The Potential of Narrow-Band Imaging as a Novel Light Source for Photodynamic Therapy for Superficial Cancers via Endoscopes.

Background: Photodynamic therapy (PDT) has advanced through the utilization of photosensitizers and specific-wavelength light (≥ 600 nm). However, the widespread adoption of PDT is still impeded by high equipment costs and stringent laser safety requirements. Porphyrins, crucial in PDT, have another absorbance peak of blue light (λ = 380 - 500 nm). This peak corresponds to the wavelength of narrow-band imaging (NBI) (λ = 390 - 445 nm), an image-enhancement technology integrated into endoscopes by Olympus Medical Systems. The study aimed to investigate the potential of widely adopted NBI as a PDT light source for superficial cancers via endoscopes. Methods: Esophageal and biliary cancers were selected for investigation. Human esophageal cancer cell lines (KYSE30, KYSE70, KYSE170) and cholangiocarcinoma cell lines (HuCCT-1, KKU-213) were subjected to verteporfin-mediated PDT under NBI light (λ = 390 - 445 nm). Assessments included spectrometry, crystal violet staining, and fluorescein imaging of singlet oxygen generation and apoptosis. Results: Verteporfin exhibited a peak (λ = 436 nm) consistent with the NBI spectrum, suggesting compatibility with NBI light. NBI light significantly inhibited the growth of esophageal and biliary cancer cells. The half-maximum effective concentration (EC50) values (5 J/cm2) for KYSE30, KYSE70, KYSE170, HuCCT-1, and KKU-213 were calculated as 2.78 ± 0.37µM, 1.76 ± 1.20 µM, 0.77 ± 0.16 µM, 0.65 ± 0.18 µM, and 0.32 ± 0.04 µM, respectively. Verteporfin accumulation in mitochondria, coupled with singlet oxygen generation and observed apoptotic changes, suggests effective PDT under NBI light. Conclusions: NBI is a promising PDT light source for superficial cancers via endoscopes.

Registered multi-device/staining histology image dataset for domain-agnostic machine learning models.

Variations in color and texture of histopathology images are caused by differences in staining conditions and imaging devices between hospitals. These biases decrease the robustness of machine learning models exposed to out-of-domain data. To address this issue, we introduce a comprehensive histopathology image dataset named PathoLogy Images of Scanners and Mobile phones (PLISM). The dataset consisted of 46 human tissue types stained using 13 hematoxylin and eosin conditions and captured using 13 imaging devices. Precisely aligned image patches from different domains allowed for an accurate evaluation of color and texture properties in each domain. Variation in PLISM was assessed and found to be significantly diverse across various domains, particularly between whole-slide images and smartphones. Furthermore, we assessed the improvement in domain shift using a convolutional neural network pre-trained on PLISM. PLISM is a valuable resource that facilitates the precise evaluation of domain shifts in digital pathology and makes significant contributions towards the development of robust machine learning models that can effectively address challenges of domain shift in histological image analysis.

Fusion Imaging Objectively Demonstrates Improved Pancreas Visualization through Manipulation Techniques: A Prospective Interventional Study.

Objective Abdominal ultrasonography (AUS) is used to screen for abdominal diseases owing to its low cost, safety, and accessibility. However, the detection rate of pancreatic disease using AUS is unsatisfactory. We evaluated the visualization area of the pancreas and the efficacy of manipulation techniques for AUS with fusion imaging. Methods Magnetic resonance imaging (MRI) volume data were obtained from 20 healthy volunteers in supine and right lateral positions. The MRI volume data were transferred to an ultrasound machine equipped with a fusion imaging software program. We evaluated the visualization area of the pancreas before and after postural changes using AUS with fusion imaging and assessed the liquid-filled stomach method using 500 ml of de-aerated water in 10 randomly selected volunteers. Patients This study included 20 healthy volunteers (19 men and 1 woman) with a mean age of 33.0 (21-37.5) years old. Results Fusion imaging revealed that the visualization area of the entire pancreas using AUS was 55%, which significantly improved to 75% with a postural change and 90% when using the liquid-filled stomach method (p=0.043). Gastrointestinal gas is the main obstacle for visualization of the pancreas. Conclusion Fusion imaging objectively demonstrated that manipulation techniques can improve pancreatic visualization.

Partial Stent-in-Stent Method with an Uncovered Self-Expandable Metallic Stent for Unresectable Malignant Hilar Bile Duct Obstruction.

(1) Background: There is controversy regarding stent placement for unresectable malignant hilar biliary obstruction (UMHBO). We mainly use the partial stent-in-stent (PSIS) method with an uncovered self-expandable metallic stent (UCSEMS) based on the drainage area and patency period. In this study, we investigated the usefulness and safety of the PSIS method. (2) Methods: In total, 59 patients who underwent the PSIS method for UMHBO at our hospital were included in the study. The technical success rate, clinical success rate, time to recurrent biliary obstruction (TRBO) and overall survival (OS) from the first placement, factors affecting TRBO and OS, and early complications within 30 days after the procedure were evaluated retrospectively. (3) Results: The technical and clinical success rates were 100% and 96.6%, respectively, with a TRBO of 121 days [95% confidence interval: 82-231] and an OS of 194 days [95% confidence interval: 113-305] after the first placement. Early complications occurred in nine patients (15.3%), including five cases of cholangitis, three cases of pancreatitis, and one case of cholecystitis. (4) Conclusions: The PSIS method for UMHBO is safe and useful with high technical and clinical success rates.

Prognostic Factors for Severe-to-Fatal Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis: A Multicenter Prospective Cohort Study.

The prognostic factors associated with severe-to-fatal post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) remain unclear despite the extensive number of studies on PEP. In total, 3739 ERCP patients with biliary disease with an intact papilla and indicated for ERCP were prospectively enrolled at 36 centers from April 2017 to March 2018. Those with acute pancreatitis diagnosed before ERCP, altered gastrointestinal anatomy, and an American Society of Anesthesiologists (ASA) physical status > 4 were excluded. Univariate and multivariate logistic regression analyses were performed on patient-related factors, operator-related factors, procedure-related factors, and preventive measures to identify potential prognostic factors for severe-to-fatal PEP. Multivariate analyses revealed pancreatic guidewire-assisted biliary cannulation (OR 13.59, 95% CI 4.21-43.83, p < 0.001), post-ERCP non-steroidal anti-inflammatory drug (NSAID) administration (OR 11.54, 95% CI 3.83-34.81, p < 0.001), and previous pancreatitis (OR 6.94, 95% CI 1.45-33.33, p = 0.015) as significant risk factors for severe-to-fatal PEP. Preventive measures included endoscopic biliary sphincterotomy (EST; OR 0.29, 95% CI, 0.11-0.79, p = 0.015) and prophylactic pancreatic stents (PPSs; OR 0.11, 95% CI, 0.01-0.87, p = 0.036). In biliary ERCP, pancreatic guidewire-assisted biliary cannulation, NSAID administration after ERCP, and previous pancreatitis were risk factors for severe-to-fatal PEP, whereas EST and PPS were significant preventive measures for severe-to-fatal PEP.

Safety and Diagnostic Yield of Endoscopic Ultrasound-Guided Fine-Needle Biopsy for Hypervascular Pancreatic Lesions.

Endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) is a common technique for diagnosing pancreatic lesions with high accuracy and a low incidence of procedural adverse events. However, occasional adverse events, particularly bleeding, may occur. Procedures for hypervascular lesions are considered important, but their risks are unknown. We aimed to evaluate the safety and diagnostic yield of EUS-FNB for hypervascular pancreatic solid lesions. This study included 301 patients with 308 solid pancreatic lesions who underwent EUS-FNB between May 2011 and December 2018. We performed propensity-score matching to balance clinical differences between hypervascular and hypovascular lesions and analyzed 52 lesions. We compared the safety and diagnostic performance of propensity score-matched cohorts. The sensitivity, specificity, and accuracy rates of EUS-FNB for hypervascular lesions were 94.7%, 100%, and 96.2%, and those for hypovascular lesions were 80.0%, 100%, and 84.6%, respectively. There was no difference in diagnostic performance between hypervascular and hypovascular lesions. Furthermore, adverse events occurred in only one patient (pancreatitis) in the hypovascular group. There were no significant differences in the occurrence of adverse events between hypervascular and hypovascular lesions (0% vs. 3.8%, p = 1.000). Therefore, EUS-FNB may be safe with a high diagnostic yield, even for hypervascular solid pancreatic lesions.

A Novel Monochromatic Light to Detect Target Specimens Within Endoscopic Ultrasonography-guided Fine-needle Aspiration Biopsy Samples.

BACKGROUND/AIM: Endoscopic ultrasonography (EUS)-guided fine-needle aspiration biopsy (EUS-FNB) enhances the diagnostic capabilities of EUS by providing additional pathological samples. However, detecting the target specimens within the collected samples can be challenging. The aim of this study was to determine the optimal wavelength of light for detection of target specimens within EUS-FNB samples in an animal experiment. MATERIALS AND METHODS: EUS-FNB pancreatic tissue samples were collected from a male beagle (weight, 10 kg), and the samples were illuminated with monochromatic light ranging from 430 to 700 nm in 5-nm intervals. The intensities of the target specimen and blood samples were analyzed using the densitometry of the images obtained through irradiation. RESULTS: We found that transmitted monochromatic light of 605 nm most vividly enhanced the contrast between the target specimens and blood in the samples in the impression of appearance. CONCLUSION: Thus, microscopical observations under transmitted light of 605 nm are optimal for target tissue identification within EUS-FNB samples.

Stomach encyclopedia: Combined single-cell and spatial transcriptomics reveal cell diversity and homeostatic regulation of human stomach.

The stomach is an important digestive organ with various biological functions. However, because of the complexity of its cellular and glandular composition, its precise cellular biology has yet to be elucidated. In this study, we conducted single-cell RNA sequencing (scRNA-seq) and subcellular-level spatial transcriptomics analysis of the human stomach and constructed the largest dataset to date: a stomach encyclopedia. This dataset consists of approximately 380,000 cells from scRNA-seq and the spatial transcriptome, enabling integrated analyses of transcriptional and spatial information of gastric and metaplastic cells. This analysis identified LEFTY1 as an uncharacterized stem cell marker, which was confirmed through lineage tracing analysis. A wide variety of cell-cell interactions between epithelial and stromal cells, including PDGFRA+BMP4+WNT5A+ fibroblasts, was highlighted in the developmental switch of intestinal metaplasia. Our extensive dataset will function as a fundamental resource in investigations of the stomach, including studies of development, aging, and carcinogenesis.

Identification and Quantification of Jaundice by Trans-Conjunctiva Optical Imaging Using a Human Brain-like Algorithm: A Cross-Sectional Study.

Jaundice is caused by excess circulating bilirubin, known as hyperbilirubinemia. This symptom is sometimes caused by a critical hepatobiliary disorder, and is generally identified as yellowish sclera when bilirubin levels increase more than 3 mg/dL. It is difficult to identify jaundice accurately, especially via telemedicine. This study aimed to identify and quantify jaundice by trans-conjunctiva optical imaging. Patients with jaundice (total bilirubin ≥3 mg/dL) and normal control subjects (total bilirubin <3 mg/dL) were prospectively enrolled from June 2021 to July 2022. We took bilateral conjunctiva imaging with a built-in camera on a smartphone (1st generation iPhone SE) under normal white light conditions without any restrictions. We processed the images using an Algorithm Based on Human Brain (ABHB) (Zeta Bridge Corporation, Tokyo, Japan) and converted them into a hue degree of Hue Saturation Lightness (HSL) color space. A total of 26 patients with jaundice (9.57 ± 7.11 mg/dL) and 25 control subjects (0.77 ± 0.35 mg/dL) were enrolled in this study. The causes of jaundice among the 18 male and 8 female subjects (median age 61 yrs.) included hepatobiliary cancer (n = 10), chronic hepatitis or cirrhosis (n = 6), pancreatic cancer (n = 4), acute liver failure (n = 2), cholelithiasis or cholangitis (n = 2), acute pancreatitis (n = 1), and Gilbert's syndrome (n = 1). The maximum hue degree (MHD) optimal cutoff to identify jaundice was 40.8 (sensitivity 81% and specificity 80%), and the AUROC was 0.842. The MHD was moderately correlated to total serum bilirubin (TSB) levels (rS = 0.528, p < 0.001). TSB level (≥5 mg/dL) can be estimated by the formula 21.1603 - 0.7371 × 56.3-MHD2. In conclusion, the ABHB-based MHD of conjunctiva imaging identified jaundice using an ordinary smartphone without any specific attachments and deep learning. This novel technology could be a helpful diagnostic tool in telemedicine or self-medication.

Pancreatic Juice Cytology Evaluations Using Synthetic Secretin and Serial Pancreatic Juice Aspiration Cytological Examination for the Diagnosis of Pancreatic Ductal Adenocarcinoma.

Pathological examination by endoscopic ultrasound-fine needle aspiration is not possible in approximately 10% of pancreatic tumor cases. Pancreatic juice cytology (PJC) is considered an alternative diagnostic method. However, its diagnostic capability is insufficient, and PJC has been repeatedly redevised. Serial pancreatic juice aspiration cytological examination (SPACE) and secretin-loaded PJC (S-PJC) have been recently introduced as alternative diagnostic methods. This study aimed to determine the diagnostic capacity and safety of SPACE and S-PJC using a propensity score-matched analysis. The sensitivity, specificity, and accuracy were 75.0%, 100%, and 92.3% for S-PJC, respectively, and 71.4%, 100%, and 92.3% for SPACE, respectively, meaning that there was no significant difference between the groups. Four patients (15.4%) each in the S-PJC and SPACE groups experienced complications, including postendoscopic retrograde cholangiopancreatography, pancreatitis, and cholangitis. Overall, there was no difference in efficacy and safety between the SPACE and S-PJC groups.

Restaining-based annotation for cancer histology segmentation to overcome annotation-related limitations among pathologists.

Numerous cancer histopathology specimens have been collected and digitized over the past few decades. A comprehensive evaluation of the distribution of various cells in tumor tissue sections can provide valuable information for understanding cancer. Deep learning is suitable for achieving these goals; however, the collection of extensive, unbiased training data is hindered, thus limiting the production of accurate segmentation models. This study presents SegPath-the largest annotation dataset (>10 times larger than publicly available annotations)-for the segmentation of hematoxylin and eosin (H&E)-stained sections for eight major cell types in cancer tissue. The SegPath generating pipeline used H&E-stained sections that were destained and subsequently immunofluorescence-stained with carefully selected antibodies. We found that SegPath is comparable with, or outperforms, pathologist annotations. Moreover, annotations by pathologists are biased toward typical morphologies. However, the model trained on SegPath can overcome this limitation. Our results provide foundational datasets for machine-learning research in histopathology.

Comparison between Target Sample Check Illuminator and White Light Observation in Discriminating the Presence of Target Specimen for Endoscopic Ultrasound-Guided Fine Needle Aspiration Sample.

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an essential endoscopic tissue sampling method for diagnosing pancreatobiliary diseases; however, determining the presence of target specimens mixed in the blood by conventional observation is challenging due to the small size of the obtained sample. This study investigated the usefulness of a target sample check illuminator (TSCI) that emits a specific wavelength of light to determine the presence of target specimens. Twenty-seven patients who underwent EUS-FNA at our hospital were included. Conventional white light observation was performed for the collected samples, followed by TSCI; six people evaluated the presence of the target specimen on a 5-point scale. The target specimen discrimination score using TSCI (median: 5) was significantly higher than that using conventional white light observation (median: 1) (p < 0.001). No significant difference was observed in the discrimination score between the evaluator (novice vs. expert, p = 0.162) and puncture needle (22G vs. 25G, p = 0.196). The discriminability of TSCI in the samples obtained using EUS-FNA was significantly higher than that of conventional observation. TSCI does not depend on the evaluator or puncture needle for the identification of the target specimen; hence, it can provide a good pathological specimen and may contribute to the improvement of the diagnostic ability.

The Characteristics and Prognosis of Alpha-Fetoprotein and Des-Gamma-Carboxy Prothrombin Double-Negative Hepatocellular Carcinoma at Baseline in Higher BCLC Stages.

Alpha-fetoprotein (AFP) and des-gamma-carboxyprothrombin (DCP) are widely used as tumor markers to diagnose hepatocellular carcinoma (HCC). Some advanced HCCs demonstrate neither AFP nor DCP. This study investigated the characteristics and prognosis of AFP (<20 ng/mL) and DCP (<40 mAU/ml) double-negative HCC (DNHC) in higher-stage HCC. Between April 2012 and March 2022, 419 consecutive patients were enrolled with newly diagnosed HCC and 372 patients were selected that were diagnosed by histopathology and/or imaging. AFP-negative, DCP-negative, and double-negative HCC were identified in 262 patients (70.4%), 143 patients (38.2%), and 120 patients (32.3%), respectively. In higher-BCLC stages (BCLC-B, C, and D), 17 patients (14.7%) were DNHC. Although there was no difference in BCLC staging, there were more cases under TNM Stage III in DNHC (71.0% vs. 41.4%, p = 0.026). The median maximum tumor diameter was smaller in DNHC [3.2 (1.8−5.0) vs. 5.5 (3.5−9.0) cm, p = 0.001] and their median survival time was significantly better, even in higher-stage HCC [47.0 (24.0−84.0) vs. 19.0 (14.0−30.0) months, p = 0.027). DNHC in higher-BCLC stage HCC is independent of BCLC staging, characterized by a tumor diameter < 5 cm, and is treatable with a good prognosis.

Does endoscopic sphincterotomy contribute to the prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis after endoscopic biliary stenting for malignant biliary obstruction? A multicenter prospective cohort study.

BACKGROUND: There is no consensus on the necessity of endoscopic sphincterotomy (ES) to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) after endoscopic stenting in patients with malignant biliary obstruction. We investigated the incidence of PEP after endoscopic biliary stenting for malignant biliary obstruction with or without ES in a multicenter prospective cohort study. METHODS: We enrolled 807 patients who underwent endoscopic biliary stenting for malignant biliary obstruction with a native papilla at 36 hospitals between April 2017 and March 2018. The incidence of PEP in patients with or without ES was compared for subgroups based on stent type, placement method, and patient background. Univariate and multivariate analysis was performed to investigate the incidence of PEP in all stenting patients. RESULTS: Plastic and metal stents (MS) were inserted in 598 and 209 patients, respectively. The incidence of PEP in patients with or without ES was 7.9% and 7.4%, respectively among all stenting patients. The incidences of PEP with or without ES in plastic stent insertion patients, patients with MS insertion, stent insertions across the papilla, stent insertions across the papilla in patients without main pancreatic duct obstruction, and fully covered MS insertions across the papilla were compared. There was no overall significant difference in the incidence of PEP between those with or without ES. Multivariate logistic regression analysis for the incidence of PEP in all stenting patients revealed obstruction of the main pancreatic duct at the pancreatic head and epinephrine spraying on the papilla were significant factors; there was no significant difference in the incidence of PEP between patients with or without ES. CONCLUSION: Endoscopic sphincterotomy may not contribute to the prevention of PEP after endoscopic biliary stenting for malignant biliary obstruction, even in cases of insertion with a fully covered MS across the papilla.

Current status and future perspective of linked color imaging for gastric cancer screening: a literature review.

Screening endoscopy has advanced to facilitate improvements in the detection and prognosis of gastric cancer. However, most early gastric cancers (EGCs) have subtle morphological or color features that are difficult to detect by white-light imaging (WLI); thus, even well-trained endoscopists can miss EGC when using this conventional endoscopic approach. This review summarizes the current and future status of linked color imaging (LCI), a new image-enhancing endoscopy (IEE) method, for gastric screening. LCI has been shown to produce bright images even at a distant view and provide excellent visibility of gastric cancer due to high color contrast relative to the surrounding tissue. LCI delineates EGC as orange-red and intestinal metaplasia as purple, regardless of a history of Helicobacter pylori (Hp) eradication, and contributes to the detection of superficial EGC. Moreover, LCI assists in the determination of Hp infection status, which is closely related to the risk of developing gastric cancer. Transnasal endoscopy (ultra-thin) using LCI is also useful for identifying gastric neoplastic lesions. Recently, several prospective studies have demonstrated that LCI has a higher detection ratio for gastric cancer than WLI. We believe that LCI should be used in routine upper gastrointestinal endoscopies.

The Usefulness of Peroral Cholangioscopy for Intrahepatic Stones.

Peroral cholangioscopy (POCS) is believed to be effective in treating intrahepatic stones; however, reports on its efficacy are few. We reviewed the results of intrahepatic stones treated with fluoroscopic guidance or POCS. This study included 26 patients who underwent endoscopic treatment for intrahepatic stones at our institution between January 2017 and December 2021. We retrospectively evaluated the procedure time and adverse events in the first session and the rate of complete stone removal. Complete stone removal was achieved in 92% (24/26); POCS was required in 16 of 26 (62%) procedures and the complete stone removal was achieved in 15 of 16 (94%) of these procedures. The POCS group had a significantly longer procedure time than the fluoroscopy group. Cholangitis incidence was high; however, no difference was noted between patients with and without POCS, and all cases were mild and treated conservatively. Endoscopic treatment for intrahepatic stones may lead to an increase in the incidence of cholangitis, requires specialized devices such as a cholangioscope, and should be performed in an established institution by experienced staff. POCS is useful for intrahepatic stones formed upstream of the stenosis and intrahepatic stones piled in the bile duct.

Intracellular glutathione levels affect the outcomes of verteporfin-mediated photodynamic therapy in esophageal cancer cells.

Photodynamic therapy (PDT) induces cancer cell death by generating reactive oxygen species (ROS). In this process, photosensitizers accumulate in cancer cells irradiated by laser light of a specific wavelength, leading to ROS generation. Verteporfin (VP), a second-generation photosensitizer, is used in PDT for age-related macular degeneration. However, the antitumor effects of VP-PDT remain poorly defined. This study investigated the antitumor effects of VP-PDT on esophageal cancer (EC) cell lines in vitro. Two types of EC cell lines, the KYSE30 cell line, derived from highly differentiated esophageal carcinoma, and the KYSE170 cell line, derived from moderately differentiated carcinoma, were used in this study. VP-PDT exerted effective anticancer effects in both cell lines. Our results revealed that the low-density lipoprotein receptor, albumin receptor, and heme carrier protein-1 in VP uptake were not involved in VP uptake. However, cells rich in intracellular glutathione were resistant to VP-PDT. Our study outcomes suggest that lowering intracellular glutathione via a glutathione synthesis inhibitor or sulfasalazine can increase the effectiveness of VP-PDT-mediated anticancer effects.

Functional genomics screening identifies aspartyl-tRNA synthetase as a novel prognostic marker and a therapeutic target for gastric cancers.

Efficient molecular targeting therapies for most gastric cancers (GCs) are currently lacking, despite GC being one of the most frequent and often devastating malignancies worldwide. Thus, identification of novel therapeutic targets for GC is in high demand. Recent advancements of high-throughput nucleic acid synthesis methods combined with next-generation sequencing (NGS) platforms have made it feasible to conduct functional genomics screening using large-scale pooled lentiviral libraries aimed at discovering novel cancer therapeutic targets. In this study, we performed NGS-based functional genomics screening for human GC cell lines using an originally constructed 6,399 shRNA library targeting all 2,096 human metabolism genes. Our screening identified aspartyl-tRNA synthetase (DARS) as a possible candidate for a therapeutic target for GC. In-house tissue microarrays containing 346 cases of GC combined with public datasets showed that patients with high expression levels of DARS protein exhibited more advanced clinicopathologic parameters and a worse prognosis, specifically among diffuse-type GC patients. Both in vitro and in vivo experiments concretely evidenced that DARS inhibition achieved robust growth suppression of GC cells. Moreover, RNA sequencing of GC cell lines under shRNA-mediated DARS knockdown suggested that DARS inhibition exerts its effect through the inactivation of multiple p-ERK pathways. This MAPK-related growth suppression by DARS inhibition would also be applicable to other cancers; thus, it is warranted to investigate the expression and clinical significance of DARS in a wide spectrum of malignancies. Taken together, NGS-based high-throughput pooled lentiviral screening showed DARS as a novel prognostic marker and a promising therapeutic target for GC. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Gastric cancer and genomics: review of literature.

Gastric cancer (GC) is a major health concern in many countries. GC is a heterogeneous disease stratified by histopathological differences. However, these variations are not used to determine GC management. Next-generation sequencing (NGS) technologies have become widely used, and cancer genomic analysis has recently revealed the relationships between various malignant tumors and genomic information. In 2014, studies using whole-exome sequencing (WES) and whole-genome sequencing (WGS) for GC revealed the entire structure of GC genomics. Genomics with NGS has been used to identify new therapeutic targets for GC. Moreover, personalized medicine to provide specific therapy for targets based on multiplex gene panel testing of tumor tissues has become of clinical use. Recently, immune checkpoint inhibitors (ICIs) have been used for GC treatment; however, their response rates are limited. To predict the anti-tumor effects of ICIs for GC and to select patients suitable for ICI treatment, genomics also provides informative data not only of tumors but also of tumor microenvironments, such as tumor-infiltrating lymphocytes. In therapeutic strategies for unresectable or recurrent malignant tumors, the target is not only the primary lesion but also metastatic lesions, and metastatic lesions are often resistant to chemotherapy. Unlike colorectal carcinoma, there is a heterogeneous status of genetic variants between the primary and metastatic lesions in GC. Liquid biopsy analysis is also helpful for predicting the genomic status of both primary and metastatic lesions. Genomics has become an indispensable tool for GC treatment and is expected to be further developed in the future.