Impact of miniprobe ultrasonography on planning of minimally invasive surgery for gastric and colonic tumors

Controversies in EUS: Do we need miniprobes?

This is the fifth in a series of papers entitled "Controversies in EUS." In the current paper, we deal with high-resolution catheter probes, otherwise known as EUS miniprobes (EUS-MPs). The application of miniprobes for early carcinomas in the entire intestinal tract, for subepithelial lesions, and for findings in the bile duct and pancreatic duct as well as endobronchial use is critically discussed. Submucous lesions, especially in the colon, but also early carcinomas in special cases are considered the most important indications. The argument is illustrated by numerous examples.

Gastrointestinal diagnosis using non-white light imaging capsule endoscopy

Capsule endoscopy (CE) has proved to be a powerful tool in the diagnosis and management of small bowel disorders since its introduction in 2001. However, white light imaging (WLI) is the principal technology used in clinical CE at present, and therefore, CE is limited to mucosal inspection, with diagnosis remaining reliant on visible manifestations of disease. The introduction of WLI CE has motivated a wide range of research to improve its diagnostic capabilities through integration with other sensing modalities. These developments have the potential to overcome the limitations of WLI through enhanced detection of subtle mucosal microlesions and submucosal and/or transmural pathology, providing novel diagnostic avenues. Other research aims to utilize a range of sensors to measure physiological parameters or to discover new biomarkers to improve the sensitivity, specificity and thus the clinical utility of CE. This multidisciplinary Review summarizes research into non-WLI CE devices by organizing them into a taxonomic structure on the basis of their sensing modality. The potential of these capsules to realize clinically useful virtual biopsy and computer-aided diagnosis (CADx) is also reported.

Miniprobe Endoscopic Sonography for Gastrointestinal Tract Assessment: A Case Series of 1451 Procedures

Conventional endoscopic sonography has allowed precise diagnostics without disturbances, and miniprobes can be easily introduced through the biopsy channel of the endoscope. Miniprobe endoscopic sonography has many benefits compared with conventional endoscopic sonography. Although there are well-known indications for miniprobe endoscopic sonography in endoscopic digestive tract assessment, there is still a need for this method to be widely spread among physicians and commonly used by most endoscopists. The aim of this series was to describe a multicenter retrospective experience with 1451 procedures using miniprobes, presenting examples and the applicability and usefulness of this technology in the daily activities of an endoscopy department.

Colon carcinoma staging by endoscopic ultrasonography miniprobes

Background and Objectives:

Due to the increasing use of endoscopic techniques for colon cancer resection, pretreatment locoregional staging may gain critical interest. The use of endoscopic ultrasonography (EUS) miniprobes in this context has been seldom reported. Our aim was to determine the accuracy of EUS miniprobes for colon cancer staging.

Materials and Methods:

Forty patients with colon cancer (2 in the cecum, 9 in the ascending colon, 5 in the transverse colon, 5 in the descending colon, and 19 in the sigmoid colon) were submitted to staging using 12 MHz EUS miniprobes. EUS and the anatomopathological results were compared with regard to the T and N stages. It was assessed if the location, longitudinal extension, or circumferential extension of the tumor had any influence on the accuracy in EUS staging.

Results:

Tumor staging was feasible in 39 (98%) patients except in one case with a stenosing tumor (out of 6). Globally, T stage was accurately determined in 88% of the cases. In the assessment of the presence or absence of lymph node metastasis, miniprobes presented an accuracy of 82% with a sensitivity of 67%. These results were neither affected by the location nor by the longitudinal or circumferential extension of the tumor.

Conclusions:

EUS miniprobes may play an important role in assessing T and N stages in colon cancer and may represent an incentive to the research of new therapeutic areas for this disease.

Therapeutic Decision-Making Using Endoscopic Ultrasonography in Endoscopic Treatment of Early Gastric Cancer

Background/Aims

We evaluated the effectiveness of an endoscopic ultrasonography (EUS)-based treatment plan compared to an endoscopy-based treatment plan in selecting candidates with early gastric cancer (EGC) for endoscopic submucosal dissection based on the prediction of invasion depth.

Methods

We reviewed 393 EGCs with differentiated histology from 380 patients who underwent EUS from July 2007 to April 2010. The effectiveness of the EUS-based and endoscopy-based plans was evaluated using a simplified hypothetical treatment algorithm.

Results

The numbers of endoscopically determined mucosal, indeterminate, and submucosal cancers were 253 (64.4%), 56 (14.2%), and 84 (21.4%), respectively. Overall, the appropriate treatment selection rates were 75.3% (296/393) in the endoscopy-based plan and 71.5% (281/393) in the EUS-based plan (p=0.184). For endoscopic mucosal cancers, the appropriate treatment selection rates in the endoscopy-based plan were 88.1% (223/253), while the use of an EUS-based plan significantly decreased this rate to 81.4% (206/253) (p=0.036). For endoscopic submucosal cancers, the appropriate selection rates did not differ between the endoscopy-based plan (46.4%, 39/84) and the EUS-based plan (53.6%, 45/84) (p=0.070).

Conclusions

EUS did not increase the likelihood of selecting the appropriate treatment in differentiated-type EGC. Therefore, EUS may not be necessary before treating differentiated-type EGC, especially in endoscopically presumed mucosal cancers.

Management of colorectal T1 carcinoma treated by endoscopic resection

As a result of recent advances in endoscopic therapeutic technology, the number of endoscopic resections carried out in the treatment of early colorectal carcinomas with little risk of lymph node metastasis has increased. There are no reports of lymph node metastasis in intramucosal (Tis) carcinomas, whereas lymph node metastasis occurs in 6.8-17.8% of submucosal (T1) carcinomas. Three clinical guidelines have been published in Japan and the management strategy for early colorectal tumors has been demonstrated. According to the 2014 Japanese Society for Cancer of the Colon and Rectum (JSCCR) Guidelines for the Treatment of Colorectal Cancer, additional surgery should be done in cases of endoscopically resected T1 carcinoma with a histologically diagnosed positive vertical margin. Additional surgery may also be considered when one of the following histological findings is detected: (i) SM invasion depth ≥1000 µm; (ii) histological type por., sig., or muc.; (iii) grade 2-3 tumor budding; and (iv) positive vascular permeation. A resected lesion that is histologically diagnosed as a T1 carcinoma without any of the above-mentioned findings can be followed up without additional surgery. As for the prognosis of endoscopically resected T1 carcinomas, the relapse ratio of approximately 3.4% (44/1312) is relatively low. However, relapse is associated with a poor prognosis, with 72 cancer-related deaths reported out of 134 relapsed cases (54%). A more detailed stratification of the lymph node metastasis risk after endoscopic resection for T1 carcinomas and the prognosis of relapsed cases will be elucidated through prospective studies. Thereafter, the appropriate indications and safe and secure endoscopic resection for T1 carcinomas will be established.

Diagnostic performance of EUS for evaluating the invasion depth of early colorectal cancers

BACKGROUND

EUS is one technique used to estimate the invasion depth of early colorectal cancer (CRC), but its diagnostic accuracy remains a matter of debate.

OBJECTIVE

To assess the accuracy of EUS for estimating the invasion depth of early CRC.

DESIGN

Retrospective analysis.

SETTING

Tertiary-care academic medical center.

PATIENTS

The invasion depth of early CRC was estimated by EUS from 1989 through 2012.

INTERVENTIONS EUS MAIN OUTCOME MEASUREMENTS

Accuracy of EUS diagnosis, risk factors for misdiagnosis, and characteristics of lesions that were difficult to image.

RESULTS

We estimated the invasion depth of 714 cases of early CRC on EUS. Of the lesions able to be visualized on EUS, the overall diagnostic accuracy of EUS for differentiating between lesions that could be resected endoscopically (Tis and T1a cancers), and those that required colectomy (T1b cancers) was 89%. Submucosal cancer and a macroscopic classification of superficial type were independent risk factors for misdiagnosis. Ninety lesions (13%) were difficult to image. Risk factors for difficulty in imaging were protruding-type morphology and tumor location in the sigmoid colon or from the descending colon to the cecum.

LIMITATIONS

Single center, retrospective. Experienced endoscopists performed EUS.

CONCLUSIONS

Although some lesions that were protruding or located in the proximal colon were difficult to visualize, EUS is considered a useful technique for the diagnosis of invasion depth and the selection of treatment in patients with early CRC.

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.

Is endoscopic ultrasonography still the modality of choice in preoperative staging of gastric cancer?

The treatment option for gastric cancer is usually based on preoperative staging by imaging modalities. Endoscopic ultrasonography (EUS) and computed tomography (CT) have been used as the diagnostic modality of choice in preoperative staging of gastric cancer. Magnetic resonance imaging (MRI) has been employed in several studies, and (¹⁸F) 2-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has emerged as a new promising imaging modality. The purpose of this article is to provide summarized information on preoperative staging using EUS, multi-detector row CT (MDCT), MRI and PET for gastric cancer. In T staging, both EUS and MDCT show high accuracy. MRI seemed to have better performance, but the number of MRI studies is limited. FDG-PET is not able to properly evaluate the depth of invasion. In N staging, the diagnostic accuracy of EUS, MDCT and MRI is not sufficient. In preoperative M staging, MDCT and FDG-PET showed similar diagnostic accuracies. FDG-PET/CT fusion could be expected to show better performance in the future. Physicians should keep in mind that each diagnostic modality has advantages and limitations and choose an appropriate diagnostic strategy tailored for each patient.

Forward-viewing radial-array echoendoscope for staging of colon cancer beyond the rectum

AIM: To evaluate feasibility of the novel forward-viewing radial-array echoendoscope for staging of colon cancer beyond rectum as the first series.

METHODS: A retrospective study with prospectively entered database. From March 2012 to February 2013, a total of 21 patients (11 men) (mean age 64.2 years) with colon cancer beyond the rectum were recruited. The novel forward-viewing radial-array echoendoscope was used for ultrasonographic staging of colon cancer beyond rectum. Ultrasonographic T and N staging were recorded when surgical pathology was used as a gold standard.

RESULTS: The mean time to reach the lesion and the mean time to complete the procedure were 3.5 and 7.1 min, respectively. The echoendoscope passed through the lesions in 13 patients (61.9%) and reached the cecum in 10 of 13 patients (76.9%). No adverse events were found. The lesions were located in the cecum (n = 2), ascending colon (n = 1), transverse colon (n = 2), descending colon (n = 2), and sigmoid colon (n = 14). The accuracy rate for T1 (n = 3), T2 (n = 4), T3 (n = 13) and T4 (n = 1) were 100%, 60.0%, 84.6% and 100%, respectively. The overall accuracy rates for the T and N staging of colon cancer were 81.0% and 52.4%, respectively. The accuracy rates among traversable lesions (n = 13) and obstructive lesions (n = 8) were 61.5% and 100%, respectively. Endoscopic ultrasound and computed tomography had overall accuracy rates of 81.0% and 68.4%, respectively.

CONCLUSION: The echoendoscope is a feasible staging tool for colon cancer beyond rectum. However, accuracy of the echoendoscope needs to be verified by larger systematic studies.

Mini-probe ultrasonography for the staging of colon cancer: a systematic review and meta-analysis

AIM

With an increasing array of treatment modalities available for colon cancer, it is increasingly important to stage tumours accurately to allocate the appropriate management. This study evaluated the accuracy of mini-probe endoscopic ultrasound (EUS) in assigning clinical stage to colon cancer.

METHOD

An electronic search was performed in January 2013 using the Embase, MEDLINE and Cochrane databases. This was supplemented by a hand search of published abstracts from scientific meetings. Trials evaluating the accuracy of the mini-probe EUS compared with histopathological grade in determining the clinical stage of colon cancer were included in this pooled analysis. The main outcome measures included accuracy, sensitivity and specificity for T and N staging.

RESULTS

Ten studies were identified which compared the mini-probe EUS staging of 642 colon or rectal cancers with the histopathological specimen. The pooled sensitivity and specificity for staging were 0.91 and 0.98 for T1 tumours, 0.78 and 0.94 for T2 tumours, 0.97 and 0.90 for T3/T4 tumours and 0.63 and 0.82 for nodal staging. Eight per cent of T1/T2 tumours were upstaged to T3/T4 tumours and 5% of T3/T4 tumours were downstaged.

CONCLUSION

Mini-probe EUS is highly effective for assigning clinical stage in colon cancer and in identifying patients who may be suitable for nonsurgical treatment including neoadjuvant chemotherapy or endoscopic resection.

A miniature ultrasound probe is useful in reducing rebleeding after endoscopic cyanoacrylate injection for hemorrhagic gastric varices

OBJECTIVE

To better assess the usefulness of miniature ultrasound probe (MUP) sonography in the evaluation of the adequacy of gastric variceal injection with cyanoacrylate to decrease the risk of post injection rebleeding.

MATERIAL AND METHODS

Sixty-nine patients with bleeding gastric varices were included in this study. Endoscopic cyanoacrylate injection was performed in the acute phase for variceal hemostasis. After injection, patients (n = 34) included in the MUP group prospectively received endoscopic ultrasonography (EUS) with MUP during each scheduled endoscopic follow-up session. Patients (n = 35) in the control group who were included historically were followed up with the same interval with endoscopy only.

RESULTS

Four (11.4%) patients in the control group received reinjection, and there were 10 episodes of rebleeding in 7 (20.0%) patients. Nine (26.5%) patients received reinjection due to inadequate obturation as judged by EUS. There were six episodes of rebleeding in three (8.8%) patients in the MUP group. The free-of-rebleeding rate for the MUP group was significantly higher than that for the control group (p < 0.05). The cumulative survival for the MUP group was slightly better than that for the control group but was not statistically significant. The patients' compliance in both groups was similar. The endosonographers considered the performance of MUP sonography to be convenient.

CONCLUSIONS

MUP sonography is useful for the evaluation of the adequacy of tissue adhesive obturation of gastric varices that may reduce the probability of rebleeding.

A gasless laparoscopic technique of wide excision for gastric gastrointestinal stromal tumor versus open method

Background

Traditional open surgery for gastrointestinal stromal tumors (GIST) requires a long incision. Moreover, the gas-filling laparoscopic technique used in GIST surgery still has its limitations. Therefore, we developed a gasless laparoscopic (GL) surgery for GIST and compared it with traditional open surgery.

Methods

Between October 2007 and September 2009, 62 GIST patients in the National Taiwan University Hospital received wide excisions. Of these 62 patients, 30 underwent the new procedure (GL group) and 32 had open surgery (OS group). Preoperative and postoperative clinicopathologic characteristics were compared between the groups.

Results

There were no significant differences in preoperative characteristics or blood loss. However, the days to first flatus, postoperative hospital stay, wound length, white blood cell count at postoperative day one, and peak daily body temperature were all significantly improved in the GL group. Usage of postoperative analgesia on postoperative days one to five was also significantly lower in the GL group.

Conclusions

Wide-excision laparoscopy for gastric GIST can be performed more safely, more effectively, and with faster postoperative recovery using the gasless technique as compared with the open method. We, therefore, recommend this new surgical technique, which hybridizes the advantages of both the traditional open method and pure laparoscopic surgery.

Miniprobe endoscopic ultrasonography has limitations in determining the T stage in early colorectal cancer

Background/Aims

Mini-probe endoscopic ultrasonography (mEUS) is a useful diagnostic tool for accurate assessment of tumor invasion. The aim of this study was to estimate the accuracy of mEUS in patients with early colorectal cancer (ECC).

Methods

Ninety lesions of ECC underwent mEUS for pre-treatment staging. We divided the lesions into either the mucosal group or the submucosal group according to the mEUS findings. The histological results of the specimens were compared with the mEUS findings.

Results

The overall accuracy for assessing the depth of tumor invasion (T stage) was 84.4% (76/90). The accuracy of mEUS was significantly lower for submucosal lesions compared to mucosal lesions (p=0.003) and it was lower for large tumors (≥2 cm) (p=0.034). The odds ratios of large tumors and submucosal tumors affecting the accuracy of T staging were 3.46 (95% confidence interval [CI], 1.05 to 11.39) and 6.25 (95% CI, 1.85 to 25.14), respectively. When submucosal tumors were combined with large size, the odds ratio was 14.67 (95% CI, 1.46 to 146.96).

Conclusions

The overall accuracy of T stage determination with mEUS was considerably high in patients with ECC; however, the accuracy decreased when tumor size was >2 cm or the tumor had invaded the submucosal layer.

In vivo endoluminal ultrasound biomicroscopic imaging in a mouse model of colorectal cancer

RATIONALE AND OBJECTIVES

The gold-standard tool for colorectal cancer detection is colonoscopy, but it provides only mucosal surface visualization. Ultrasound biomicroscopy allows a clear delineation of the epithelium and adjacent colonic layers. The aim of this study was to design a system to generate endoluminal ultrasound biomicroscopic images of the mouse colon, in vivo, in an animal model of inflammation-associated colon cancer.

MATERIALS AND METHODS

Thirteen mice (Mus musculus) were used. A 40-MHz miniprobe catheter was inserted into the accessory channel of a pediatric flexible bronchofiberscope. Control mice (n = 3) and mice treated with azoxymethane and dextran sulfate sodium (n = 10) were subjected to simultaneous endoluminal ultrasound biomicroscopy and white-light colonoscopy. The diagnosis obtained with endoluminal ultrasound biomicroscopy and colonoscopy was compared and confirmed by postmortem histopathology.

RESULTS

Endoluminal ultrasound biomicroscopic images showed all layers of the normal colon and revealed lesions such as lymphoid hyperplasias and colon tumors. Additionally, endoluminal ultrasound biomicroscopy was able to detect two cases of mucosa layer thickening, confirmed by histology. Compared to histologic results, the sensitivities of endoluminal ultrasound biomicroscopy and colonoscopy were 0.95 and 0.83, respectively, and both methods achieved specificities of 1.0.

CONCLUSIONS

Endoluminal ultrasound biomicroscopy can be used, in addition to colonoscopy, as a diagnostic method for colonic lesions. Moreover, experimental endoluminal ultrasound biomicroscopy in mouse models is feasible and might be used to further develop research on the differentiation between benign and malignant colonic diseases.

Endoscopic ultrasonography (EUS) in preoperative staging of gastric cancer--demand and reality

Exact pretherapeutic staging is considered to be essential for decision-making in the therapeutic algorithm of gastric cancer. THE AIM OF THE STUDY was to characterize the role and value of EUS in the diagnostic and therapeutic management of gastric cancer in daily surgical practice.

MATERIAL AND METHODS

Thousand one hundred thirty nine patients with primary gastric cancer from 80 hospitals of each profile of care were enrolled in this systematic clinical prospective multicenter observational study over a time period of 12 months. The characteristics of the diagnostic management, in particular, of EUS were documented. The preoperative EUS findings were compared with the T stage (T1 to T4) and the N category (N+ or N-) revealed by the histopathologic investigation of the surgical specimen. By the mean of χ² test, the impact of EUS on the therapeutic decision-making was determined.

RESULTS

Pretherapeutic EUS was only performed in 27.4% (n=312) of all patients. Overall, the diagnostic accuracy for the T stage was 42.6% in average. The subgroup analysis showed the following results: T1, 31.5%; T2, 42.6%; T3, 65.2%; T4, 17.6%. The correct predictive value of the N category was 71.3% reaching a sensitivity of 69.7% and a specificity of 73.3%. Overstaging was observed in 45.8%, understaging in only 10.8%. Additional diagnostic information by EUS was only provided in 4.7% of subjects.

CONCLUSIONS

The present study indicates the variability, limited reliability and only moderate acceptance of EUS in diagnosing gastric cancer in daily practice. In particular, the prediction of the T stage does not reach the data reported in the literature, which were mostly achieved in specific EUS studies.

EUS for the staging of gastric cancer: a meta-analysis

BACKGROUND

The role of EUS in the locoregional staging of gastric carcinoma is undefined.

OBJECTIVE

We aimed to comprehensively review and quantitatively summarize the available evidence on the staging performance of EUS.

DESIGN

We systematically searched the MEDLINE, Cochrane, CANCERLIT, and EMBASE databases for relevant studies published until July 2010.

SETTING

Formal meta-analysis of diagnostic accuracy parameters was performed by using a bivariate random-effects model.

PATIENTS

Fifty-four studies enrolling 5601 patients with gastric cancer undergoing disease staging with EUS were eligible for the meta-analysis.

MAIN OUTCOME MEASUREMENTS

EUS staging accuracy across eligible studies was measured by computing overall sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR).

RESULTS

EUS can differentiate T1-2 from T3-4 gastric cancer with high accuracy, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.86 (95% CI, 0.81-0.90), 0.91 (95% CI, 0.89-0.93), 9.8 (95% CI, 7.5-12.8), 0.15 (95% CI, 0.11-0.21), and 65 (95% CI, 41-105), respectively. In contrast, the diagnostic performance of EUS for lymph node status is less reliable, with overall sensitivity, specificity, PLR, NLR, and DOR of 0.69 (95% CI, 0.63-0.74), 0.84 (95% CI, 0.81-0.88), 4.4 (95% CI, 3.6-5.4), 0.37 (95% CI, 0.32-0.44), and 12 (95% CI, 9-16), respectively. Results regarding single T categories (including T1 substages) and Bayesian nomograms to calculate posttest probabilities for any target condition prevalence are also provided.

LIMITATIONS

Statistical heterogeneity was generally high; unfortunately, subgroup analysis did not identify a consistent source of the heterogeneity.

CONCLUSIONS

Our results support the use of EUS for the locoregional staging of gastric cancer, which can affect the therapeutic management of these patients. However, clinicians must be aware of the performance limits of this staging tool.

Recent advances in preoperative staging of gastric cancer

A more differentiated therapy regimen for gastric carcinoma requires more precise preoperative staging. In patients with early gastric cancer (EGC), especially in cases with carcinoma confined to mucosa, endoscopic resection (ER) is usually performed to avoid unnecessary surgical procedures. To achieve R0 resection for locally advanced gastric cancer (AGC), neoadjuvant treatments have been investigated. Clinical staging of gastric cancer has been greatly improved by advances in imaging techniques, such as endoscopic ultrasonography (EUS), transabdominal ultrasonography (TAUS), multi-slice spiral CT (MSCT), magnetic resonance imaging (MRI), positron emission tomography (PET), combined PET-CT scans, and laparoscopic staging. This paper aims to summarize the recent advances in preoperative staging of gastric cancer.

Is endoscopic ultrasonography indispensable in patients with early gastric cancer prior to endoscopic resection?

BACKGROUND

Endoscopic resection as curative treatment of early gastric cancer (EGC) requires accurate staging for depth of invasion (T) before therapy. This study aimed to compare T staging of EGC using a miniprobe with that of conventional endoscopy (CE).

METHODS

A total of 388 patients with suspected of EGC by CE were prospectively enrolled in the study. After miniprobe staging by an experienced endosonographer, CE staging was performed by another endoscopist who was blinded to the miniprobe assessment. Patients underwent either endoscopic resection (n = 325) or surgery (=63) according to staging results. Results of each method were compared with the histology of the resected specimen. Clinicopathological factors affecting accuracy of each test were also evaluated.

RESULTS

Overall accuracy of miniprobe and CE staging was 78.9% (306/388) and 81.4% (316/388), respectively (p = 0.052). Sensitivity for T1m was more than 95% (miniprobe 98.7%, CE 97.7%), whereas sensitivity for T1sm was lower at 6.6% for miniprobe and 23.7% for CE (p = 0.002). Among nine lesions identically considered submucosal invasion by both methods, three were T1sm cancer. Diagnostic accuracy of the miniprobe was lower than that of CE with respect to lesions located in the lower third of the stomach, differentiated histology, or massive submucosal invasion.

CONCLUSIONS

Overall accuracy of the miniprobe and CE for T staging in EGC was approximately 80% with no significant difference. Accurate prediction of both techniques for submucosal invasion was poor, even by using a combination of the two methods. The use of the miniprobe may not increase the positive predictive value for T staging over the use of CE alone.

Endosonographic staging of lower intestinal malignancy

The use of EUS in the assessment of rectal pathology is well established. The accurate staging of lower intestinal tumours predicts prognosis and guides the planning of individual patient treatment. Increased experience and the development of high resolution three-dimensional EUS has lead to the greater accuracy of rectal staging with EUS of rectal tumours now considered the gold standard showing T stage accuracy that ranges from 75% to 95%, with N stage accuracy ranging from 65% to 80%. The use of EUS in the staging of colonic pathology, however, is not so well established though advances in miniprobe EUS has improved the assessment of colonic tumours. EUS is also of benefit in the assessment of anal pathology though here, accurate correlation with histology has not been firmly established.

The accuracy of endoscopic ultrasonography in differentiating mucosal from deeper gastric cancer

BACKGROUND AND AIM

With the advent of endoscopic mucosal resection and endoscopic submucosal dissection techniques, pretreatment differentiation between mucosal and deeper gastric cancer has become increasingly important. The aim of this study was to systematically review published data on the diagnostic performance of endoscopic ultrasonography (EUS) in differentiating between mucosal and deeper gastric cancer.

METHODS

A systematic search for relevant studies was performed of the PubMed/MEDLINE and Embase databases. Two reviewers independently assessed the methodological quality of each study. Sensitivity and specificity of EUS were calculated for each study and a summary receiver operating characteristic curve (sROC) was constructed. Subgroup analyses were performed if results of individual studies were heterogeneous.

RESULTS

The inclusion criteria were met by 18 studies. The studies had poor methodological quality. Sensitivity and specificity of EUS in detecting cancerous extension beyond the mucosa ranged from 18.2 to 100% (median 87.8%) and from 34.7 to 100% (median 80.2%), with an area under the sROC of 0.8924. There was significant heterogeneity in both sensitivities and specificities among the included studies (P < 0.0001). Studies which only included patients endoscopically suspected of having EGC and studies which only used transducer frequencies > or =15 MHz were homogeneous in sensitivities (P= 0.1828 and 0.4501, respectively).

CONCLUSION

It is unclear yet whether EUS can accurately differentiate between mucosal and deeper gastric cancer. Factors that may influence its diagnostic performance should be further explored.

Impact of endoscopic ultrasonography (EUS) on surgical decision-making in upper gastrointestinal tract cancer: an international multicenter study

BACKGROUND

Endoscopic ultrasonography (EUS) is an integrated part of the pretherapeutic evaluation program for patients with upper gastrointestinal (GI) tract cancer. Whether the clinical impact of EUS differs between surgeons from different countries is unknown. The same applies to the potential clinical influence of EUS misinterpretations. The aim of this study was to evaluate the interobserver agreement on predefined treatment strategies between surgeons from four different countries, with and without EUS, and to evaluate the clinical consequences of EUS misinterpretations.

METHODS

One hundred patients with upper GI tract cancer were randomly selected from all upper GI tract cancer patients treated at Odense University Hospital between 1997 and 2000. Based on patient records and EUS database results, a case story was created with and without the EUS result for each patient. Four surgeons were asked to select the relevant treatment strategy in each case, at first without knowledge of the EUS and thereafter with the EUS result available. Interobserver agreement and impact of EUS misinterpretations were evaluated using the actual final treatment of each patient as reference.

RESULTS

Three of four or all four surgeons agreed on the same treatment strategy for nearly 60% of the patients with and without the EUS results. Treatment decisions were changed in 34% based on the EUS results, and the majority of these changes were toward nonsurgical and palliative treatments (85%). Interobserver agreement was relatively low, but overall EUS increased kappa values from 0.16 ("poor") to 0.33 ("fair"), thus indicating increased overall agreement after the EUS results were available. EUS conclusion regarding stage or resectability was wrong in 17% of the cases, but only one serious event would have been the clinical result of EUS misinterpretations.

CONCLUSION

Despite being used in different ways by different surgeons, EUS did change patient management in one third of the cases. The impact of EUS misinterpretations seemed very low, and this study confirmed one of the strongest clinical possibilities of EUS, i.e., the ability to detect nonresectable cases. EUS is an important imaging modality for oncosurgeons from different countries.

Population-based analyses of lymph node metastases in colorectal cancer

BACKGROUND & AIMS

The potential presence of lymph node metastases in patients with colorectal cancer (CRC) limits the application of minimally invasive techniques of resection. We used data from the National Cancer Institute's Surveillance, Epidemiology, and End Results registry to better understand the underlying risk of lymph node metastases and factors that influence this risk in a population-based fashion.

METHODS

In a cohort of 124,180 CRC patients diagnosed from 1988 through 2002 treated with radical surgery without neoadjuvant irradiation, we assessed the proportion of patients who were lymph node positive and determined factors that influenced the risk of lymph node metastases including patient characteristics, anatomic location, and histopathologic factors.

RESULTS

Among all patients, the proportion of lymph node metastases was 34.5%. The overall proportion of node positivity was 8% for T1 tumors, 18.5% for T2 tumors, 42% for T3 tumors, and 50% for T4 tumors. Nodal metastases were noted in 7% of proximal T1 colon tumors, 7.5% of distal T1 colon tumors, and 10.1% of T1 rectal tumors. Patients with poorly differentiated tumors were much more likely to be node positive (52%) than patients with well-differentiated tumors (20%) (P<.0001).

CONCLUSIONS

Even patients with superficial CRCs have a significant risk of nodal metastases. This risk should be considered when balancing the risks and benefits of minimally invasive techniques such as local excision or endoscopic resection for the treatment of CRC.