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ABSTRACT Background and Aim Methods Results Conclusions No prospective studies have verified the incidence of cholecystitis in patients using the covered self‐expandable metallic stent. In this study, we aimed to investigate the incidence of cholecystitis and its risk factors after low axial force covered self‐expandable metallic stent placement for malignant distal biliary obstruction.This multicenter prospective study included patients diagnosed with unresectable distal biliary obstruction between November 2019 and October 2022 who underwent low axial force covered self‐expandable metallic stent placement.The technical success in the 93 analyzed patients was 100% and clinical success was 98.9%. The 70‐mm covered self‐expandable metallic stent was the most used in 53 patients (57.0%), followed by the 80‐mm type in 27 patients (29.0%), 60‐mm type in 12 patients (12.9%), and 50‐mm type in 1 patient (1.1%). Cholecystitis after covered self‐expandable metallic stent placement occurred in six patients (6.5%). The median time to onset was 46 days (range, 16–315 days), with 1 case in the early stage and five cases in the late stage. There was one mild case, one moderate case, and four severe cases. The presence of tumor involvement at the orifice of the cystic duct was identified as an independent risk factor (odds ratio, 17.0; 95% confidence interval, 1.5–195.1; p = 0.023).The presence of tumor involvement at the orifice of the cystic duct was an independent risk factor for the development of cholecystitis after low axial covered self‐expandable metallic stent placement.Trial registration: University Hospital Medical Information Network (UMIN) (http://www.umin.ac.jp, registration number: UMIN 000038209) [ABSTRACT FROM AUTHOR]

Background/Aims: To validate endoscopic ultrasound-guided tissue acquisition (EUS-TA) used in conjunction with stereomicroscopic on-site evaluation (SOSE) as a preoperative diagnostic tool for resectable pancreatic cancer (R-PC) and borderline resectable PC (BR-PC). Methods: Seventy-eight consecutive patients who underwent EUS-TA for suspected R-PC or BR-PC were enrolled. The primary endpoint was the sensitivity of EUS-TA together with SOSE based on the stereomicroscopically visible white core (SVWC) cutoff value. One or two sites were punctured by using a 22-gauge biopsy needle for EUS-TA, based on the SOSE findings. Results: We collected 99 specimens from 56 and 22 patients with R-PC and BR-PC, respectively. Based on the SOSE results, we performed 57 procedures with one puncture. The SVWC cutoff values were met in 73.7% and 73.1% of all specimens and in those obtained during the first puncture, respectively. The final diagnoses were malignant and benign tumors in 76 and two patients, respectively. The overall sensitivity, specificity, and accuracy of EUS-TA for the 78 lesions were 90.8%, 100%, and 91.0%, respectively. The sensitivity for malignant diagnosis based on the SVWC cutoff value were 89.5% and 90.4% for the first puncture and all specimens, respectively. Conclusions: The sensitivity of EUS-TA in conjunction with SOSE for malignancy diagnosis in patients with suspected R-PC or BR-PC was 90.4%. [ABSTRACT FROM AUTHOR]

Recently, artificial intelligence (AI) has been applied to clinical diagnosis. Although AI has already been developed for gastrointestinal (GI) tract endoscopy, few studies have applied AI to endoscopic ultrasound (EUS) images. In this study, we used a computer-assisted diagnosis (CAD) system with deep learning analysis of EUS images (EUS-CAD) and assessed its ability to differentiate GI stromal tumors (GISTs) from other mesenchymal tumors and their risk classification performance. A total of 101 pathologically confirmed cases of subepithelial lesions (SELs) arising from the muscularis propria layer, including 69 GISTs, 17 leiomyomas and 15 schwannomas, were examined. A total of 3283 EUS images were used for training and five-fold-cross-validation, and 827 images were independently tested for diagnosing GISTs. For the risk classification of 69 GISTs, including very-low-, low-, intermediate- and high-risk GISTs, 2,784 EUS images were used for training and three-fold-cross-validation. For the differential diagnostic performance of GIST among all SELs, the accuracy, sensitivity, specificity and area under the receiver operating characteristic (ROC) curve were 80.4%, 82.9%, 75.3% and 0.865, respectively, whereas those for intermediate- and high-risk GISTs were 71.8%, 70.2%, 72.0% and 0.771, respectively. The EUS-CAD system showed a good diagnostic yield in differentiating GISTs from other mesenchymal tumors and successfully demonstrated the GIST risk classification feasibility. This system can determine whether treatment is necessary based on EUS imaging alone without the need for additional invasive examinations. [ABSTRACT FROM AUTHOR]

Background and Aim: Stereomicroscopic on‐site evaluation (SOSE) is a rapid evaluation method for endoscopic ultrasound‐guided tissue acquisition (EUS‐TA) with a high diagnostic sensitivity when the stereomicroscopically visible white core (SVWC) cut‐off value (≥ 11 mm) is met. We prospectively examined the association between SVWCs and the adequacy of tissue specimens, assuming subsequent comprehensive genome profiling (CGP). Methods: This study included 66 consecutive patients with suspected unresectable pancreatic cancer who underwent EUS‐TA. The primary endpoint was the frequency of combined samples with ≥ 20% tumor cell content that met over twice the SVWC (T‐SVWC) cut‐off value, achieved through multiple punctures. The secondary endpoints were the number of punctures, the percentage of SVWC cut‐off values, adverse events, the positive diagnosis rate, and the tissue section area. Results: The median number of EUS‐TA punctures for suspected unresectable pancreatic cancer was 3 (range, 3–4); SVWC and T‐SVWC cut‐off values were obtained in 171/206 specimens and 65/66 patients, respectively. There were no EUS‐TA‐related adverse events. The positive diagnosis rate of EUS‐TA was 95.5%. Among the 63 patients meeting the T‐SVWC cut‐off value in pathological diagnoses, the median tumor cell content was 40% (range, 5–80%), with 57 patients having tumor cell content ≥ 20%. The median tissue section area was 15 (range, 3–40) mm2. Conclusions: When performing EUS‐TA for unresectable pancreatic cancer with the intention of subsequent CGP, obtaining a high tumor cell content (≥ 20%) by assessing the T‐SVWC cut‐off value via SOSE may serve as a novel indicator for on‐site estimation of CGP suitability for EUS‐TA specimens. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Post‐endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is more common in patients with asymptomatic common bile duct stones (CBDSs) and normal anatomy than in those with symptomatic CBDS; however, studies on the effect of surgically altered anatomy are lacking. We aimed to investigate whether asymptomatic CBDS in balloon enteroscopy‐assisted ERCP cases for surgically altered anatomy also has a high incidence of PEP and analyze the risk factors for PEP. Methods: We retrospectively analyzed 108 consecutive patients who underwent initial ERCP for CBDS with surgically altered anatomies and with naive papilla at Kitasato University Hospital from April 2015 to December 2022. Results: Study participants were as follows: 92 (85%) patients with symptomatic CBDS and 16 (15%) patients asymptomatic CBDS. The overall bile duct cannulation success rate was 89.8%, with PEP occurring in 7.4% of patients (symptomatic CBDS: 3.3%, asymptomatic CBDS: 31.3%). PEP incidence was significantly higher for asymptomatic CBDS (p =.0017). Multivariate analysis identified asymptomatic CBDS and precut sphincterotomy as significant risk factors for PEP. Conclusions: Asymptomatic CBDS may be a risk factor for PEP onset in balloon enteroscopy‐assisted ERCP with surgically altered anatomy. Therefore, the procedure should be performed after obtaining sufficient informed consent and adequate preparation. [ABSTRACT FROM AUTHOR]