Gastric cancers emerging after H. pylori eradication arise exclusively from non-acid-secreting areas

Chronological Changes in the Gastric Cancer Subsite in Akita, Japan: The Trends from the Data of a Hospital-Based Registration System

With the decreasing global trend in the Helicobacter pylori infection rate, compositional changes in the gastric cancer subsites have occurred worldwide. However, the compositional changes in Asian countries, including Japan, remain to be clarified. The aim of this study is to investigate the latest chronological changes in the gastric cancer subsite using a hospital-based registration system in Akita prefecture in Japan. From 2007-2015, subsites of gastric cancers were coded according to the International Classification of Diseases for Oncology (ICD-03). The nine-year registration period was divided into the three 3-year periods: 2007-2009, 2010-2012, and 2013-2015. A total of 10,804 cases of gastric cancer were registered. The proportion of cardiac cancer among total gastric cancer slightly but significantly declined from 12.1% in 2007-2009 to 9.2% in 2013-2015 (P < 0.01). Among non-cardia cancer, the proportion of corpus cancer significantly increased from 41.3% to 50.2% during the study period (P < 0.01), while that of antropylorus cancer significantly decreased from 37.6% to 34.3% (P < 0.05). Such compositional changes in the gastric cancer subsite were observed largely in men, regardless of the histologic subtype of cancer. With the decreasing H. pylori infection rate, compositional changes in the gastric cancer subsite are occurring in Japan. While the proportion of cardia and antropylorus cancer is declining, that of corpus cancer is increasing, indicating diverse etiology of gastric carcinogenesis depending on the subsites. Identifying the most common sites of occurrence, may help to improve the efficiency of screening for gastric cancer.

Usefulness of Endoscopic Imaging to Visualize Regional Alterations in Acid Secretion of Noncancerous Gastric Mucosa after Helicobacter pylori Eradication

Purpose

Endoscopic diagnosis of gastric cancer (GC) that emerges after eradication of Helicobacter pylori may be affected by unique morphological changes. Using comprehensive endoscopic imaging, which can reveal biological alterations in gastric mucosa after eradication, previous studies demonstrated that Congo red chromoendoscopy (CRE) might clearly show an acid non-secretory area (ANA) with malignant potential, while autofluorescence imaging (AFI) without drug injection or dyeing may achieve early detection or prediction of GC. We aimed to determine whether AFI might be an alternative to CRE for identification of high-risk areas of gastric carcinogenesis after eradication.

Materials and Methods

We included 27 sequential patients with metachronous GC detected during endoscopic surveillance for a mean of 82.8 months after curative endoscopic resection for primary GC and eradication. After their H. pylori infection status was evaluated by clinical interviews and ¹³C-urea breath tests, the consistency in the extension of corpus atrophy (e.g., open-type or closed-type atrophy) between AFI and CRE was investigated as a primary endpoint.

Results

Inconsistencies in atrophic extension between AFI and CRE were observed in 6 of 27 patients, although CRE revealed all GC cases in the ANA. Interobserver and intraobserver agreements in the evaluation of atrophic extension by AFI were significantly less than those for CRE.

Conclusions

We demonstrated that AFI findings might be less reliable for the evaluation of gastric mucosa with malignant potential after eradication than CRE findings. Therefore, special attention should be paid when we clinically evaluate AFI findings of background gastric mucosa after eradication (University Hospital Medical Information Network Center registration number: UMIN000020849).

Pathogenesis and risk factors for gastric cancer after Helicobacter pylori eradication

Helicobacter pylori (H. pylori) infection was thought to be the main cause of gastric cancer, and its eradication showed improvement in gastric inflammation and decreased the risk of gastric cancer. Recently, a number of studies reported the occurrence of gastric cancer after successful eradication. Patients infected with H. pylori, even after eradication, have a higher risk for the occurrence of gastric cancer when compared with uninfected patients. Metachronous gastric cancer occurs frequently following the endoscopic removal of early gastric cancer. These data indicate that metachronous cancer leads to the occurrence of gastric cancer even after successful eradication of H. pylori. The pathogenesis of this metachronous cancer remains unclear. Further research is needed to identify biomarkers to predict the development of metachronous gastric cancer and methods for gastric cancer screening. In this article, we review the role of the H. pylori in carcinogenesis and the histological and endoscopic characteristics and risk factors for metachronous gastric cancer after eradication. Additionally, we discuss recent risk predictions and possible approaches for reducing the risk of metachronous gastric cancer after eradication.

Alterations of the TP53 gene in gastric and esophageal carcinogenesis

TP53 genes is one of more important tumor suppressor gene, which acts as a potent transcription factor with fundamental role in the maintenance of genetic stability. The development of esophageal and gastric cancers is a multistep process resulting in successive accumulation of genetic alterations that culminates in the malignant transformation. Thus, this study highlights the participation of the main genetic alterations of the TP53 gene in esophageal and gastric carcinogenesis. Among these changes, high frequency of TP53 mutations, loss of heterozygosity (LOH), overexpression of the p53 protein, and consequently loss of p53 function, which would be early events in esophageal and gastric cancers, as well as an important biomarker of the prognosis and treatment response. Furthermore, Single Nucleotide Polymorphisms (SNPs) of TP53 have been implicated in the development and prognosis of several cancers, mainly TP53 codon 72 polymorphism whose role has been extensively studied in relation to susceptibility for esophageal and gastric cancer development.