Gastric cancer is the second leading cause of cancer incidence in Japan, although gastric cancer mortality has decreased over the past few decades. This decrease is attributed to a decline in the prevalence of H. pylori infection. Radiographic examination has long been performed as the only method of gastric screening with evidence of reduction in mortality in the past. The revised 2014 Japanese Guidelines for Gastric Cancer Screening approved gastric endoscopy for use in population-based screening, together with radiography. While endoscopic gastric cancer screening has begun, there are some problems associated with its implementation, including endoscopic capacity, equal access, and cost-effectiveness. As H. pylori infection and atrophic gastritis are well-known risk factors for gastric cancer, a different screening method might be considered, depending on its association with the individual’s background and gastric cancer risk. In this review, we summarize the current status and problems of gastric cancer screening in Japan. We also introduce and discuss the results of gastric cancer screening using H. pylori infection status in Hoki-cho, Tottori prefecture. Further, we review risk stratification as a system for improving gastric cancer screening in the future.

The development of image-enhanced endoscopy has dramatically improved the qualitative and quantitative diagnosis of gastrointestinal tumors. In particular, narrow band imaging (NBI) has been widely accepted by endoscopists around the world in their daily practice. In 2009, Yao et al. proposed vessel plus surface (VS) classification, a diagnostic algorithm for early gastric cancer using magnifying endoscopy with NBI (ME-NBI), and in 2016, Muto et al. proposed a magnifying endoscopy simple diagnostic algorithm for early gastric cancer (MESDA-G) based on VS classification. In addition, the usefulness of ME-NBI in the differential diagnosis of gastric cancer from gastritis, diagnosis of lesion extent, inference of histopathological type, and diagnosis of depth has also been investigated. In this paper, we narrative review the basic principles, current status, and future prospects of NBI.

Although antithrombotic agents are widely used for cardiac and cerebrovascular disease prevention, they increase the risk of gastrointestinal (GI) bleeding. To examine GI bleeding risk in association with an esophagogastroduodenoscopy (EGD) biopsy performed in patients without cessation of antithrombotic therapy. This study was prospectively conducted at 14 centers. EGD biopsies were performed in patients receiving antithrombotic agents without cessation, as well as age- and sex-matched controls not receiving antithrombotic therapy. Patients treated with warfarin before the biopsy had a prothrombin time-international normalized ratio level <3.0. The proportion of GI bleeding events was compared between the groups. The patient group (n = 277) underwent a total of 560 biopsies while continuing antithrombotic therapy, of whom 24 were receiving multiple antiplatelet drugs, and 9 were receiving both antiplatelet and anticoagulant agents. The control patients (n = 263) underwent 557 biopsies. The upper-GI bleeding rate within 30 days after the EGD biopsy did not increase in patients without cessation of antithrombotic treatment, regardless of receiving single or multiple antithrombotic agents. We found no significant increase in upper-GI bleeding risk following an EGD biopsy in patients taking antithrombotic agents, suggesting its safety without the need for antithrombotic treatment interruption.

Laser-based photodynamic endoscopic diagnosis (LPDED) is a type of endoscopic diagnosis that uses the fluorescence caused by the photochemical reaction that occurs when a fluorescent substance is irradiated by a light of a specific wavelength. Although 5-aminolevulinic acid (5-ALA) can detect early gastric cancer (EGC) during LPDED, there is an unresolved issue of the differences in fluorescence intensity among histopathological types of gastric cancer. Thus, the aim of the present study was to assess whether protoporphyrinogen oxidase (PPOX), involved in the activation of protoporphyrin IX, can affect the fluorescence intensity in EGC. Thirty-three gastric tumor lesions in 30 patients were assessed by LPDED using a prototype endoscope equipped with a blue laser ray to cause excitation following oral 5-ALA administration. The tumors were then resected by endoscopic submucosal dissection or laparoscopic surgery. PPOX expression was examined immunohistochemically in the excised specimens. To explore the mechanisms of histopathological diversity in PPOX and coproporphyrinogen oxidase (CPOX) expression of EGC, immunohistochemical analysis was performed using 75 surgically resected specimens of diverse EGCs. Among the 33 lesions, 26 tumors were detectable by LPDED, whereas seven were undetectable. Between the LPDED-positive and negative groups, there was a significant difference in histopathology. The expression of PPOX was higher in tubular adenocarcinoma (tub) than in signet-ring cell carcinoma (sig). There were significant differences in PPOX and CPOX expression scores of the surgically resected specimens among tub, poorly differentiated adenocarcinoma (por), and sig. PPOX protein expression could be involved in the fluorescence intensity of LPDED in EGC, possibly reflecting histopathological features.

Background: The indications for endoscopic submucosal dissection (ESD) for gastric cancer are based on preoperative histological assessment; however, examination of tissue biopsy is not always reliable as only a limited portion of the lesion can be obtained. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are markers of inflammatory response and are potentially associated with the grade of malignancy in gastric cancer. We aimed to investigate the association between NLR and PLR and the histology of gastric cancer. Methods: This study included 218 patients who underwent ESD for gastric cancer. The relationship between NLR/PLR and histological diagnosis was investigated. Results: Patients with adenocarcinomas showed significantly higher NLR and PLR than those with adenomas (p < 0.001 and p < 0.05, respectively). Further, patients with undifferentiated adenocarcinoma showed a significantly higher NLR (p < 0.05) than those with differentiated adenocarcinoma. Conclusion: This study suggests that NLR could be a useful marker for assessing early gastric cancer.

Although the recent development and widespread use of image-enhanced endoscopy and magnifying endoscopy have improved endoscopic diagnosis of gastric cancer, it is somewhat complicated, requires a higher level of expertise, and is still subjective. Photodynamic endoscopic diagnosis (PDED) is based on the fluorescence of photosensitizers that accumulate in tumors, which enables objective evaluation independent of the endoscopist’s experience, and is useful for tumor detection. The objective of this work was to perform a narrative review of PDED for gastric tumors and to introduce our approach to PDED in gastric tumors in our hospital. In our review there have been case reports of PDED for gastric cancer, but its usefulness has not been established because no prospective studies evaluating its usefulness have been performed. In our previous study, 85.7% (42/49) of gastric tumors exhibited fluorescence in PDED. PDED may be useful in the diagnosis of early gastric cancer. Our previous studies were pilot studies in cancer patients; therefore, future prospective studies are required to verify the usefulness of PDED.