Accumulation of aberrant DNA methylation in normal-appearing gastric mucosae, mostly induced by H. pylori infection, is now known to be deeply involved in predisposition to gastric cancers (epigenetic field defect), and silencing of protein-coding genes has been analyzed so far. In this study, we aimed to clarify the involvement of microRNA (miRNA) gene silencing in the field defect. First, we selected three miRNA genes as methylation-silenced after analysis of six candidate ''methylation-silenced'' tumor-suppressor miRNA genes. Methylation levels of the three genes (miR124a-1, miR-124a-2 and miR-124a-3) were quantified in 56 normal gastric mucosae of healthy volunteers (28 volunteers with H. pylori and 28 without), 45 noncancerous gastric mucosae of gastric cancer patients (29 patients with H. pylori and 16 without), and 28 gastric cancer tissues (13 intestinal and 15 diffuse types). Among the healthy volunteers, individuals with H. pylori had 7.8-13.1-fold higher methylation levels than those without (p < 0.001). Among individuals without H. pylori, noncancerous gastric mucosae of gastric cancer patients had 7.2-15.5-fold higher methylation levels than gastric mucosae of healthy volunteers (p < 0.005). Different from protein-coding genes, individuals with past H. pylori infection retained similar methylation levels to those with current infection. In cancer tissues, methylation levels were highly variable, and no difference was observed between intestinal and diffuse histological types. This strongly indicated that methylationsilencing of miRNA genes, in addition to that of protein-coding genes, contributed to the formation of a field defect for gastric cancers. ' 2008 Wiley-Liss, Inc.Key words: field for cancerization; microRNA; methylation; gastric cancer; Helicobacter pylori Metachronous occurrence of gastric cancers is becoming an important issue as localized resection of early gastric cancers by endoscopic submucosal dissection (ESD) has become common. 1 The incidence of secondary primary gastric cancers after ESD reaches as high as 2.0% per year 2 whereas the incidence of gastric cancer in the general Japanese population is 0.14% per year. 3 This indicates that noncancerous gastric mucosae are already predisposed to developing gastric cancers, forming a field defect (field for cancerization). High incidences of metachronous cancers have been known not only for gastric cancers but also for bladder, liver, and esophageal cancers 4-6 and are becoming recognized for lung, breast and colorectal cancers. [7][8][9] A molecular basis for the field defect has been considered as an accumulation of genetic and epigenetic alterations in normalappearing tissues. Traditionally, cells with a genetic alteration were considered to form a physically continuous patch, producing a genetically altered field. 10 Recently, we found that aberrant DNA methylation of specific genes can be induced in as high as several percentage of cells in noncancerous gastric mucosae (thus in multiple independent gastric glands), and the degre...

Accumulated evidence has revealed that endoscopic ultrasonography (EUS) has had a great impact on the clinical evaluation of pancreatic cancers. EUS can provide high-resolution images of the pancreas with a quality regarded as far surpassing that achieved on transabdominal ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI). EUS is particularly useful for the detection of small pancreatic lesions, while EUS and its related techniques such as contrast-enhanced EUS (CE-EUS), EUS elastography, and EUS-guided fine needle aspiration (EUS-FNA) are also useful in the differential diagnosis of solid or cystic pancreatic lesions and the staging (T-staging, N-staging, and M-staging) of pancreatic cancers. In the diagnosis of pancreatic lesions, CE-EUS and EUS elastography play a complementary role to conventional EUS. When sampling is performed using EUS-FNA, CE-EUS and EUS elastography provide information on the target lesions. Thus, conventional EUS, CE-EUS, EUS elastography, and EUS-FNA are essential in the clinical investigation of pancreatic cancer.

Our study investigated the relationship between gastric cancer development and activity of Helicobacter pylori-associated chronic gastritis or the resulting chronic atrophic gastritis (CAG). A cohort of 4,655 healthy asymptomatic subjects, in whom serum pepsinogen (PG) and H. pylori antibody titer had been measured to assess the activity and stage of H. pylori-associated chronic gastritis, was followed for up to 16 years, and cancer development was investigated. In subjects with a serologically diagnosed healthy stomach (H. pylori-negative/CAG-negative), cancer incidence rate was low, at 16/100,000 person-years. With the establishment of H. pylori infection and progression of chronic gastritis, significant stepwise cancer risk elevations were seen from CAG-free subjects (H. pylori-positive/CAG-negative) [hazard ratio (HR) 5 8.9, 95% confidence interval (CI) 5 2.7-54.7] to subjects with CAG (H. pylori-positive/CAG-positive) (HR 5 17.7, 95% CI 5 5.4-108.6) and finally to subjects with metaplastic gastritis (H. pylori-negative/CAG-positive) (HR 5 69.7, 95% CI 5 13.6-502.9). In H. pylori-infected CAG-free subjects, significantly elevated cancer risk was observed in the subgroup with active inflammation-based high PG II level or potent immune responsebased high H. pylori antibody titer; the former was associated with a particularly high risk of diffuse-type cancer, and both subgroups showed high cancer incidence rates of around 250/100,000 person-years, comparable to that in subjects with CAG. No such risk elevation was observed in H. pylori-infected subjects with CAG. These results clearly indicate that gastric cancer develops mainly from the gastritis-atrophy-metaplasia-cancer sequence and partly from active inflammation-based direct carcinogenesis, and that serum levels of PG and H. pylori antibody titer provide indices of cancer development in H. pylori-infected subjects.Despite worldwide declines in the incidence of gastric cancer and associated mortality over the past 50 years, this pathology remains one of the leading causes of cancer-related death in Eastern Asia, including Japan, South America and Eastern Europe.1-4 In Japan, more than 100,000 new cases of gastric cancer are diagnosed every year, and the Japanese Ministry of Health, Labor and Welfare reported that 50,136 deaths attributed to the cancer in 2010.5 Gastric cancer thus remains a major health problem in Japan. Development of gastric cancer represents a classical example of host-genetic and environmental interactions and is characterized by a multistep process of molecular and morphological events known as the gastritisatrophy-metaplasia-dysplasia-cancer sequence.6,7 Based on a large number of epidemiological and clinicopathological studies and also on animal experiments using Mongolian gerbils, this sequence, which predominantly leads to intestinal-type cancer, is considered to represent a major route of stomach carcinogenesis, particularly in areas of high cancer risk, such as Japan. Although other environmental and lifestyle factors together wi...

BackgroundEpigenetic alterations accumulate in normal-appearing tissues of patients with cancer, producing an epigenetic field defect. Cross-sectional studies show that the degree of the defect may be associated with risk in some types of cancer, especially cancers associated with chronic inflammation.ObjectiveTo demonstrate, by a multicentre prospective cohort study, that the risk of metachronous gastric cancer after endoscopic resection (ER) can be predicted by assessment of the epigenetic field defect using methylation levels.DesignPatients with early gastric cancer, aged 40–80 years, who planned to have, or had undergone, ER, were enrolled at least 6 months after Helicobacter pylori infection discontinued. Methylation levels of three preselected genes (miR-124a-3, EMX1 and NKX6-1) were measured by quantitative methylation-specific PCR. Patients were followed up annually by endoscopy, and the primary endpoint was defined as detection of a metachronous gastric cancer. Authentic metachronous gastric cancers were defined as cancers excluding those detected within 1 year after the enrolment.ResultsAmong 826 patients enrolled, 782 patients had at least one follow-up, with a median follow-up of 2.97 years. Authentic metachronous gastric cancers developed in 66 patients: 29, 16 and 21 patients at 1–2, 2–3 and ≥3 years after the enrolment, respectively. The highest quartile of the miR-124a-3 methylation level had a significant univariate HR (95% CI) (2.17 (1.07 to 4.41); p=0.032) and a multivariate-adjusted HR (2.30 (1.03 to 5.10); p=0.042) of developing authentic metachronous gastric cancers. Similar trends were seen for EMX1 and NKX6-1.ConclusionsAssessment of the degree of an epigenetic field defect is a promising cancer risk marker that takes account of life history.