Role of magnifying endoscopy with narrow-band imaging in the diagnosis of noninvasive gastric neoplasia.

BACKGROUND AND AIM: There are no globally approved, distinguishing criteria enabling the classification of gastric adenomas and intramucosal carcinomas for differential diagnosis of noninvasive neoplasia (NIN). METHODS: Next-generation sequencing of 50 cancer-related genes was undertaken on 68 pathologically diagnosed microdissected gastric neoplasms (25 adenomas, 27 intramucosal carcinomas, and 16 submucosal carcinomas) obtained during endoscopic submucosal dissection. Findings from magnifying endoscopy with narrow-band imaging (M-NBI) of 52 NINs (the 25 adenomas and 27 intramucosal carcinomas) were compared with these data. RESULTS: Among all 68 neoplasms, the most frequently mutated genes were APC (76% in adenoma, 11.1% in intramucosal carcinoma, and 0% in submucosal carcinoma; P < 0.001) and TP53 in intramucosal and submucosal carcinomas (8% in adenoma, 48.1% in intramucosal carcinoma, and 75% in submucosal carcinoma; P < 0.001). Dividing the NIN neoplasms into five groups according to their mutational status (A1: APC mutation, A2: APC + α mutation, B: APC + TP53 mutation, C: TP53 mutation, D: no mutation in either APC or TP53) resulted in almost identical diagnoses by pathology and M-NBI for groups A1 (12/13, 92%), C (12/13, 92%), and D (16/17, 94%) but not for groups A2 (3/7, 43%) or B (0/2, 0%). This finding implies that NINs with the APC + α mutation have carcinoma-like endoscopic features despite most being judged as adenomas by pathology. CONCLUSION: A diagnosis of NINs by pathology or M-NBI in the subset of gastric tumors classified by cancer-related mutations is not completely identical, suggesting the possible additional role of M-NBI in diagnosing NINs. Further studies are needed to confirm this.

Identification of early genetic changes in well-differentiated intramucosal gastric carcinoma by target deep sequencing.

BACKGROUND AND AIMS: The recent advancement of next-generation sequencing (NGS) has enabled the identification of cancer-related somatic aberrations in advanced gastric cancer. However, these remain unclear in early gastric cancers, especially in intramucosal gastric cancers. PATIENTS AND METHODS: Thirty-one well-differentiated (tub1) intramucosal gastric cancers obtained by endoscopic submucosal dissection (ESD) from 29 patients were analyzed. After precise collection of tumors and non-tumors from formalin-fixed paraffin-embedded tissues using laser-captured microdissection (LCM), target sequencing analysis of 50 cancer-related genes was performed using an Ion-Proton sequencer. RESULTS: The most frequent hotspot mutation was found in TP53 (17 lesions, 54.8%) followed by the Wnt-signaling pathway genes, APC and CTNNB1 (6 lesions, 19.4%). The mutations in TP53 and the Wnt-signaling genes were mutually exclusive (p = 0.004). There was a tendency that H. pylori infection (p = 0.082) and macroscopic protrusion (p = 0.095) was associated with the presence of these mutations. Only 10 lesions (59%) among 17 lesions with proven TP53 mutations were positive for p53 immunostaining demonstrating the superiority of the mutational analysis. In addition, focal gene amplification of ERBB2 (16%) was found frequently in these early stage lesions. CONCLUSIONS: Using LCM and NGS, mutations in TP53 and the Wnt-signaling pathway were frequently found and were mutually exclusive in the earliest stage of gastric carcinogenesis.

Target sequencing of cancer-related genes in early esophageal squamous neoplasia resected by endoscopic resection in Japanese patients.

BACKGROUND AND AIMS: Next generation sequencing (NGS) has revealed a great deal about cancer-related somatic changes in esophageal squamous cell neoplasia; however, the changes in the very early stages remain unclear. RESULTS: TP53 (87%) and CDKN2A (20%) hot spot mutations were frequently found in early lesions. TP53 was the most common mutation (LGIN/HGIN, 86%; EP, 83%; LPM, 95%; MM/SM1, 80%), followed by CDKN2A (29%, 28%, 16% and 10%, respectively); the frequency of other mutations increased as the disease advanced (p < 0.01). Copy number variation analysis revealed copy number aberrations in multiple genes, including PIK3CA amplification (48%). NGS was superior to p53 immunostaining for detecting TP53 mutations (74% vs. 87%); in combination, the two tests improved detectability to 94%. Clinically, smoking was associated with the occurrence of TP53 mutations in these early lesions (p = 0.049). MATERIALS AND METHODS: Fifty-four early esophageal neoplasia lesions from 47 patients treated by endoscopic resection (low-grade intraepithelial neoplasia [LGIN], n = 1; high-grade intraepithelial neoplasia [HGIN] n = 7; invasion limited to epithelium [EP/M1], n = 18; lamina propria mucosae [LPM/M2], n = 19; muscularis mucosae [MM/M3], n = 8; and upper third of the SM [SM1], n = 2) were isolated from formalin-fixed paraffin-embedded tissue specimens by laser-capture microdissection. Target sequencing of 50 cancer-related genes was performed with an Ion Proton sequencer; their association with the clinical characteristics was investigated. CONCLUSIONS: Mutations of TP53 and CDKN2A, and PIK3CA amplification were common in early esophageal squamous neoplasia, while other mutations accumulated with disease progression. An understanding of these molecular events might provide a molecular basis for early lesion treatment.

Stratifying the risk of lymph node metastasis in undifferentiated-type early gastric cancer.

AIM: To study how lymph node metastasis (LNM) risk is stratified in undifferentiated-type early gastric cancer (undiff-EGC) dependent on combinations of risk factors. METHODS: Five hundred and sixty-seven cases with undiff-EGC undergoing gastrectomy with lymphadenectomy were examined retrospectively. Using clinicopathological factors of patient age, location, size, an endoscopic macroscopic tumor form, ulceration, depth, histology, lymphatic involvement (LI) and venous involvement (VI), LNM risk was examined and stratified by conventional statistical analysis and data-mining analysis. RESULTS: LNM was positive in 44 of 567 cases (7.8%). Univariate analysis revealed > 2 cm, protrusion, submucosal (sm), mixed type, LI and VI as significant prognostic factors and > 2 cm and LI-positive were independent factors by multivariate analysis. In preoperatively evaluable factors excluding LVI, sm and > 2 cm were independent factors. According to the depth and size, cases were categorized into the low-risk group [m and ≤ 2 cm, 0% (LNM incidence)], the moderate-risk group (m and > 2 cm, 5.6%; and sm and ≤ 2 cm, 6.0%), and the high-risk group (sm and > 2 cm, 19.3%). On the other hand, LNM occurred in 1.4% in all LI-negative cases, greatly lower than 28.2% in all LI-positive cases, and LNM incidence was low in LI-negative cases even in the moderate- and high-risk groups. CONCLUSION: LNM-related factors in undiff-EGC were depth and size preoperatively while those were LI and size postoperatively. Among these factors, LI was the most significantly correlated factor.

Deep-sequencing analysis of the association between the quasispecies nature of the hepatitis C virus core region and disease progression.

Variation of core amino acid (aa) 70 of hepatitis C virus (HCV) has been shown recently to be closely correlated with liver disease progression, suggesting that the core region might be present as a quasispecies during persistent infection and that this quasispecies nature might have an influence on the progression of disease. In our investigation, the subjects were 79 patients infected with HCV genotype 1b (25 with chronic hepatitis [CH], 29 with liver cirrhosis [LC], and 25 with hepatocellular carcinoma [HCC]). Deep sequencing of the HCV core region was carried out on their sera by using a Roche 454 GS Junior pyrosequencer. Based on a plasmid containing a cloned HCV sequence (pCV-J4L6S), the background error rate associated with pyrosequencing, including the PCR procedure, was calculated as 0.092 ± 0.005/base. Deep sequencing of the core region in the clinical samples showed a mixture of "mutant-type" Q/H and "wild-type" R at the core aa 70 position in most cases (71/79 [89.9%]), and the ratio of mutant residues to R in the mixture increased as liver disease advanced to LC and HCC. Meanwhile, phylogenetic analysis of the almost-complete core region revealed that the HCV isolates differed genetically depending on the mutation status at core aa 70. We conclude that the core aa 70 mixture ratio, determined by deep sequencing, reflected the status of liver disease, demonstrating a significant association between core aa 70 and disease progression in CH patients infected with HCV genotype 1b.