A 28-year-old female with a history of treatment for small intestinal polyps and characteristic pigmentation of her lip was clinically diagnosed with Peutz-Jeghers syndrome(PJS). Her sister had the pathogenic variant of STK11 upon genetic testing. A 20-mm polyp was identified in the second part the patient's duodenum on routine gastrointestinal surveillance, and biopsy revealed a well-differentiated adenocarcinoma. Laparoscopic partial duodenectomy with endoscopy was planned. After confirming the location of the tumor and Kocherization using a laparoscope, the polyp was resected via submucosal dissection under direct visualization with a small incision. The polyp was diagnosed as well-differentiated adenocarcinoma in situ and was resected without remnants. PJS is characterized by a high incidence of malignant tumors, and lifelong surveillance for gastrointestinal and extra-gastrointestinal tumors is necessary. The incidence of duodenal cancer is not high among patients with PJS. However, surgery for advanced cancer is highly invasive. It is desirable to detect the tumors at an early stage so that they can be resected via a less invasive treatment method such as endoscopic resection or laparoscopic surgery with an endoscope.

Cronkhite-Canada syndrome(CCS)is a rare non-inherited disease characterized by gastrointestinal polyposis and ectodermal abnormalities. We report a rare case of CCS associated with gastric cancer and gastric outlet obstruction with a review of the literature. A 75-year-old man was admitted because of frequent vomiting and hypoproteinemia. He was diagnosed with CCS due to typical clinical and laboratory findings including alopecia, nail atrophy, hypoproteinemia, and typical gastrointestinal polyposis. Upper endoscopic examination also pointed out a large gastric cancer mainly located in the antrum and the reversible pyloric obstruction caused by the gastric tumor. Biopsy of the tumor revealed tubular adenocarcinoma. Computed tomography demonstrated the dilated duodenum caused by packing of the gastric tumor. 1.5 months after prednisolone therapy, he underwent total gastrectomy with complete resection of the dilated duodenal bulb. Histological examination revealed gastric cancer(pap>tub1)classified into Stage ⅢC. Postoperative course was uneventful and he moved to another hospital. To our knowledge, including the present case, there were 20 reported cases of CCS associated with gastric cancer from Japan(1979-2022). Also, 7 cases of CCS associated with gastric outlet obstruction was reported.

A 55-year-old woman had been admitted to a hospital with abdominal bloating. Retroperitoneal liposarcoma was suspected and diagnosed as not resectable. She was then referred to our hospital with dyspnea and difficulties with movement due to the huge mass. An abdominal CT revealed a large mass originating in the left retroperitoneum. The tumor occupied most of the abdominal cavity, resulting in the displacement of her organs. However, there was no evidence of infiltration of the tumor into the aorta and inferior vena cava. Under a provisional diagnosis of retroperitoneal liposarcoma, a surgical resection was undertaken. The resected specimen had a maximum diameter of 48 cm and weighed 14 kg. Histopathological examination revealed a differentiated liposarcoma. The patient remains alive 6 months after the operation, without recurrence.

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. The diagnosis of esophageal lesions using EC is based on nuclear density and nuclear abnormality, allowing biopsy histology to be omitted. The observation of nuclear abnormality requires a magnification of ×600 or higher using digital technology. Several staining methods have been proposed, but single staining with toluidine blue or methylene blue is most suitable because the contrast at the border of a cancerous area can be easily identified. A three-tier classification of esophageal lesions visualized by EC is proposed: Type 1 (non-cancerous), Type 2 (endocytoscopic borderline), and Type 3 (cancerous). Since characteristic EC images reflecting pathology can be obtained from non-cancerous esophageal lesions, a modified form of classification with four additional characteristic non-cancerous EC features has also been proposed. Recently, deep-learning AI for analysis of esophageal EC images has revealed that its diagnostic accuracy is comparable to that of expert pathologists.

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). The AI evaluated 114 randomly arranged EC pictures (33 ESCC and 81 nonmalignant lesions) from 38 consecutive cases. An expert pathologist and two nonexpert endoscopists also analyzed the same image set according to the modified type classification (adding four EC features of nonmalignant lesions to our previous classification). The area under the curve calculated from the receiver-operating characteristic curve for the AI analysis was 0.92. In per-image analysis, the overall accuracy of the AI, pathologist, and two endoscopists was 91.2%, 91.2%, 85.9%, and 83.3%, respectively. The kappa value between the pathologist and the AI, and between the two endoscopists and the AI showed moderate concordance; that between the pathologist and the two endoscopists showed poor concordance. In per-patient analysis, the overall accuracy of the AI, pathologist, and two endoscopists was 94.7%, 92.1%, 86.8%, and 89.5%, respectively. The modified type classification aided high overall diagnostic accuracy by the pathologist and nonexpert endoscopists. The diagnostic ability of the AI was equal or superior to that of the experienced pathologist. AI is expected to support endoscopists in diagnosing esophageal lesions based on EC images.

The patient is a 73-year-old man who was diagnosed with perianal Paget's disease by skin biopsy. Biopsy from the dentate line did not show any tumor cells. The patient was considered to undergo sphincter-preserving local resection and subsequently underwent the procedure. Histopathological examination of the resected specimen revealed perianal Paget's disease with a positive anorectal margin. The patient was referred to our department due to postoperative anal stenosis. On the 32nd postoperative day, a double barreled sigmoid colostomy was performed. However, considering the inability to adequately check for detect due to anorectal stenosis and the expected unfavorable anorectal function caused by sphincter- preserving re-operation, a robot-assisted abdominoperineal resection(D1)was performed 7 months after the initial surgery. Histopathological examination of the resected specimen revealed no residual tumor cells in the resected specimen. After local excision for perianal Paget's disease, the skin of the buttock becomes scarred due to skin valve formation and skin grafting, making closure of the perineal wound difficult when performing abdominoperineal resection. In robot-assisted surgery, it is relatively easy to remove the anorectal muscles from the abdominal cavity and reach the sciatico-rectal fossa, thus reducing the size of the perineal wound.

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). We investigated the relationship between RE and gastric emptying, along with nutritional parameters. Subjects and Methods: We compared gastric emptying in patients who had undergone curative LPG with gastric tube reconstruction for gastric cancer with that of patients after total gastrectomy (TG), distal gastrectomy (DG) and of healthy volunteers and patients after DG. The LPG group was divided into an RE LPG-RE (+) group and a non-reflux esophagitis (non-RE) an LPG-RE (−) group, and we compared gastric emptying and indices of nutrition, such as body weight and laboratory findings, between those among LPG-RE (+), LPG-RE (−), and TG groups. Results: The time lag between ingestion and peak 13CO2 expiration (T lag) in the healthy volunteer group was significantly shorter in the LPG group longer than those in the healthy volunteer LPG group and TG group. The T lag was significantly shorter in the RE LPG-RE (+) group than in the non-RE LPG-RE (−) group. The percentage change in body weight percentage in the non-RE LPG-RE (−) group was significantly larger than that in the RE LPG-RE (+) group at 12 months after surgery. Both the serum albumin and hemoglobin levels in the non-RE LPG-RE (−) tended to be preserved compared with those in the RE LPG-RE (+) group and TG group. Conclusions: Gastric emptying was accelerated after LPG, and was associated with RE. Our data suggest that RE could be associated with body weight loss after LPG.

Li-Fraumeni syndrome(LFS)is a hereditary cancer disorder caused by germline variant in TP53 and characterized by various malignancies. Multidisciplinary treatment is needed for tumors of LFS, however, radiation therapy is a relative contraindication because of frequent development of secondary malignancy such as sarcoma in the irradiated field. Case 1: A 22- year-old woman who was diagnosed with LFS by genetic test when she developed upper rectal cancer. Her rectal tumor with marked bilateral lateral lymph node dissection was successfully removed by low anterior resection with extensive lateral lymph node dissection. She underwent resection for ovarian metastasis followed by chemotherapy and radiotherapy but subsequently died by the disease 32 months postoperatively. Case 2(elder sister of Case 1): A brain tumor was identified in the left high frontal lobe to the parietal lobe because of consciousness disorder, after the genetic diagnosis of LFS. The brain tumor was successfully resected. Histological examination revealed diffuse astrocytoma(WHO grade Ⅱ). Local recurrence was observed 46 months later, and radiation therapy was performed. Six months have passed since radiation therapy, no exacerbation of local recurrence has been observed.

An 81-year-old female visited a local hospital with complaints of anal pain. A tumor was found on the right side of her anus, and the histopathological diagnosis was a non-epithelial malignant tumor. Therefore, the patient was referred to our hospital. Result of imaging inspection revealed that the tumor had invaded the lower rectum, but had not distantly metastasized. Based on the findings of another biopsy, the patient was diagnosed with a malignant peripheral nerve sheath tumor (MPNST). Robot-assisted abdominoperineal resection(D1)was performed, and the lesion was resected without any pathological remnants. During the postoperative period, the patient developed perineal wound infection. Subsequently, the patient was discharged from the hospital on postoperative day 10. At the 6-month postoperative follow-up, no recurrence was noted. Most MPNSTs occur in the limbs, trunk, and neck. MPNST in the primary gastrointestinal tract or in the vicinity of the gastrointestinal tract is relatively rare, and in principle, combined resection of the intestinal tract is required for surgical treatment. Here, we report a case of MPNST that occurred near the anus and infiltrated to the lower rectum and was completely resected by robot-assisted abdominoperineal resection.

Background Preoperative chemoradiotherapy(CRT)followed by total mesorectal excision(TME)is used for locally advanced rectal cancer, but it can induce postoperative anorectal function. The primary objective of this study is to confirm the efficacy and safety of preoperative CRT and TME without irradiation to the internal and external sphincter muscles. Subjects and methods Patients were eligible for this study if they met the following inclusion criteria: histologically proven rectal cancer, clinical T3T4N0-2 disease, and a distance between anal margin of tumor and the rental line is more than 2 cm. Twelve patients who underwent preoperative CRT and TME between 2013 and 2017 were enrolled. The primary endpoint was completion rate of sphincter-preserving surgery. Results All patients completed preoperative CRT without Grade 3 or higher adverse effect. Sphincter-preserving surgery was performed in all cases. The 5-year disease-free survival rate was 46.7%, and the local recurrence-free survival rate was 75%, and the overall survival rate was 90.9%. Conclusion It is suggested that preoperative CRT and TME without irradiation to the internal and external sphincter muscles is effective and safe therapy for locally advanced rectal cancer.

BACKGROUND The attention on mismatch repair-deficient (dMMR) gastric cancer has increased in this era of anti-PD-1 blockade therapy; however, the prevalence and molecular genetics of patients with dMMR gastric cancer have not been completely investigated. METHODS Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary gastric cancers of 513 consecutive patients. Genetic and/or epigenetic alterations of the MMR genes were also investigated. RESULTS Loss of expression of one or more MMR proteins was observed in 58 patients (11.3%); 54 patients showed loss of MLH1/PMS2, 3 patients showed loss of MLH1/PMS2/MSH6 and 1 patient showed loss of PMS2 alone. Among these 58 patients, 55 showed hypermethylation of the promoter region of MLH1. Genetic testing revealed that the remaining three patients had Lynch syndrome (n = 1) or Lynch-like syndrome (n = 2). A total of 15 patients (25.9% of all patients with dMMR gastric cancer and 2.9% of all patients with gastric cancer), including 11 patients with stage I-III dMMR gastric cancer who had recurrence and 4 patients with stage IV dMMR gastric cancer, are potential candidates for the use of anti-PD-1 blockades. CONCLUSIONS This is the first study to investigate the frequency and molecular genetic mechanisms of dMMR gastric cancer comprehensively, focusing on the benefit of using PD-1 blockades. Our observations will be beneficial in the clinical practice of metastatic gastric cancer.

Background/Aim: DNA mismatch repair (MMR) deficiency has received increasing attention as a biomarker of anti-PD-1 treatments of solid tumors including gastric cancer (GC). However, efficient screening has not been established. Patients and Methods: A total of 513 patients were tested for the expression of MMR proteins by immunohistochemistry to identify MMR deficient GC. Development of a prediction model was attempted using the common clinicopathological features. Results: In total, 11% (57/513) of the patients showed loss of expression of either one or more MMR proteins (MMR protein deficiency; MMR-D). Multivariate analysis demonstrated that age (≥70 years), sex (female), tumor location (lower 1/3), depth invasion (low, T1/T2/T3), and absence of distant metastasis were significantly independent predictive factors of MMR-D GCs. The MMR-D GC probability estimated by the prediction model ranged from 0.4% to 62.2%, and the area under the curve of the receiver operating characteristics curve was 0.82 (95% confidence interval=0.75-0.87). Conclusion: Our prediction model can sufficiently and efficiently identify MMR-D GCs using clinical features.

We investigated changes in estimated glomerular filtration rate(eGFR)in 11 colorectal cancer patients(6 familial adenomatous polyposis, 5 ulcerative colitis)who underwent restorative proctocolectomy with ileal pouch-anal anastomosis(IPAA) and diverting ileostomy(DI), the tolerability and adverse events of adjuvant chemotherapy(ACT)in 4 cases. After IPAA, eGFR decreased significantly(p=0.02)and did not return to the preoperative level even after stoma closure(p<0.01). mFOLFOX6 was selected as the regimen in 4 candidates, and no significant changes in eGFR after ACT were observed. The relative dose intensity of oxaliplatin was 91.7%, and no gastrointestinal adverse events of Grade 3 or higher were observed. Although in a small number of cases, mFOLFOX6 as ACT after IPAA and DI may be feasible.

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. This study aimed to determine whether gastric tube reconstruction can be a feasible choice after LPG in regard to surgical safety and postoperative nutritional status. Methods The subjects consisted of 171 patients who underwent LPG (n = 102) or laparoscopic total gastrectomy (LTG) (n = 69). We compared the two groups in terms of surgical outcomes, incidence rate of RE, and nutritional status including postoperative weight loss and hemoglobin levels. Results There were no significant differences with regard to the surgical duration and blood loss between the two groups. The incidence of RE was not significantly higher with LPG than with LTG (16.7% vs. 10.1%, respectively; P = 0.07). Later than 2 years and 6 months after surgery, the body weight percentage of preoperative body weight in the LPG group was significantly higher than that in the LTG group. Hemoglobin and ferritin levels in the LPG group were significantly higher than those in the LTG group, later than one after surgery. The overall survival rates were similar between the two groups (5-year survival rates: 97.1% vs. 94.2% in the LPG and LTG groups, respectively; P = 0.69). Conclusions Gastric tube reconstruction after LPG is simple and had better outcomes than LTG in terms of postoperative nutritional status.

Esophageal neuroendocrine carcinoma is extremely rare, and its treatment strategy has not been established. We report 2 cases esophageal neuroendocrine carcinoma. Case 1: A 74-year-old man was diagnosed as having esophageal neuroendocrine carcinoma(clinical T3N4M0, Stage Ⅳa). He received 60 Gy of radiation therapy with etoposide(100 mg/m2)plus cisplatin(80 mg/m2). No recurrence has been detected 1 year after treatment. Case 2: A 78-year-old man was diagnosed as esophageal neuroendocrine carcinoma(clinical T3N0M0, Stage Ⅱ). He underwent esophagectomy with 3 field lymph nodes dissection. Adjuvant chemotherapy was administered with irinotecan(60 mg/m2)plus cisplatin(60 mg/m2). After chemotherapy, he survived 1 year without recurrence.

We herein report 3 cases of advanced gastric cancer with multiple liver metastases who was successfully treated with systemic chemotherapy and underwent conversion surgery with liver resection. There were 2 males and 1 female patients with a range 68 to 74 years of age. Two patients received S-1 plus oxaliplatin therapy and 1 received S-1 plus cisplatin therapy. All patients survived after 5-49 months postoperatively.

We retrospectively analyzed clinicopathological and survival data of 8 patients with unresectable gastric cancer who underwent conversion surgery(CS)following second-line chemotherapy from April 2013 to December 2020. There were 7 males and 1 female patients with a median age of 69(64-76)years old. Five patients had 1 unresectable factor, 2 had 2 unresectable factors, and 1 had 3 unresectable factors. All patients achieved R0 resection. The median survival time(MST) of patients with CS following second-line chemotherapy was significantly longer than that without CS(73.4 vs 12.3 months, respectively). The MST of patients with CS following first-line chemotherapy was significantly longer than that without CS (22.9 vs 12.3 months, respectively). This study suggested that CS following first- or second-line chemotherapy may improve survival duration for unresectable gastric cancer.