渡部 文昭

INTRODUCTION: Spontaneous tumor regression (STR) is a rare phenomenon in which cancer cells partially or completely disappear without treatment. We report a case of intrahepatic cholangiocarcinoma demonstrating STR following endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA). CASE PRESENTATION: A 77-year-old male presented with acute cholecystitis 1 day after percutaneous coronary intervention for acute myocardial infarction. Conservative treatment and endoscopic retrograde gallbladder drainage were performed due to antiplatelet therapy. Cytology of bile juice unexpectedly revealed adenocarcinoma. Further imaging, including CT and mapping biopsy, failed to detect a tumor. Laparoscopic cholecystectomy with gallbladder bed resection showed no histological evidence of malignancy. Four months later, surveillance CT revealed a 15 × 15 mm lesion in segment 3 of the liver. EUS-FNA confirmed adenocarcinoma. Laparoscopic left lateral resection was performed; however, no viable cancer cells were identified, and the lesion was replaced by epithelioid granulomas. Immunohistochemistry demonstrated dense infiltration of CD8-positive cytotoxic T cells, suggesting an immune-mediated regression of the tumor. CONCLUSIONS: This case highlights the possibility of tumor regression in intrahepatic adenocarcinoma following EUS-FNA, potentially triggered by an immune response.

HER2-targeted therapies have improved outcomes in metastatic gastric cancer (mGC), yet assessment of HER2 status in tumor tissues remains limited by heterogeneity and temporal changes. This study aimed to evaluate real-time HER2 expression on circulating tumor cells (CTCs) using the On-chip Sort system. CTCs were enriched from blood samples of 27 mGC patients, identified by cytokeratin staining, and assessed for HER2 expression via fluorescent labeling. The epithelial-mesenchymal transition (EMT) index was calculated based on co-expression of vimentin and cytokeratin. CTCs also underwent whole-genome amplification and targeted sequencing using a cancer gene panel. Patients were stratified into three groups: Group A (n = 13), HER2-positive in tissue; Group B (n = 8), tissue HER2-negative but CTC HER2-positive; and Group C (n = 6), HER2-negative in both tissue and CTCs. All patients received cytotoxic chemotherapy; only Group A received additional HER2-targeted therapy. Group B showed the poorest progression-free survival (PFS: 7.0 months), compared to Group A (15.7 months) and Group C (not reached). CTC HER2 expression correlated with EMT index; Groups A and B also exhibited higher EMT indices and shared EMT-related mutations. These findings suggest that CTC-based HER2 monitoring reflects tumor aggressiveness and may help identify patients who could benefit from HER2-targeted therapy despite negative tissue HER2 status.

BACKGROUND: While seasonality of hospital-acquired infections, including incisional SSI after orthopaedic surgery, is recognized, the seasonality of incisional SSI after general and gastroenterological surgeries remains unclear. STUDY DESIGN: This retrospective single-institute observational study analysed the seasonality and risk factors of incisional SSI after general and gastroenterological surgeries using univariate and multivariable analyses. The evaluated variables included age, sex, surgical approach, surgical urgency, operation time, wound classification, and the American Society of Anesthesiologists physical status (ASA-PS). RESULTS: 8,436 patients were enrolled. General surgeries (n=2,241) showed a pronounced SSI incidence in summer (3.9%; odds ratio [OR] 1.87; 95% confidence interval [CI] 1.05-3.27; p=0.025) compared to other seasons (2.1%). Conversely, gastroenterological surgeries (n=6,195) showed a higher incidence in winter (8.3%; OR 1.38; 95% CI 1.10-1.73; p=0.005) than in other seasons (6.1%). Summer for general surgery (OR 1.90; 95% CI 1.12-3.24; p=0.018) and winter for gastroenterological surgery (OR 1.46; 95% CI 1.17-1.82; p=0.001) emerged as independent risk factors for incisional SSI. Open surgery (OR, 2.72; 95% CI 1.73-4.29, p<0.001) and an ASA-PS score ≥3 (OR, 1.64; 95% CI 1.08-2.50, p=0.021) were independent risk factors for incisional SSI in patients undergoing gastroenterological surgery during winter. CONCLUSION: Seasonality exists in the incisional SSI incidence following general and gastroenterological surgeries. Recognizing these trends may help enhance preventive strategies, highlighting the elevated risk in summer for general surgery and in winter for gastroenterological surgery.

PURPOSE: Mesopancreas resection is a crucial but difficult procedure when performing pancreaticoduodenectomy. This study evaluated the influence of mesopancreas thickness on surgical outcomes in patients undergoing pancreaticoduodenectomy. METHODS: We measured the thickness of the fat tissue on the right side of the superior mesenteric artery from the dorsal margin of the confluence of the superior mesenteric vein and portal vein to the ventral margin of the left renal vein on preoperative contrast-enhanced computed tomography and defined it as the mesopancreas thickness. We evaluated the correlation between mesopancreas thickness and intraoperative and postoperative variables in 357 patients who underwent pancreaticoduodenectomy. RESULTS: Multivariate analysis revealed that a thick mesopancreas was significantly associated with a long operative time (β = 10.361; 95% confidence interval, 0.370-20.353, p = 0.042), high estimated blood loss (β = 36.038; 95% confidence interval, -27.192-99.268, p = 0.013), and a low number of resected lymph nodes (β = -1.551; 95% confidence interval, -2.662--0.439, p = 0.006). This analysis further revealed that thick mesopancreas was a significant risk factor for overall morbidity (odds ratio 2.170; 95% confidence interval 1.340-3.520, p = 0.002), major morbidity (odds ratio 2.430; 95% confidence interval 1.360-4.340, p = 0.003), and a longer hospital stay (β = 2.386; 95% confidence interval 0.299-4.474, p = 0.025). CONCLUSION: A thick mesopancreas could predict a longer operation time, higher estimated blood loss, fewer resected lymph nodes, more frequent overall and major morbidities, and a longer hospital stay in patients who underwent pancreaticoduodenectomy more precisely than the body mass index.

BACKGROUND: The recent guidelines from the European and American Hernia Societies recommend a continuous small-bite suturing technique with slowly absorbable sutures for fascial closure of midline abdominal wall incisions to reduce the incidence of wound complications, especially for incisional hernia. However, this is based on low-certainty evidence. We could not find any recommendations for skin closure. The wound closure technique is an important determinant of the risk of wound complications, and a comprehensive approach to prevent wound complications should be developed. METHODS: We propose a single-institute, prospective, randomized, blinded-endpoint trial to assess the superiority of the combination of continuous suturing of the fascia without peritoneal closure and continuous suturing of the subcuticular tissue (study group) over that of interrupted suturing of the fascia together with the peritoneum and interrupted suturing of the subcuticular tissue (control group) for reducing the incidence of midline abdominal wall incision wound complications after elective gastroenterological surgery with a clean-contaminated wound. Permuted-block randomization with an allocation ratio of 1:1 and blocking will be used. We hypothesize that the study group will show a 50% reduction in the incidence of wound complications. The target number of cases is set at 284. The primary outcome is the incidence of wound complications, including incisional surgical site infection, hemorrhage, seroma, wound dehiscence within 30 days after surgery, and incisional hernia at approximately 1 year after surgery. DISCUSSION: This trial will provide initial evidence on the ideal combination of fascial and skin closure for midline abdominal wall incision to reduce the incidence of overall postoperative wound complications after gastroenterological surgery with a clean-contaminated wound. This trial is expected to generate high-quality evidence that supports the current guidelines for the closure of abdominal wall incisions from the European and American Hernia Societies and to contribute to their next updates. TRIAL REGISTRATION: UMIN-CTR UMIN000048442. Registered on 1 August 2022. https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000055205.