Endoscopic Ultrasonography for Pretreatment T-staging of Gastric Cancer: An Accuracy and Discrepancy Analysis

In the current era of multi-disciplinary treatment, precise and detailed diagnosis prior to treatment is crucial for clinical practice. For different lesions that fit different indications, the optimum approach for treatment differs significantly. Thus, the recent 8th American Joint Committee on Cancer classification system has introduced 'clinical stage' as a criterion. Endoscopic ultrasonography (EUS) has been the first-line choice for pretreatment staging; however, there is no standardization of the depth classification nor a standard EUS method. Additionally, the accuracy for this diagnostic test has ranged between <40 and 90% in previous studies. The aim of the present study was to determine the accuracy of EUS, identify the discrepancies between EUS and histological results, and analyze the underlying causes. Between June 2014 and February 2016, EUS was performed on gastric carcinoma specimens from 60 consecutive patients. EUS was performed on the resected specimens following surgery, but prior to fixation in formalin, invasion of the gastric wall was determined and the deepest location was marked with sutures. The ultrasound images were independently interpreted, and the quality of the images was scored by two endoscopists. Subsequently, the ultrasound images were compared with the pathological results of the same section. The overall accuracy of EUS was 75%. For locally advanced gastric cancers, EUS had a relatively high accuracy (33/43, 86%). The EUS results corresponded well with the pathological hematoxylin and eosin staining results, and the deepest points determined by EUS were confirmed by pathology in the majority of cases (85%). In total, 50 and 10 cases were scored as having high/moderate and low quality, associated with accuracies of 86% (43/50) and 20% (2/10), respectively. EUS is valuable for pretreatment T-staging, particularly for advanced cases. Proximal stomach cancer exhibited a tendency for improved accuracy. Overall, the results of the present study suggest that standardized scanning processes, particularly including all-encompassing scanning, proper probe-placement and high image quality, lead to improved accuracy of EUS.