors influencing the outcome of this diagnostic tool. Moreover, physicians should be warned that EUS performance is lower in diagnosing superficial tumors (T1a versus T1b) and lymph node status (positive versus negative). Overall, we observed large heterogeneity and its source needs to be understood before any definitive conclusion can be drawn about the use of EUS can be proposed in routine clinical settings.

Electrical stimulation to increase lower esophageal sphincter pressure after POEM

INTRODUCTION

Postoperative reflux remains to be a challenge for patients with achalasia undergoing Heller myotomy. Similarly, per-oral endoscopic myotomy (POEM) is gaining rapid acceptance but the impossibility of adding a fundoplication is questioned as the main pitfall to control reflux. Electrical stimulation of the lower esophageal sphincter (LES) has emerged as a new alternative for the treatment of reflux disease. The objective of this study was to evaluate the potential benefits of combining electrical stimulation with endoscopic esophageal myotomy to prevent post procedural reflux.

METHODS

Five pigs were subjected to POEM. After myotomy was completed, two electrical leads were implanted at the LES level and electrical stimulation was applied with the Endostim system with a regimen of 215 μs (5 mA amplitude), at 20 Hz for 25 min. LES pressures were recorded with manometry at pre and post-myotomy and after LES stimulation.

RESULTS

Myotomy was completed successfully in all cases. Mean pre-myotomy LES pressure was 35.99 ± 8.08 mmHg. After myotomy, the LES pressure significantly dropped to 10.60 ± 3.24 mmHg (p = 0.03). Subsequent to LES-EST, LES pressure significantly increased to 21.74 ± 4.65 mmHg (p = 0.01).

CONCLUSIONS

The findings of this study show that LES-EST in healthy animals increases LES pressure after POEM procedure, and could be useful tool to minimize gastroesophageal reflux.

Staging and outcome depending on surgical treatment in adenocarcinomas of the oesophagogastric junction

BACKGROUND

Owing to controversial staging and classification of adenocarcinoma of the oesophago-gastric junction (AOG) before surgery, the choice of appropriate surgical approach remains problematic. In a retrospective study, preoperative staging of AOG and the impact of preoperative misclassification on outcome were analysed.

METHODS

Data from patients with AOG were analysed from a prospectively collected database with regard to surgical treatment, preoperative and postoperative staging, and outcome.

RESULTS

One-hundred and thirty patients with Siewert types I and II AOG who did not have neoadjuvant treatment were included in the study: 41 patients with an AOG type I who underwent oesophagectomy, 51 patients with an AOG staged before surgery as type I who underwent oesophagectomy but in whom the final histology showed a type II tumour, and 38 patients whose tumours were staged as AOG type II before and after operation who underwent gastrectomy. Among patients who had an oesophagectomy, lymph node metastases (P = 0.022), tumour relapse (P = 0.009) and recurrent distant metastases (P = 0.028) were significantly more frequent in patients with AOG type II; those with AOG type II had shorter overall survival than those with type I tumours (P = 0.024). Among those with AOG type II, recurrence-free survival was significantly shorter after oesophagectomy compared with extended gastrectomy (P = 0.019). Thoracoabdominal oesophagectomy had a favourable influence on outcome compared with the transhiatal approach.

CONCLUSION

Accurate preoperative staging of AOG and appropriate surgical therapy are crucial for outcome. AOG type II is a more aggressive tumour with higher recurrence rates than AOG type I. These patients therefore benefit from more radical surgical treatment.

Metabolic response evaluation by PET during neoadjuvant treatment for adenocarcinoma of the esophagus and esophagogastric junction

Following several randomized trials, neoadjuvant therapy in adenocarcinoma of esophagus and the esophagogastric junction can be seen as an international standard. However, in a large proportion of patients the objective response achieved is unsatisfactory. These patients do not benefit from neoadjuvant therapy, but do suffer from toxic side effects; sometimes progressive and appropriate surgical therapy is delayed. For this reason, a diagnostic test that can accurately assess tumor response to neoadjuvant therapy might be of crucial importance. Response evaluation using CT scan, endoluminal ultrasound, or rebiopsy is not reliable. In recent times, response evaluation using 18FGD PET after and during neoadjuvant treatment is in the focus of clinical and scientific interest. Most studies have evaluated the diagnostic modalities for response to neoadjuvant treatment after completion of the treatment. Following the published data so far, FDG-PET seems to be less accurate after and during chemoradiation than after chemotherapy alone. The data of early response evaluation (14 days after the onset of chemotherapy) are very much encouraging; however, they have to be evaluated in an international randomized trial. Standardization of PET technology as well as defining the thresholds used for the estimation of early response is mandatory. So far, FDG-PET does not change treatment in esophageal and gastric cancer.

Endoluminal MR imaging of porcine gastric structure in vivo

BACKGROUND AND AIMS

Recently, several new endoscopic instruments have been developed. However, even with the full use of current modalities, the safety of endoscopic surgery is not guaranteed. Information regarding factors such as fibrosis and the blood vessels under the mucosa is very important for avoiding procedure-related complications. The aim of this study was to define the detailed anatomy of the gastric wall structure in vivo using original endoluminal radiofrequency coils for safer endoscopic therapy.

METHODS

Swine were used as the subjects and controlled with general anesthesia. Anatomical images were obtained with T1-weighted fast spin echo (T1FSE) and T2-weighted fast spin echo (T2FSE). Dynamic magnetic resonance (MR) angiography was also obtained with three-dimensional T1-weighted fast spoiled gradient recalled acquisition in the steady state (3D-DMRA) following the injection of hyaluronic acid sodium into the submucosal layer.

RESULTS

Porcine gastric wall structure was visualized, and four layers were discriminated in the T1FSE and T2FSE images. The vascular structure was clearly recognized in the submucosa on 3D-DMRA.

CONCLUSION

Endoluminal MR imaging was able to visualize the porcine stomach with similar quality to endoscopic ultrasonography imaging. Additionally, it was possible to visualize the vascular structures in the submucosal layer. This is the first report to show that blood vessels under the gastric mucosa can be depicted in vivo.

MRI of gastric carcinoma: Results of T and N-staging in an in vitro study

AIM: To determine the accuracy of 1.5-T magnetic resonance imaging (MRI) in the evaluation of gastric wall invasion and perigastric lymph node metastasis in gastric adenocarcinoma.

METHODS: Twenty resected gastric specimens containing 20 tumors were studied with a 1.5-T MR system using a commercial head surface coil. MR scanning was performed with a T1 weighted image (TR/TE = 500/20), and a T2 weighted image (TR/TE = 2500/90). MR findings were compared with pathologic findings.

RESULTS: A T1-weighted image demonstrated three layers in the normal gastric wall. All of the gastric tumors were well demonstrated by lesions and location. In a MRI findings of gastric wall invasion, there was 1 case of T1, 7 of T2, 11 of T3. Pathologic results of resected specimens included 3 cases of pT1, 4 of pT2, and 12 of pT3. The accuracy of T staging with MRI was 74% (14 of 19). MRI findings of lymph node metastasis included 6 cases of N0, 13 cases of N1. The accuracy of the N staging with MRI was 47% (9 of 19).

CONCLUSION: MRI has a high diagnostic accuracy in the evaluation of the T staging of gastric cancer in vitro and thus potentially enables preoperative histopathologic staging.

Endoscopic ultrasound with conventional probe and miniprobe in preoperative staging of esophageal cancer

BACKGROUND

Using an endoscopic ultrasound (EUS) miniprobe, even highly stenotic esophageal cancers precluding the passage of a conventional probe can be examined without prior dilatation.

OBJECTIVE

To assess: (1) staging accuracy of conventional EUS probe and miniprobe, (2) variables influencing staging accuracy, (3) endoscopic features predicting tumor stage.

METHODS

Ninety-seven consecutive patients with esophageal cancer undergoing complete surgical resection were included. Preoperative EUS was performed using a conventional probe in nonstenotic tumors and a miniprobe in stenotic tumors. Accuracy of EUS for T and N stages was compared to pathohistological staging.

RESULTS

Overall EUS staging accuracy was 73.2% for T stage and 74.2% for N stage. It was similar for the miniprobe used in stenotic tumors vs the conventional probe used in nonstenotic tumors. Based on EUS, 84.5% of the patients would have been assigned to the appropriate therapy protocol (primary surgery vs neoadjuvant therapy). Endoscopic tumor features had no influence on staging accuracy. Tumor length >5 cm predicted advanced T and nodal positive stages.

CONCLUSIONS

The miniprobe allows adequate EUS staging of stenotic esophageal tumors precluding the passage of a conventional probe. Therefore, dilatation therapy of stenotic cancers to conduct conventional EUS should be avoided.

Does endoscopic ultrasound staging already allow individual treatment regimens in gastric cancer

AIM

The aim of our study was to evaluate the accuracy of preoperative TNM staging with endoscopic ultrasound (EUS) in gastric cancer patients in comparison with the pathohistological stage of the resected specimen, and to determine the possible implications of EUS for individualized treatment of gastric cancer patients at our institution.

PATIENTS AND METHODS

The study included 82 patients operated for resectable gastric cancer between January 1(st) 2001 and July 1(st) 2003 at the Maribor Teaching Hospital Department of Abdominal and General Surgery. The EUS stage was assessed preoperatively at the Endoscopical Unit, and the pathohistological stage in the resected specimen was determined postoperatively at the Department of Pathologic Morphology according to recommended standards.

RESULTS

Comparison of EUS and pathohistological assessments revealed accuracy of EUS staging for locoregional tumor infiltration (category T) in 68% of patients. The accuracy of EUS staging was 68% for T1, 69% for T2, 69% for T3 and 60% for T4. Lymph nodes (category N) were correctly staged with EUS in 57% of cases. The EUS stage was correct for lymph nodes with no metastases (N-) in 40% of cases, and for lymph nodes with metastases (N+) in 90%. There was no significant difference in accuracy of EUS staging with regard to tumor site (P = 0.768) or tumor size (P = 0.766).

CONCLUSIONS

According to our results the accuracy of EUS staging matched pathohistological staging with regard to tumor infiltration and lymph node stage in 68% and 57% of cases respectively. Underestimation of the final T2 and T3 stages as T1 stage by EUS presents a problem regarding the consistency of EUS examination at our institution, particularly with respect to individual treatment for early gastric cancer. The present uncertainty in EUS stage reliability makes it necessary to have a strategy of radical resection with D2 lymphadenectomy in patients within EUS stages T1-T3, with additional CT examinations in more advanced EUS stages in order to visualize the circumstances of tumor growth. Nevertheless, EUS provides an opportunity for the surgeon to gain more insight into the loco-regional circumstances of the gastric tumor process. For development of individual modes of treatment based on EUS staging, a more reliable assessment of EUS stage is mandatory.

New coil concept for endoluminal MR imaging: initial results in staging of gastric carcinoma in correlation with histopathology

Our aim was to conduct a prospective study to evaluate staging accuracy of a new coil concept for endoluminal magnetic resonance imaging (MRI) on ex vivo gastric carcinomas. Twenty-eight consecutive patients referred to surgery with a clinically proven primary gastric malignancy were included. Surgical specimens were examined with a foldable and self-expanding loop coil (8-cm diameter) at 1.5 Tesla immediately after total gastrectomy. T1- and T2-weighted and opposed-phase sequences (axial, frontal sections; 3- to 4-mm slice thickness) were acquired. Investigators blinded to any patient information analyzed signal intensity of normal gastric wall, gastric tumor, and lymph nodes. Findings were compared with histopathological staging. On surgical specimens, 2-5 gastric wall layers could be visualized. All gastric tumors (26 carcinomas, two lymphomas) were identified on endoluminal MR data (100%). Overall accuracy for T staging was 75% (18/24); sensitivity to detect serosal involvement was 80% and specificity 89%. N staging correlated in 58% (14/24) with histopathology (N+ versus N-). The endoluminal coil concept is feasible and applicable for an ex vivo setting. Endoluminal MR data provided sufficient detail for gastric wall layer differentiation, and therefore, identification of T stages in gastric carcinoma is possible. Further investigations in in vivo settings should explore the potential of our coil concept for endoluminal MR imaging.

Diagnostics of rectal cancer: endorectal ultrasound

In rectal cancer, accurate preoperative staging is essential to adequately select patients for different therapeutic regimes. Endosonography has been proven to be an accurate staging modality in multiple prospective studies. A recent large retrospective study, however, has cast doubt on the actual accuracy of endorectal ultrasound for staging rectal cancer in everyday clinical routines. The results of endosonographic staging of rectal tumours over a period of 10 years at the Department of Surgery of the University of Heidelberg are presented. In a first time period, 424 patients with rectal cancer were staged by endosonography and the data recorded prospectively. The examinations were exclusively done by four surgeons with high experience and scientific interest in endosonography. The second time period comprises 332 patients with rectal tumours (including adenomas) having undergone endosonography by six different examiners after introduction of this staging method into the clinical routine. The data here were analysed retrospectively. Accuracy, sensitivity, specificity, and positive and negative predictive values were calculated for the T and N classifications for both series. In the second series, eight factors which have been postulated to influence staging accuracy in the literature were included in a regression analysis in order to identify relevant factors for staging inaccuracies. Accuracy for staging of the T classification was 81% in the first series versus 71.7% in the second series. In the regression analysis of the second series, status post-chemoradiation proved to be the most significant factor for staging inaccuracy (p < 0.0002). When excluding all patients having undergone chemoradiation, the accuracy for staging of the T classification rose to 76%. A major problem of endosonography in this second series was overstaging; the T category was overestimated in 76 cases (22.9% of patients). The main error here was overstaging of adenomas as cancerous lesions (45.5% of all adenomas) and T2-cancers as more advanced cancers (42.2% of all T2-cancers). When excluding the adenomas from this analysis, the accuracy increased to 73.5%. Accuracy for staging of the N classification was 76% in the first series versus 71% in the second series. Status post-chemoradiation again was a relevant factor (p < 0.0003); when excluding these patients the accuracy increased to 73%. The accuracy of endosonography for rectal tumours decreases after introduction of the method into the everyday clinical routine. Nonetheless, apart from magnetic resonance imaging with an endorectal coil, rectal endosonography is still the most accurate staging modality for rectal tumours and allows adequate selection of patients for different therapeutic regimes. As the major problem of rectal endosonography is overstaging, more patients are likely to undergo overtreatment rather than undertreatment. Endosonography is inaccurate in staging patients having undergone chemoradiation.

Evaluation of Siewert classification in gastro-esophageal junction adenocarcinoma: What is the role of endoscopic ultrasonography?

BACKGROUND

Preoperative assessment of gastro-esophageal junction (GEJ) adenocarcinoma stage and its location according to Siewert are essential for planning the therapeutic approach. The present study was aimed at analyzing the utility of endoscopic ultrasonography (EUS) in evaluating GEJ adenocarcinoma stage and whether this modality added to EGD improves assessment of Siewert type.

METHODS

The results of 51 patients studied by EGD plus EUS (EGD/EUS group) were compared with the results of 54 patients studied by EGD only (EGD group).

RESULTS

A differentiation of pT1 tumors was attempted by measurement of the tumor length using 4 cm as a criterion. This goal was not achieved because of a high rate of advanced tumors less than 4 cm (sensitivity and specificity were 81.3% and 34.2%, respectively). Conversely EUS ability in pT1 assessment was very reliable (92%). The accuracy in defining the Siewert type was 72.5% and 64.8% for EGD/EUS and EGD groups, respectively (P = 0.394). Some difficulties in distinguishing between type II and III tumors were observed in both groups with an extremely low specificity (44%) in classifying type II tumors by EGD group.

CONCLUSIONS

EUS seems to be essential in differentiating pT1 from advanced tumors. It shows an accuracy in defining the Siewert type of 72.5%, with some difficulties in distinguishing from type II and III tumors.