Germline BRCA2 variant with low variant allele frequency detected in tumor-only comprehensive genomic profiling.

Germline BRCA1/2 variants in comprehensive genomic profiling (CGP) often exhibit variant allele frequency (VAF) exceeding 50%. However, when genomic loss occurs at the ipsilateral allele, including the germline variant in tumor cells, the VAF is low. This case report presents a patient with uterine sarcoma with a pathogenic BRCA2 mutation and low VAF in tumor-only CGP, which was later identified as a germline variant. When genomic alterations in BRCA1/2 are identified in tumor-only CGP, the possible germline origin of the variants should be considered, even if their VAF is very low.

BRCA1/2 reversion mutations in a pan-cancer cohort.

Tumor sensitivity to platinum (Pt)-based chemotherapy and poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors is increased by homologous recombination deficiency-causing mutations; in particular, reversion mutations cause drug resistance by restoring protein function. Treatment response is predicted by breast cancer susceptibility gene 1/2 (BRCA1/2) mutations; however, BRCA1/2 reversion mutations have not been comprehensively studied in pan-cancer cohorts. We aimed to characterize BRCA1/2 reversion mutations in a large pan-cancer cohort of Japanese patients by retrospectively analyzing sequencing data for BRCA1/2 pathogenic/likely pathogenic mutations in 3738 patients with 32 cancer types. We identified somatic mutations in tumors or circulating cell-free DNA that could restore the ORF of adverse alleles, including reversion mutations. We identified 12 (0.32%) patients with somatic BRCA1 (n = 3) and BRCA2 (n = 9) reversion mutations in breast (n = 4), ovarian/fallopian tube/peritoneal (n = 4), pancreatic (n = 2), prostate (n = 1), and gallbladder (n = 1) cancers. We identified 21 reversion events-BRCA1 (n = 3), BRCA2 (n = 18)-including eight pure deletions, one single-nucleotide variant, six multinucleotide variants, and six deletion-insertions. Seven (33.3%) reversion deletions showed a microhomology length greater than 1 bp, suggesting microhomology-mediated end-join repair. Disease course data were obtained for all patients with reversion events: four patients acquired mutations after PARP-inhibitor treatment failure, two showed somatic reversion mutations after disease progression, following Pt-based treatment, five showed mutations after both treatments, one patient with pancreatic cancer and BRCA1 reversion mutations had no history of either treatment. Although reversion mutations commonly occur in BRCA-associated cancers, our findings suggest that reversion mutations due to Pt-chemotherapy might be correlated with BRCA1/2-mediated tumorigenesis even in non-BRCA-associated histologies.

Clinical predominance of whole-exome sequencing to evaluate microsatellite instability status.

The microsatellite instability (MSI)/mismatch repair (MMR) status is one of the critical genomic biomarkers for predicting patient response to immune checkpoint inhibitors (ICIs). In this study, we aimed to investigate the concordance among the MSIsensor score obtained from whole-exome sequencing (WES), which could be a futuristic clinical cancer sequencing method, using only tumor tissues, MSI-PCR results, and immunohistochemistry (IHC) results to analyze various solid cancer types. We first endeavored to set the cut-off value of MSIsensor to determine functional deficient mismatch repair (f-dMMR) status. The MSI status of 1054 patients analyzed using WES was evaluated using MSIsensor. In addition, 87 of these patients were further analyzed using MSI-PCR and MMR IHC to calculate the sensitivity and specificity of the MSIsensor cut-off score. Our results showed that score 12.5 was an adequate cut-off score equivalent to PCR-confirmed MSS/MSI-low and MSI-high statuses, with sensitivity, specificity, and area under the curve values of 95.2%, 100%, and 0.998, respectively. Moreover, we identified false-positive cases of tumors with high mutational burden with an MSIsensor score <12.5, and optional IHC examination could rescue these cases. In conclusion, the MSIsensor score obtained using WES with tumor tissue showed a high clinical validity, with a cut-off value of 12.5 for f-dMMR detection, in combination with optional IHC analysis for MMR. Our novel algorithm will provide insights into the development of ICIs for cancer treatment, particularly when WES becomes a more common cancer genomic test in the near future.

Histological and magnified endoscopic evaluation of villous atrophy in gastrointestinal graft-versus-host disease.

AIM:  To measure histological villous atrophy and to clarify the diagnostic accuracy of endoscopic villous atrophy in gastrointestinal graft-versus-host disease. METHODS:  Data for patients who underwent upper and/or lower endoscopic examinations after hematopoietic stem cell transplantation were retrospectively collected. In study 1, group A included 56 patients in whom GI-GVHD was histologically confirmed and group B included 60 patients in whom GI-GVHD was not histologically confirmed. Group C included 59 patients before HSCT. The lengths of villi and crypts in the duodenum and terminal ileum were histologically measured. In study 2, the diagnostic accuracies of villous atrophy of the duodenum and of the terminal ileum using magnifying endoscopy were evaluated. RESULTS:  In study 1, the lengths of villi and the villi/crypt (V/C) ratios of the duodenum and terminal ileum in group A were significantly smaller than those in the other groups (p < 0.05). V/C ratio was moderately correlated with clinical severity, histological grades, and endoscopic grades in the terminal ileum. In study 2, the diagnostic accuracies of magnified images for villous atrophy were 83.8% in the duodenum and 94.9% in the terminal ileum. CONCLUSION:  Magnifying endoscopy enables evaluation of villous atrophy and is useful for optical biopsy of GVHD.

Clinical impact of the perioperative management of oral anticoagulants in bleeding after colonic endoscopic mucosal resection.

BACKGROUND: Heparin bridging therapy (HBT) is indeed related to a high frequency of bleeding after endoscopic mucosal resection (EMR). In this study, our aim was to investigate clinical impact of management of oral anticoagulants without HBT in bleeding after colonic EMR. METHODS: From data for patients who underwent consecutive colonic EMR, the relationships of patient factors and procedural factors with the risk of bleeding were analysed. Our management of antithrombotic agents was based on the shortest cessation as follows: the administration of warfarin was generally continued within the therapeutic range, and direct oral anticoagulants (DOACs) were not administered on the day of the procedure. We calculated bleeding risks after EMR in patients who used antithrombotic agents and evaluated whether perioperative management of anticoagulants without HBT was beneficial for bleeding. RESULTS: A total of 1734 polyps in 825 EMRs were analysed. Bleeding occurred in 4.0% of the patients and 1.9% of the polyps. The odds ratios for bleeding using multivariate logistic regression analysis were 3.67 in patients who used anticoagulants and 4.95 in patients who used both anticoagulants and antiplatelet agents. In patients with one-day skip of DOACs, bleeding occurred in 6.5% of the polyps, and there were no significant differences in bleeding risk between HBT and continuous warfarin or one-day skip DOACs. CONCLUSIONS: The use of oral anticoagulants was related to bleeding after colonic EMR, and perioperative management of oral anticoagulants based on the shortest cessation without HBT would be clinically acceptable.

Autopsy findings in the early stage of amyotrophic lateral sclerosis with "dropped head" syndrome.

Dropped head syndrome (DHS) has been rarely observed in amyotrophic lateral sclerosis (ALS), and the neuropathological findings of this condition have almost never been described. The identification of transactivation response DNA-binding protein 43 kDa (TDP-43), which binds to RNA/DNA has provided a new method for studying ALS and frontotemporal lobar degeneration (FTLD). Post-mortem examination of an adult sudden death case of a 71-year-old patient who complained of DHS exhibited severe loss of anterior motor neurons in the cervical cord (C4-6). Loss of nerve fibers of the anterior roots was striking compared with posterior roots, together with marked neurogenic atrophy of posterior muscles semispinalis cervicis. Bunina bodies were found in large neurons of Betz giant cells, but not in the motor neurons of spinal cords, or neurons of bulbar regions. Phosphorylated TDP-43 (p-TDP-43)-positive structures were detected in the residual neurons of the cervical, thoracic and lumber cords, hypoglossal nucleus, cerebellar dentate nucleus and parahippocampal cortex, together with ubiquitin-positive inclusions. Phosphorylated Tau positive structures in neuronal cytoplasm were found in the amygdala, entorhinal cortex and parahippocampal cortex, some of which co-expressed p-TDP-43. The medial zone of cervical cords may be the first onset site, and that is the cause of head drop in the early stage of ALS. In spite of detailed examination, the direct cause of sudden death was not verified. This autopsy report revealed the relation of DHS which is a rare clinical manifestation of ALS, and neuropathological findings.

Cecum ulcer is a reliable endoscopic finding in cytomegalovirus colitis concomitant with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Although graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), cytomegalovirus (CMV) reactivation also occurs in patients after allo-HSCT and these conditions often clinically overlap. The aim of this study was to determine reliable endoscopic findings of CMV colitis in patients with gastrointestinal graft-versus-host-disease (GI-GVHD). Patients after allo-HSCT who were histologically confirmed to have GI-GVHD with or without CMV colitis and patients with an immunosuppressive condition were retrospectively analyzed. We divided the patients into three groups: GI-GVHD with CMV colitis (group A), GI-GVHD without CMV colitis (group B), and CMV colitis without undergoing allo-HSCT (group C). From medical records, the involved colorectal areas and endoscopic findings according to the groups were compared. A total of 70 patients were divided into three groups (group A: n = 19, group B: n = 28, group C: n = 23). Mucosal injuries in groups A and C frequently occurred in the cecum including ileocecal valves. On the other hand, there were no abnormal lesions on ileocecal valves in group B. Furthermore, ulcer lesions were more frequently observed in groups A and C than in group B (p < 0.001). The sensitivity and specificity of mucosal injuries in the cecum for prediction of CMV colitis were 89.5 and 76.5%, respectively, and mucosal injuries in the cecum were more reliable findings than CMV antigenemia. Ulcer lesions in the cecum are reliable endoscopic findings for CMV colitis in patients with GI-GVHD after allo-HSCT.

Preventive effect of mesenchymal stem cell culture supernatant on luminal stricture after endoscopic submucosal dissection in the rectum of pigs.

BACKGROUND: Mesenchymal stem cells (MSCs) are valuable in regenerative medicine, and MSC culture supernatant (MSC-CS) reportedly inhibits inflammation and fibrosis. We investigated whether colorectal luminal stricture develops after circumferential endoscopic submucosal dissection (ESD) in the colorectum, and whether the development of luminal stricture could be prevented by using MSC-CS enema. METHODS: In the first experiment, we performed circumferential ESD in the rectums or distal colons of pigs (n = 4 in each group). We sacrificed the pigs on Day 22 and measured the degree of luminal stricture. In the second experiment, we performed circumferential ESD in the rectums of pigs and administered an MSC-CS gel or a control gel enema after ESD for 4 days. We sacrificed the pigs on Day 8 (n = 3 in each group) or 22 (n = 3 in each group) to measure the degree of luminal stricture, and performed histological analysis. RESULTS: Severe luminal stricture was observed in the rectum but not in the distal colon. Moreover, fiber accumulation in the submucosa and hypertrophy of the muscularis propria were observed in the rectum but not in the distal colon. The degree of luminal stricture in the rectum was significantly lower in the MSC-CS group than in the control group. Furthermore, MSC-CS attenuated myofibroblast activation and hypertrophy of the muscularis propria on Day 22, and reduced inflammatory cell infiltration on Day 8. CONCLUSIONS: Luminal stricture after ESD developed only in the rectum because of the difference in myofibroblast activation and fiber accumulation. In addition, MSC-CS enema prevented luminal stricture after ESD, possibly by inhibiting the inflammatory reaction and fibrosis.

Effects of human amnion-derived mesenchymal stromal cell transplantation in rats with radiation proctitis.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) have been reported to be a promising cell source in cell therapy, and large amounts of MSCs can easily be isolated from human amnion. Therapeutic irradiation for intra-pelvic cancer often causes radiation proctitis; however, there is currently no effective treatment. We therefore investigated the effect of transplantation of human amnion-derived MSCs (AMSCs) in rats with radiation proctitis. METHODS: Amnion was obtained at cesarean delivery, and AMSCs were isolated and expanded. Sprague-Dawley rats were γ-irradiated (5 Gy/d) at the rectum for 5 days. On day 5, AMSCs (1 × 10(6) cells) were intravenously transplanted. Rats were killed on day 8. Histological analyses were performed, and messenger RNA expression of inflammatory mediators was measured. In vitro, after γ-irradiation of rat intestinal epithelial cells (IEC-6), the cells were cultured with AMSC-conditioned medium (CM). The effect of AMSC-CM was evaluated by measurement of caspase-3/7 activity, p53 transcription activity and quantitative reverse-transcription-polymerase chain reaction for p53-target genes. RESULTS: Histological examination demonstrated that epithelial injury and infiltration of inflammatory cells in the rectum were significantly suppressed by transplantation of AMSCs. In vitro, the cell injury in IEC-6 cells induced by γ-irradiation was inhibited by AMSC-CM, which also inhibited the upregulation of p53 transcription activity, caspase-3/7 activity and p21 expression. CONCLUSIONS: Transplantation of AMSCs improved radiation proctitis, possibly through inhibition of cell injury and inflammatory reactions. AMSC transplantation should be considered as a new treatment for radiation proctitis.

[Clinical impact of addition of bevacizumab to the first-line chemotherapy regimen in the treatment of patients with metastatic colorectal cancer].

BACKGROUND: Combination regimens containing bevacizumab(BV)are regarded as one of the standard first-line chemotherapy (1stCTx) regimens in the treatment of metastatic colorectal cancer (mCRC). However, some patients cannot be treated with BV because of the short interval from the palliative operation or other reasons. We present a study of some patients who were treated with add-on BV in the middle of the 1stCTx before disease progression(referred to as "midway BV" regimen hereafter), and here, we report the efficacy of the midway BV regimen as observed in our patients. RESULTS: We retrospectively analyzed the data of 74 mCRC patients, who were undergoing 1stCTx treatment at our hospital from January 2010 to September 2012. We divided the patients into 3 groups, depending on when BV was introduced in their regimen: 40, 25, and 9 patients were respectively included in the "no-BV" group (patients who were treated without BV in the 1stCTx), BV group(patients treated with BV from the 1st cycle in the 1stCTx), and the midway-BV group (patients who were initially treated without BV and then received add-on BV). The response rates of patients in the no-BV, BV, and midway-BV groups were 27.5%, 44.0%, and 55.6%, respectively. The median progression-free survival (PFS) and median survival time of patients in the no-BV, BV, and midway-BV groups were, respectively, 9.7 months, 9.3 months, and 12.8 months, and 20.3 months, 22.2 months, and N. R. CONCLUSION: Although few cases were analyzed and there might be many confounding factors, our study suggests that midway BV is potentially useful for patients with metastatic colorectal cancer who are not initially treated with BV in the first cycle of the 1stCTx regimen.

Characterizing multi-PIK3CA mutations across cancer types: Toward precision oncology.

BACKGROUND: PIK3CA mutations are implicated in various cancers, but the implications of multiple concurrent mutations and their orientations within the gene have not been fully explored. METHODS: In this study, we analyzed multi-PIK3CA mutations across a diverse pan-cancer cohort comprising 3564 tumors. RESULTS: Multi-PIK3CA mutations were present in 10.3% of all PIK3CA-mutant tumors, predominantly occurring in breast and gynecological cancers. Notably, mutations within the helical domain (E542:E545) exclusively occurred in the trans-orientation, contrasting with mutations in the kinase ABD and C2 domains, which mainly appeared in the cis orientation. CONCLUSIONS: The distinct pattern of mutation orientations in PIK3CA suggests variable oncogenic potential, with helical domain mutations in the trans-orientation potentially being less oncogenic. These findings highlight the importance of mutation orientation in the PIK3CA gene as potential biomarkers for targeted therapy. This understanding is crucial for designing clinical trials that leverage PI3K inhibitors, aiming for more effective and precise cancer treatment.

Clinical and Diagnostic Utility of Genomic Profiling for Digestive Cancers: Real-World Evidence from Japan.

The usefulness of comprehensive genomic profiling (CGP) in the Japanese healthcare insurance system remains underexplored. Therefore, this large-scale study aimed to determine the usefulness of CGP in diagnosing digestive cancers. Patients with various cancer types recruited between March 2020 and October 2022 underwent the FoundationOne® CDx assay at the Keio PleSSision Group (19 hospitals in Japan). A scoring system was developed to identify potentially actionable genomic alterations of biological significance and actionable genomic alterations. The detection rates for potentially actionable genomic alterations, actionable genomic alterations, and alterations equivalent to companion diagnosis (CDx), as well as the signaling pathways associated with these alterations in each digestive cancer, were analyzed. Among the 1587 patients, 547 had digestive cancer. The detection rates of potentially actionable genomic alterations, actionable genomic alterations, and alterations equivalent to CDx were 99.5%, 62.5%, and 11.5%, respectively. APC, KRAS, and CDKN2A alterations were frequently observed in colorectal, pancreatic, and biliary cancers, respectively. Most digestive cancers, except esophageal cancer, were adenocarcinomas. Thus, the classification flowchart for digestive adenocarcinomas proposed in this study may facilitate precise diagnosis. CGP has clinical and diagnostic utility in digestive cancers.

Infection with male and female Trichuris trichiura diagnosed in a non-endemic area.

Trichuris trichiura parasitizes only humans through fecal-oral transmission. In non-endemic areas, the frequency of endoscopic identification has been increasing due to the increasing number of immigrants from endemic countries. To prevent infection, it is important to pay attention to sanitary conditions such as soil and water sources.

Effects of activation of an alcohol metabolic gene, cigarette smoking, and alcohol intake on the incidence of metachronous gastric cancer in patients who underwent endoscopic resection for gastric cancer: A multicenter retrospective pilot study.

Background and Aim: Metachronous gastric cancer (GC) frequently occurs in patients who have undergone endoscopic resection (ER) for GC. We evaluated the risk for development of metachronous GC following ER for GC based on genetic polymorphisms for alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2), as well as alcohol consumption and smoking habits. Methods: We studied 77 patients who underwent ER for GC (median follow-up of 84 months). Genotyping of ADH1B/ALDH2 was performed using saliva sampling. Histories of alcohol consumption and smoking before and after ER and Helicobacter pylori eradication were documented. Results: Multivariate analyses revealed that homozygous slow-metabolizing ADH1B (hazard ratio [HR] = 2.38, P < 0.13), heavy smoking (HR = 2.36, P < 0.09), and cigarette smoking after ER (HR = 2.47, P < 0.10) were not independently associated with the risk of secondary GC development. We analyzed the cessation status of the 38 patients who were classified as heavy smokers before ER based on their smoking habits after the ER and divided them into a cessation group (n = 27, non-smokers after ER) and a non-cessation group (n = 11). Cumulative incidence curves of secondary GC in the cessation and non-cessation groups revealed 5-year incidence rates of 19.0% and 45.0%, respectively (P = 0.02). Conclusion: Continued cigarette smoking, at a high level, may be an important risk factor for the development of metachronous GC. Advice for smoking cessation should be given.

Experiment on endoscopic balloon dilation for esophageal stenosis after endoscopic submucosal dissection in pigs.

BACKGROUND AND AIM: Endoscopic balloon dilation (EBD) is effective for esophageal stenosis caused by ESD. However, an efficient EBD method has not been established. We, therefore, conducted EBD experiments on porcine esophageal stenosis models. METHODS: Study 1: in dilation models (day 22 after ESD), the thickness of the outer muscle layer (as an index of the extension effect) and the area of muscle fiber bundle necrosis in the inner muscle layer (as an index of thermal damage) were evaluated. Study 2: in restenosis models (day 43 after ESD), the thickness of the fibrous plexus (as an index of restenosis) was evaluated. In total, 12 porcine models were created. RESULTS: Study 1: the thickness of the outer muscle layer was 1243 ± 322 µm in surrounding locations and it was 803 ± 145 µm beneath the laceration (p = 0.005). In cases of muscular layer injury, the area of necrosis was 15,500 ± 10400 µm2 in surrounding locations and it was 40,200 ± 12900 µm2 at the laceration site (p < 0.001). Study 2: the thickness of the fibrous plexus was 1359 ± 196 µm in surrounding locations and it was 1322 ± 136 µm2 in the laceration scar site (p = 0.74). CONCLUSION: Since thermal damage persists until the completion of stenosis, EBD in the initial stage should be carefully performed. An extension effect was observed only at the laceration site and it later returned to a status similar to that of surrounding locations. Additional intervention would be required for preventing restenosis.

Genomic profiling of intestinal/mixed-type superficial non-ampullary duodenal epithelial tumors.

BACKGROUND AND AIM: The mechanism underlying carcinogenesis and the genomic features of superficial non-ampullary duodenal epithelial tumors (SNADETs) have not been elucidated in detail. In this study, we examined the genomic features of incipient SNADETs, such as small lesions resected via endoscopic treatment, using next-generation sequencing (NGS). METHODS: Twenty consecutive patients who underwent endoscopic treatment for SNADETs of less than 20 mm between January and December 2017 were enrolled. Targeted genomic sequencing was performed through NGS using a panel of 160 cancer-related genes. Furthermore, the alteration/mutation frequencies in SNADETs were examined. RESULTS: The maximum size of the SNADETs examined in this study was 12 mm in diameter. Five SNADETs were classified as low-grade dysplasia (LGD) tumors, while 14 SNADETs were classified as high-grade dysplasia tumors. Only one carcinoma in situ was detected. NGS data for 16 samples were obtained. APC alterations were detected in 81% of samples (13/16). KRAS, BRAF, and TP53 alterations were detected in 25% (4/16), 18.8% (3/16), and 6.3% (1/16) of cases, respectively. CONCLUSION: We detected APC alterations in most small SNADETs resected via endoscopic treatment, from LGD to carcinoma samples. Even in SNADETs classified as small LGD exhibited KRAS and BRAF alterations.

Relationships of early esophageal cancer with human papillomavirus and alcohol metabolism.

BACKGROUND: It is well known that an alcohol consumption habit together with inactive heterozygous aldehyde dehydrogenase-2 (ALDH2) is an important risk factor for the development of esophageal squamous cell carcinoma (ESCC). It remains controversial whether human papillomavirus (HPV) infection contributes to the occurrence/development of ESCC. There has been no study in which the relationship between ESCC and HPV in addition to alcohol dehydrogenase-1B (ADH1B) and ALDH2 genotypes was evaluated. AIM: To evaluate relationships between HPV infection and development of esophageal cancer, particularly early esophageal cancer, based on ADH1B/ALDH2 polymorphisms. METHODS: We conducted an exploratory retrospective study using new specimens, and we enrolled 145 patients who underwent endoscopic resection for superficial ESCC and had been observed for more than two years by both physical examination and endoscopic examination in Hokkaido University Hospital. Saliva was collected to analyze genetic polymorphisms of ADH1B/ALDH2. We performed in situ hybridization for resected specimens to detect HPV by using an HPV type 16/18 probe. RESULTS: HPV was detected in 15 (10.3%) of the 145 patients with ESCC. HPV-positive rates in inactive ALDH2*1/*2 and ALDH2*1/*1 + *2/*2 were 10.8% and 9.8%, respectively (P = 1.00). HPV-positive rates in slow-metabolizing ADH1B*1/*1 and ADH1B*1/*2 + *2/*2 were 12.0% and 10.0%, respectively (P = 0.72). HPV-positive rates in the heavy or moderate alcohol consumption group and the light or rare consumption group were 11.1% and 8.7%, respectively (P = 0.68). HPV-positive rates in the heavy smoking group and the light or no smoking group were 11.8% and 8.3%, respectively (P = 0.59). The 3-year incidence rates of secondary ESCC or head and neck cancer after initial treatment in the HPV-positive and HPV-negative groups were 14.4% and 21.4% (P = 0.22), respectively. CONCLUSION: In the present situation, HPV status is considered to be less important than other risk factors, such as alcohol consumption, smoking habit, ADH1B/ALDH2 polymorphisms, and HPV status would therefore have no effect on ESCC risk management.

Cancer gene profiling explores the possible precision medicine for diffuse-type gastric adenocarcinoma.

Diffuse type gastric cancer (DGC), a pathological subtype, is one of the most common malignant solid tumors, and mortality of this tumor is not negligible, especially in early-onset cancer patients. In fact, affirmative personalized treatments based on gene profile have not been established yet. The aim of this study was to provide the possible genotype-matched treatment for DGC through comprehensive examination of genomic variants and analysis of clinicopathological characteristics. We retrospectively studied 23 formalin-fixed, paraffin-embedded samples of patients diagnosed as DGC between January 2003 and December 2015 at the Department of Cancer Pathology, Hokkaido University Graduate School of Medicine. The cases were divided into two groups: early-onset (< 50 years old) and elderly-onset (≥ 50 years old) DGC groups. We performed targeted genomic sequencing using a 163 cancer-related gene panel. The sequencing data were analyzed using an original bioinformatics pipeline called GenomeJack and were clinicopathologically evaluated. Intestinal metaplasia and atrophy were highly observed in the adjacent non-cancerous mucosa in the elderly-onset DGC group compared with those in the early-onset DGC group. The number of somatic variants was significantly higher in the elderly-onset DGC group than in the early-onset DGC group. Fifteen patients (65.2%) harbored at least one genomic alteration of the potential target for genotype-matched treatment. In addition, one patient with hypermutation phenotype was diagnosed as Lynch syndrome due to MLH1 mutation, suggesting the sensitivity for the treatment with immune checkpoint inhibitors. Not only does our study demonstrated the potential utility of the targeted genomic sequencing approach for making informed therapeutic decisions, but it also sheds light on DGC pathogenesis and progression.