Publications by authors named "Youichi Kumagai"

Background: Laparoscopic proximal gastrectomy (LPG) is an attractive option for the treatment of early gastric cancer in the upper third of the stomach. No optimal method of reconstruction after LPG has been established because of problems associated with postoperative reflux. Gastric tube reconstruction, a type of esophagogastrostomy, is a simple procedure, but it is associated with a high frequency of reflux esophagitis (RE).

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This review outlines the process of the development of the endocytoscope (EC) with reference to previously reported studies including our own. The EC is an ultra-high-magnification endoscope capable of imaging at the cellular level. The esophagus is the most suitable site for EC observation because it is amenable to vital staining.

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Endocytoscopy (EC) facilitates real-time histological diagnosis of esophageal lesions in vivo. We developed a deep-learning artificial intelligence (AI) system for analysis of EC images and compared its diagnostic ability with that of an expert pathologist and nonexpert endoscopists. Our new AI was based on a vision transformer model (DeiT) and trained using 7983 EC images of the esophagus (2368 malignant and 5615 nonmalignant).

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Objective: We determined the anastomotic site during gastric tube reconstruction in esophagectomy according to the "90-to 60-s rule" using indocyanine green (ICG) fluorescence angiography. We evaluated its safety and efficacy in a prospective multicenter setting.

Methods: We enrolled 129 patients who underwent subtotal esophagectomy for esophageal cancer.

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Background: Gastric tube reconstruction is a form of esophagogastrostomy performed after laparoscopic proximal gastrectomy (LPG). It is a simple and safe technique, but it may cause reflux esophagitis (RE) and impair postsurgical QOL. For several years, we have developed the gastric tube reconstruction and performed it on more than 100 patients.

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The efficacy of pembrolizumab has been demonstrated for all solid tumors showing high frequency microsatellite instability- high(MSI-High). It is a possible treatment option even in cases which do not respond to other forms of chemotherapy. We report a case of a 69-year-old man with MSI-High recurrent colorectal cancer with complete response(CR)after pembrolizumab therapy.

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Duodenal cancer is a leading cause of death after colectomy in patients with familial adenomatous polyposis (FAP). Detailed endoscopic evaluation of duodenal lesions with potential for carcinoma development is therefore mandatory. Here we investigated the features of duodenal lesions in FAP patients using an endocytoscopy system (ECS).

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Gallbladder metastasis from gastric cancer is often found accidentally during postoperative pathological examinations, and its preoperative diagnosis is very difficult. There are a few reports in diagnostic imaging, and it is well known to have a very poor prognosis. There have been 13 reports on gallbladder metastasis from gastric cancer in the Japanese literature.

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Our previous study of duodenal adenoma using an endocytoscopy system (ECS) demonstrated that disappearance of goblet cells and spindle-shaped nuclei with loss of polarity were characteristic features. In addition, round duct openings and finger-like projections were observed in tubular adenoma and villous adenoma, respectively. Here, we retrospectively investigated six cases of histologically proven sporadic non-ampullary mucosal duodenal cancer (NAMDC) using ECS.

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Background: Recently the American Society for Gastrointestinal Endoscopy addressed the 'resect and discard' strategy, determining that accurate differentiation of colorectal polyps (CP) is necessary. Previous studies have suggested a promising application of artificial intelligence (AI), using deep learning in object recognition. Therefore, we aimed to construct an AI system that can accurately detect and classify CP using stored still images during colonoscopy.

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Article Synopsis
  • A study reviewed 13 patients with colonic stenosis caused by non-colorectal extracolonic cancers between July 2012 and January 2018, involving mainly older adults with various types of cancers.
  • *The technical success rate of endoscopic stenting in these non-CRC patients (69%) was significantly lower compared to those with colorectal cancer (98%) and those who were preparing for surgery (99%).
  • *Despite the lower success rates, endoscopic stenting provides a minimally invasive option that can offer quick relief for patients suffering from colonic stenosis due to extracolonic malignancies.
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We experienced a case of low-grade appendiceal mucinous neoplasm complicated by pseudomyxoma peritonei that was successfully treated with cytoreductive surgery and early postoperative intraperitoneal chemotherapy. The patient was a 26- year-old man with massive ascites and a swollen appendix on the computed tomography(CT). The appendix was a cystic mass of 5 cm in size.

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There is no established treatment for appendiceal mucinous adenocarcinoma. When this condition is complicated by pseudomyxoma peritonei(PMP), multidisciplinary treatment is often administered. A 40-year-old woman was diagnosed with right ovarian cancer for which laparotomy was performed.

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Aim: To evaluate the efficacy and safety of third-line chemotherapy (CTx) for patients with unresectable or recurrent gastric cancer (GC) refractory to S-1 with or without platinum and taxanes.

Patients And Methods: We retrospectively analyzed clinicopathological and survival data of 26 patients who underwent third-line CTx.

Results: Irinotecan therapy (odds ratio=0.

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Background: Magnifying endoscopy has demonstrated dramatic morphologic changes in the surface microvasculature of superficial esophageal squamous cell carcinoma (ESCC) according to the depth of invasion. We investigated the mechanism of angiogenesis in early-stage ESCC by examining the expression of vascular endothelial growth factor (VEGF)-A and chondromodulin (ChM)-1.

Methods: Using 41 samples of superficial esophageal cancer (EP and LPM 19 cases, MM or deeper 22 cases) and 7 samples of regenerative squamous epithelium, the expression of VEGF-A and ChM-1 was examined in relation to the histological grade or morphology of the surface microvasculature demonstrated by magnifying endoscopy (types A, B, and C correspond to types A, B1, and B2 and B3 of the magnifying endoscopic classification of the Japan Esophageal Society, respectively).

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The basic treatment for retroperitoneal liposarcoma is surgical therapy. Since the administration of trabectedin for soft tissue sarcoma has been approved, another option for soft tissue sarcoma treatment has been added. We report a case of radical resection after trabectedin therapy for initially unresectable retroperitoneal liposarcoma.

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Background And Aims: The endocytoscopic system (ECS) helps in virtual realization of histology and can aid in confirming histological diagnosis in vivo. We propose replacing biopsy-based histology for esophageal squamous cell carcinoma (ESCC) by using the ECS. We applied deep-learning artificial intelligence (AI) to analyse ECS images of the esophagus to determine whether AI can support endoscopists for the replacement of biopsy-based histology.

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Background/aim: Advances in chemotherapy for gastric cancer have encouraged surgeons to perform conversion surgery following a response to first-line chemotherapy in patients with initially unresectable gastric cancer. In this study we evaluated the efficacy of conversion surgery following first- or second-line chemotherapy for unresectable gastric cancer.

Patients And Methods: We retrospectively analyzed clinicopathological and survival data of 94 patients with unresectable gastric cancer treated with first- (n=94) or second-line (n=43) chemotherapy.

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Background And Aims: Evaluation of endoscopic disease activity for patients with ulcerative colitis (UC) is important when determining the treatment of choice. However, endoscopists require a certain period of training to evaluate the activity of inflammation properly, and interobserver variability exists. Therefore, we constructed a computer-assisted diagnosis (CAD) system using a convolutional neural network (CNN) and evaluated its performance using a large dataset of endoscopic images from patients with UC.

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Background And Aims: The prognosis of esophageal cancer is relatively poor. Patients are usually diagnosed at an advanced stage when it is often too late for effective treatment. Recently, artificial intelligence (AI) using deep learning has made remarkable progress in medicine.

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Background: The relationship between thymidine phosphorylase (TP) and angiogenesis at the early stage of esophageal squamous cell carcinoma has been unclear.

Methods: Using 14 samples of normal squamous epithelium, 11 samples of low-grade intraepithelial neoplasia, and 64 samples of superficial esophageal cancer, microvessel density (MVD) was estimated using immunostaining for CD34 and CD105. TP expression was also evaluated in both cancer cells and stromal monocytic cells (SMCs).

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This retrospective study evaluated an appropriate surgical treatment in patients with perforated gastric cancer. The clinicopathological and survival data on 17 perforated gastric cancer patients treated with surgery were analyzed. The one-stage or two-stage gastrectomy was performed in 8 and 5 patients, respectively.

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Introduction: The characteristics of desmoid tumors(DTs)associated with familial adenomatous polyposis(FAP)and relationships between the development of DTs and the sites of APC germline mutation have not closely been examined Japan.

Patients And Methods: This retrospective study was performed to address these issues by examining patients with FAP who underwent proctocolectomy between 1981 and 2015.

Results: The cumulative 2-year incidence of DT development was 50%.

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We retrospectively investigatedoutcomes in surgically treatedeld erly patients with perforatedcolorectal cancer. The clinicopathological andsurvival data on 54 perforatedcolorectal cancer patients treatedwith surgery were analyzed. They included 12 patients≥75 years old(elderly group)and4 2 patients<75 years old(non-elderly group).

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