廣岡 芳樹

INTRODUCTION: Gastrectomy considerably affects the gut microbiome; however, the association between dysbiosis and post-gastrectomy syndrome remains to be explored. This study prospectively explored fecal gut microbiota alterations before and 3 months after gastrectomy, investigating their potential association with weight loss. METHODS: The gut microbiome of 21 patients with gastric cancer scheduled for gastrectomy in April-October 2022 was analyzed using 16S rRNA gene Next-Generation Sequencing. Their microbiome profiles were compared to those of healthy controls. Bacterial taxa demonstrating significant changes were determined using the Linear Discriminant Analysis Effect Size algorithm and further analyzed for their relationship with weight loss in the gastrectomy cohort. RESULTS: Postoperative complications (≥grade 2) were observed in 14.3% of patients. Postoperative weight loss was －10.9%, with the following breakdown: distal (－7.0%), total (－13.5%), and proximal (－14.0%) gastrectomy (P = 0.003). Microbiota analysis demonstrated a significant incline in the abundance of the Streptococcus salivarius group and a decline in Bacteroides uniformis in patients with gastric cancer compared to healthy controls. The S. salivarius group exhibited a further increase, while B. uniformis showed signs of recovery after gastrectomy. Additionally, 5α-reductase gene levels, reported to decrease as several cancers progress, were found to elevate post-surgery. Furthermore, patients experiencing greater weight loss showed a significant reduction in Faecalibacterium prausnitzii levels, while lower serum prealbumin and zinc levels were associated with the abundance of Escherichia coli. CONCLUSION: Gastrectomy significantly alters the gut microbiome. Supporting microbiome health with prebiotics may help alleviate postoperative issues and improve patients' quality of life.

The new Kyoto guidelines for the management of intraductal papillary mucinous neoplasm (IPMN) provide evidence-based recommendations for the diagnosis and treatment of IPMN. Endoscopic ultrasonography (EUS) is a diagnostic modality with a high spatial resolution that allows detailed observation and obtaining cyst fluid or tissue samples via EUS-guided fine needle aspiration (EUS-FNA). Currently, EUS is an indispensable examination method for the diagnosis of pancreatic diseases. On the other hand, there have been concerns that EUS imaging tends to be highly operator-dependent, and may lack objectivity. Previous guidelines have assigned EUS as an option for patients with worrisome features. However, recent reports indicate that the sensitivity of EUS for the diagnosis of mural nodules (MNs) is more than 90%, comparable or superior to that of contrast-enhanced computed tomography or magnetic resonance cholangiopancreatography. The specific advantages of EUS in the diagnosis of IPMN are: (1) high spatial resolution imaging for the diagnosis of MNs, (2) contrast-enhanced EUS for differentiation of intra-cystic MNs from mucous clots, and (3) pathological diagnosis using EUS-FNA and differential diagnosis of a pancreatic cystic tumor by cystic fluid analysis. In order to utilize EUS in the diagnosis of IPMN, endoscopists are required to have the skills to provide sufficiently objective imaging findings.

PURPOSE: This study aimed to clarify the current treatment status for biliary tract cancers based on data from the National Clinical Database (NCD) in Japan. METHODS: Total 3895 cases of biliary tract cancers registered in the NCD during 2021 were included. We identified the rates of resection, R0 resection, postoperative complications, and incidences of lymph node metastasis for gallbladder carcinoma, perihilar cholangiocarcinoma, distal bile duct carcinoma, and ampullary carcinoma. RESULTS: The number of biliary tract cancers registered in the NCD during 2021 was 3895 (1775 in extrahepatic bile duct carcinoma, 1422 in gallbladder carcinoma, and 698 in ampullary carcinoma). In gallbladder carcinoma, the resection (89.59%) and R0 resection rates (87.99%) were favorable, and the complication rate (6.05%) was lower than that of others. However, the postoperative complication rate could be higher in T3-T4 cases and when extrahepatic bile duct resection was performed concomitantly. Lymph node metastasis was frequently seen in 12.60% at the No. 13a lymph node. In perihilar cholangiocarcinoma, the R0 resection (69.82%) and complication rates (16.75%) were significantly lower and higher, respectively. In distal cholangiocarcinoma and ampullary carcinoma, metastasis was observed in approximately 2% and 10% of the dissected No. 16b1 para-aortic lymph nodes, respectively. In conclusion, although short-term surgical outcomes for biliary tract cancers in Japan might be acceptable, the significantly lower R0 resection and higher complication rates of perihilar cholangiocarcinomas indicate additional challenges for surgeons in the future and should continue to be monitored by the Japanese Society of Hepatobiliary and Pancreatic Surgery.