Background: Epithelial–mesenchymal transition (EMT) plays a significant role in tumor progression and invasion. Snail is a known regulator of EMT in various malignant tumors. This study investigated the role of Snail in gastric cancer.Methods: We examined the effects of silenced or overexpressed Snail using lenti-viral constructs in gastric cancer cells. Immunohistochemical analysis of tissue microarrays from 314 patients with gastric adenocarcinoma (GC) was used to determine Snail’s clinicopathological and prognostic significance. Differential gene expression in 45 GC specimens with Snail overexpression was investigated using cDNA microarray analysis.Results: Silencing of Snail by shRNA decreased invasion and migration in GC cell lines. Conversely, Snail overexpression increased invasion and migration of gastric cancer cells, in line with increased VEGF and MMP11. Snail overexpression (≥75% positive nuclear staining) was also significantly associated with tumor progression (P < 0.001), lymph node metastases (P = 0.002), lymphovascular invasion (P = 0.002), and perineural invasion (P = 0.002) in the 314 GC patients, and with shorter survival (P = 0.023). cDNA microarray analysis revealed 213 differentially expressed genes in GC tissues with Snail overexpression, including genes related to metastasis and invasion.Conclusion: Snail significantly affects invasiveness/migratory ability of GCs, and may also be used as a predictive biomarker for prognosis or aggressiveness of GCs.

Background: Endoscopic treatments, such as endoscopic submucosal dissection (ESD) and laparoscopic gastrectomy, are increasingly used to treat a subset of patients with early gastric cancer (EGC). To achieve successful outcomes, it is very important to accurately determine the lateral extent of the tumor. Therefore, we investigated the diagnostic performance of chromoendoscopy using indigo carmine dye added to acetic acid (AI chromoendoscopy) in delineating differentiated or undifferentiated adenocarcinomas in patients with EGC. Methods: We prospectively included 151 lesions of 141 patients that had an endoscopic diagnosis of EGC. All the lesions were examined by conventional endoscopy and AI chromoendoscopy before ESD or laparoscopic gastrectomy. The border clarification between the lesion and the normal mucosa was classified as distinct or indistinct before and after AI chromoendoscopy. Results: The borders of the lesions were distinct in 66.9% (101/151) with conventional endoscopy and in 84.1% (127/151) with AI chromoendoscopy (P < 0.001). Compared with conventional endoscopy, AI chromoendoscopy clarified the border in a significantly higher percentage of differentiated adenocarcinomas (74/108 [68.5%] vs 97/108 [89.8%], respectively, P < 0.001). However, the border clarification rate for undifferentiated adenocarcinomas did not differ between conventional endoscopy and AI chromoendoscopy (27/43 [62.8%] vs 30/43 [70.0%], respectively, P = 0.494). Conclusions: AI chromoendoscopy is useful in determining the lateral extent of EGCs. However, its usefulness is reduced in undifferentiated adenocarcinomas.

Endoscopic ultrasonography (EUS) is a valuable imaging tool for evaluating subepithelial lesions in the stomach. However, there are few studies on differentiation between gastrointestinal stromal tumors (GISTs) and benign mesenchymal tumors, such as leiomyoma or schwannoma, with the use of EUS. In addition, there are limitations in the analysis of the characteristic features of such tumors due to poor interobserver agreement as a result of subjective interpretation of EUS images. Therefore, the aim of this study was to evaluate the role of digital image analysis in distinguishing the features of GISTs from those of benign mesenchymal tumors on EUS. We enrolled 65 patients with histopathologically proven gastric GIST, leiomyoma or schwannoma on surgically resected specimens who underwent EUS examination at our endoscopic unit from January 2007 to September 2010. After standardization of the EUS images, brightness values including the mean (T_mean), indicative of echogenicity, and the standard deviation (T_SD), indicative of heterogeneity, in the tumors were analyzed. The T_mean and T_SD were significantly higher in GIST than in leiomyoma and schwannoma (p < 0.001). However, there was no significant difference in the T_mean or T_SD between benign and malignant GISTs. The sensitivity and specificity were almost optimized for differentiating GIST from leiomyoma or schwannoma when the critical values of T_mean and T_SD were 65 and 75, respectively. The presence of at least 1 of these 2 findings in a given tumor resulted in a sensitivity of 94%, specificity of 80%, positive predictive value of 94%, negative predictive value of 80%, and accuracy of 90.8% for predicting GIST. Digital image analysis provides objective information on EUS images; thus, it can be useful in diagnosing gastric mesenchymal tumors.

The prognosis of a gastrointestinal stromal tumor (GIST) is influenced by its anatomic site; however, few studies on the prognosis of gastric GISTs have been reported. The aims of this study were to evaluate long-term prognoses of patients who underwent surgical resection for gastric GISTs and to compare the clinical efficacy of two staging systems: the National Institutes of Health (NIH) consensus criteria and the 7th Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) tumor-node-metastasis (TNM) staging system. We conducted a retrospective observational study of 145 patients who underwent surgical resection for gastric GISTs between February 2001 and June 2012 at Pusan National University Hospital (Busan, Korea). Recurrence and 5-year recurrence-free survival (RFS) rates were analyzed. During a median follow-up period of 44 months (range, 6–144 months), 11 recurrent lesions were detected in 9 patients (6.4%). On multivariate analysis, tumor size (>5 cm), mitotic count (>5/50 high-power fields), and epithelioid and mixed pathological type were significantly associated with recurrence. The overall 5-year RFS rate was 93.4%. Although no statistically significant differences were detected (C-statistic difference P = 0.886), all metrics showed lower values for the UICC/AJCC TNM staging system than for the NIH consensus criteria, suggesting that the UICC/AJCC TNM staging system may be a better model. The 5-year RFS rate in patients who underwent curative resection for gastric GISTs was excellent. The UICC/AJCC TNM staging system may be more useful than the NIH consensus criteria for risk categorization of patients with gastric GISTs.

Background: This systematic review and meta-analysis investigated the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or PET/computed tomography (PET/CT) for the detection of disease recurrence after curative resection of gastric cancer. Methods: The PubMed and Embase databases, from the earliest available date of indexing through November 30, 2019, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT to detect recurrent disease after gastric cancer surgery.Results: Across 17 studies (1,732 patients), the pooled sensitivity for F-18 FDG PET or PET/CT was 0.82 (95% confidence interval [CI], 0.74–0.88) with heterogeneity of I2=76.5 (p<0.001), and the specificity was 0.86 (95% CI, 0.78–0.91) with heterogeneity of I2=94.2 (p<0.001). Likelihood ratio (LR) tests gave an overall positive LR of 6.0 (95% CI, 3.6–9.7) and negative LR of 0.2 (95% CI, 0.14–0.31). The pooled diagnostic odds ratio was 29 (95% CI, 13–63). The summary receiver operating characteristic curve indicates that the area under the curve was 0.91 (95% CI, 0.88–0.93). Conclusion: The current meta-analysis showed good sensitivity and specificity of F-18 FDG PET or PET/CT for detecting recurrent disease after curative resection of gastric cancer despite heterogeneity in ethnicity, recurrence rate, histology, and interpretation method.