Low-power pure-cut hot snare polypectomy for colorectal polyps 10-14 mm in size: a multicenter retrospective study

BACKGROUND AND AIM

Hot snare excision using electrocautery is widely used for large colorectal polyps (>10 mm); however, adverse events occur due to deep thermal injury. Colorectal polyps measuring 10-14 mm rarely include invasive cancer. Therefore, less invasive therapeutic options for this size category are demanding. We have developed hot snare polypectomy with low-power pure-cut current (LPPC HSP), which is expected to contribute to less deep thermal damage and lower risk of adverse events. This study aimed to evaluate the efficacy and safety of LPPC HSP for 10-14 mm colorectal polyps, compared with conventional endoscopic mucosal resection (EMR).

METHODS

In this multicenter, retrospective, observational study, clinical outcomes of EMR and LPPC HSP for 10-14 mm nonpedunculated colorectal polyps between January 2021 and March 2022 were compared using propensity score matching.

RESULTS

We identified 203 EMR and 208 LPPC HSP cases. After propensity score matching, the baseline characteristics between the groups were comparable, with 120 pairs. The en bloc and R0 resection rates were not significantly different between EMR and LPPC HSP groups (95.8% vs 97.5%, P = 0.72; 90.0% vs 91.7%, P = 0.82). The rates of delayed bleeding and perforation did not differ between the groups.

CONCLUSIONS

Compared with conventional EMR, LPPC HSP showed a similar resection ability without an increase in adverse events. These results suggest that LPPC HSP is a safe and effective treatment for 10-14 mm nonpedunculated colorectal polyps.

Novel clip closure technique for a large mucosal defect with anchor-pronged clips after duodenal endoscopic submucosal dissection

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Evaluating false-positive detection in a computer-aided detection system for colonoscopy

BACKGROUND AND AIM

Computer-aided detection (CADe) systems can efficiently detect polyps during colonoscopy. However, false-positive (FP) activation is a major limitation of CADe. We aimed to compare the rate and causes of FP using CADe before and after an update designed to reduce FP.

METHODS

We analyzed CADe-assisted colonoscopy videos recorded between July 2022 and October 2022. The number and causes of FPs and excessive time spent by the endoscopist on FP (ET) were compared pre- and post-update using 1:1 propensity score matching.

RESULTS

During the study period, 191 colonoscopy videos (94 and 97 in the pre- and post-update groups, respectively) were recorded. Propensity score matching resulted in 146 videos (73 in each group). The mean number of FPs and median ET per colonoscopy were significantly lower in the post-update group than those in the pre-update group (4.2 ± 3.7 vs 18.1 ± 11.1; P < 0.001 and 0 vs 16 s; P < 0.001, respectively). Mucosal tags, bubbles, and folds had the strongest association with decreased FP post-update (pre-update vs post-update: 4.3 ± 3.6 vs 0.4 ± 0.8, 0.32 ± 0.70 vs 0.04 ± 0.20, and 8.6 ± 6.7 vs 1.6 ± 1.7, respectively). There was no significant decrease in the true positive rate (post-update vs pre-update: 95.0% vs 99.2%; P = 0.09) or the adenoma detection rate (post-update vs pre-update: 52.1% vs 49.3%; P = 0.87).

CONCLUSIONS

The updated CADe can reduce FP without impairing polyp detection. A reduction in FP may help relieve the burden on endoscopists.

Clinical outcomes and learning curve of Tip-in endoscopic mucosal resection for 15-25 mm colorectal neoplasms among non-experts

BACKGROUND AND AIM

Tip-in endoscopic mucosal resection (EMR) has a high en bloc resection rate for large colorectal neoplasms. However, non-experts' performance in Tip-in EMR has not been investigated. We investigated whether Tip-in EMR can be achieved effectively and safely even by non-experts.

METHODS

This retrospective study included consecutive patients who underwent Tip-in EMR for 15-25 mm colorectal nonpedunculated neoplasms at a Japanese tertiary cancer center between January 2014 and December 2020. Baseline characteristics, treatment outcomes, learning curve of non-experts, and risk factors of failing self-achieved en bloc resection were analyzed.

RESULTS

A total of 597 lesions were analyzed (438 by experts and 159 by non-experts). The self-achieved en bloc resection (69.8% vs 88.6%, P < 0.001) and self-achieved R0 resection (58.3% vs 76.5%, P < 0.001) rates were significantly lower in non-experts with <10 cases of experience than in experts, but not in non-experts with >10 cases. Adverse event (P = 0.165) and local recurrence (P = 0.892) rates were not significantly different between experts and non-experts. Risk factors of failing self-achieved en bloc resection were non-polypoid morphology (OR 3.4, 95% CI 1.6-7.3, P = 0.001), lesions with an underlying semilunar fold (OR 3.6, 95% CI 1.6-7.3, P < 0.001), positive non-lifting sign (OR 3.1, 95% CI 1.2-8.0, P = 0.023), and non-experts with an experience of ≤10 cases (OR 3.6, 95% CI 2.1-6.3, P < 0.001).

CONCLUSION

The clinical outcomes of Tip-in EMR for 15-25 mm lesions performed by non-experts were favorable.

Impact of a new dedicated sheath device for tissue sampling of biliary stricture on pathological diagnostic yield: Retrospective study

Background and study aims Endoscopic transpapillary biliary forceps biopsy (TBFB) is a common method for obtaining specimens from biliary lesions. Its diagnostic yield is unsatisfactory; to overcome this disadvantage, a dedicated sheath has been developed. This study aimed to evaluate the outcomes of conventional TBFB and TBFB with a novel sheath device. Patients and methods Consecutive patients who underwent TBFB between January 2020 and December 2021 were retrospectively evaluated. The rate of obtaining adequate samples, failed attempts at forceps insertion into the bile duct, and sensitivity were compared between the two groups. Results Ninety-two patients who underwent 115 endoscopic retrograde cholangiopancreatographies (76 in the conventional group vs. 39 in the dedicated sheath group) were included. The rates of obtaining adequate samples, failed attempts of the forceps into the bile duct, and sensitivity were 72.4% vs. 89.7% ( P = 0.03), 28.3% vs. 0% ( P < 0.01), and 66.7% vs. 88.9% ( P = 0.02), respectively. Conclusions TBFB with the novel sheath device contributed to improved sensitivity for diagnosis of biliary stricture without insertion of forceps outside the bile duct.

A novel low-power pure-cut hot snare polypectomy for 10-14 mm colorectal adenomas: An ex vivo and a clinical prospective feasibility study (SHARP trial)

BACKGROUND AND AIM

Hot snare polypectomy using blend or coagulation current is widely used; however, it causes deeper tissue heat injury, leading to adverse events. We hypothesized that hot polypectomy using low-power pure cut current (PureCut, effect 1 10 W) could reduce deeper tissue heat injury. We conducted animal experiments to evaluate the deeper tissue heat injury and conducted a prospective clinical study to examine its cutting ability.

METHODS

In a porcine rectum, hot polypectomy using Blend current (EndoCut, effect 3 40 W) and low-power pure cut current was performed. The deepest part of heat destruction and thickness of the non-burned submucosal layer were evaluated histologically. Based on the results, we performed low-power pure cut current hot polypectomy for 10-14 mm adenoma. The primary endpoint was complete resection defined as one-piece resection with negative for adenoma in quadrant biopsies from the defect margin.

RESULTS

In experiments, all low-power pure-cut resections were limited within the submucosal layer whereas blend current resections coagulated the muscular layer in 13% (3/23). The remaining submucosal layer was thicker in low-power pure cut current than in blend current resections. In the clinical study, low-power pure-cut hot polypectomy removed all 100 enrolled polyps. For 98 pathologically neoplastic polyps, complete resection was achieved in 84 (85.7%, 95% confidence interval, 77-92%). The lower limit of the 95% confidence interval was not more than 15% below the pre-defined threshold of 86.6%. No severe adverse events occurred.

CONCLUSIONS

A novel low-power pure-cut hot polypectomy may be feasible for adenoma measuring 10-14 mm. (UMIN000037678).

Closing the defect after gastric endoscopic full-thickness resection with a novel closure device

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Risk factors for intraoperative and delayed perforation related with gastric endoscopic submucosal dissection

BACKGROUND AND AIM

Perforation is one of the most important complications of endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Several studies have examined risk factors for intraoperative and delayed perforations, but most were retrospective analyses with small numbers of patients.

METHODS

This study represents a secondary analysis of a Japanese multicenter prospective cohort study. We investigated the factors associated with each type of perforation using 9015 patients with 9975 EGCs undergoing ESD between July 2010 and June 2012.

RESULTS

Intraoperative perforation occurred in 198 patients (2.2%) with 203 lesions (2.0%), necessitating emergency surgery for four lesions (0.04% [2.0%, 4/203]). Delayed perforation occurred in another 37 patients (0.4%) with 42 lesions (0.4%), requiring emergency surgery for 12 lesions (0.12% [28.6%, 12/42]). Factors showing significant independent correlations with intraoperative perforation were upper or middle third of the stomach; remnant stomach or gastric tube; procedure time ≥100 min; tumor size >35 mm; body mass index (BMI) < 18.5 kg/m2; and ≥72 years. Factors showing significant independent correlations with delayed perforation were procedure time ≥60 min; BMI < 18.5 kg/m2; ≥75 years; ulceration; and tumor size >20 mm. Intraoperative perforation occurred most frequently at the greater curvature in the upper third of the stomach (7.9%), whereas delayed perforation occurred most frequently at the greater curvature in the middle third (1.2%).

CONCLUSION

This multicenter prospective cohort study clarified the risk and risk factors of intraoperative and delayed perforation related to ESD for EGCs, providing information to help endoscopists reduce perforation.

Evaluation of the usefulness of plasma 4β-hydroxycholesterol concentration normalized by 4α-hydroxycholesterol for accurate CYP3A phenotyping

Plasma 4β-hydroxycholesterol (OHC) has drawn attention as an endogenous substrate indicating CYP3A activity. Plasma 4β-OHC is produced by hydroxylation by CYP3A4 and CYP3A5 and by cholesterol autoxidation. Plasma 4α-OHC is produced by cholesterol autoxidation and not affected by CYP3A activity. This study aimed to evaluate the usefulness of plasma 4β-OHC concentration minus plasma 4α-OHC concentration (4β-OHC-4α-OHC) compared with plasma 4β-OHC concentration and 4β-OHC/total cholesterol (TC) ratio in cross-sectional evaluation of CYP3A activity. Four hundred sixteen general adults were divided into 191 CYP3A5*1 carriers and 225 non-carriers. Twenty-six patients with chronic kidney disease (CKD) with CYP3A5*1 allele were divided into 14 with CKD stage 3 and 12 with stage 4-5D. Area under the receiver operating characteristic curve (AUC) for the three indices were evaluated for predicting presence or absence of CYP3A5*1 allele in general adults, and for predicting CKD stage 3 or stage 4-5D in patients with CKD. There was no significant difference between AUC of 4β-OHC-4α-OHC and AUC of plasma 4β-OHC concentration in general adults and in patients with CKD. AUC of 4β-OHC-4α-OHC was significantly smaller than that of 4β-OHC/TC ratio in general adults (p = 0.025), but the two indices did not differ in patients with CKD. In conclusion, in the present cross-sectional evaluation of CYP3A activity in general adults and in patients with CKD with CYP3A5*1 allele, the usefulness of 4β-OHC-4α-OHC was not different from plasma 4β-OHC concentration or 4β-OHC/TC ratio. However, because of the limitations in study design and subject selection of this research, these findings require verification in further studies.

Gel immersion endoscopic mucosal resection for early gastric neoplasms: a multicenter case series study

Several cases have been reported that suggest the efficacy of gel immersion endoscopic mucosal resection (GI-EMR) for gastric neoplasms. However, no study has evaluated treatment outcomes of GI-EMR for gastric neoplasms. This study aimed to investigate the efficacy and safety of GI-EMR for early gastric neoplasms. Nine patients (17 lesions) undergoing gastric GI-EMR were included, with a median lesion size of 10 mm (interquartile range [IQR] 5-13 mm). All lesions were protruding or flat elevated. The median procedure time was 3 minutes (IQR 2-5) and en bloc resection was achieved in all cases. Among 15 neoplastic lesions, the R0 resection rate was 86.7% (13/15 lesions). Adverse events included immediate bleeding requiring hemostasis in two cases, which was controlled endoscopically. No delayed bleeding or perforation occurred. In conclusion, GI-EMR may be a safe and effective treatment for early, small gastric neoplasms. However, due to the small sample in the present study, further investigation is required regarding the indication for this technique.

Randomized controlled trial of remimazolam compared with placebo in Japanese patients undergoing upper gastrointestinal endoscopy: Phase III investigator-initiated clinical trial

OBJECTIVES

To assess the effectiveness of remimazolam against normal saline (placebo) as a sedative agent for endoscopy in a multicenter, randomized, double-blind, investigator-initiated phase III controlled trial.

METHODS

We included 48 Japanese patients undergoing upper gastrointestinal endoscopy. For the procedure, an initial remimazolam dose of 3 mg and additional doses of 1 mg were administered, as determined in the phase II clinical study. The primary study end-point was the successful sedation rate during gastrointestinal endoscopy, determined as a Modified Observer's Assessment of Alertness/Sedation score ≤4 before the start of endoscopy, the completion of gastrointestinal endoscopy, and two or fewer additional doses per 6 min.

RESULTS

The successful endoscopy sedation rates were 91.9% and 9.1% in the remimazolam and placebo groups, respectively (P < 0.01). The time from the end of endoscopy to arousal was 0.0 (0.0-0.0) min for both groups. The number of additional doses required to achieve sedation was lower in the remimazolam group than that in the placebo group (P < 0.01).

CONCLUSIONS

Remimazolam demonstrated a significantly higher sedation effect during upper gastrointestinal endoscopy in Japanese patients with safe and fast recovery compared with placebo.

Usefulness of Belimumab in Adult Patients With Systemic Lupus Erythematosus Evaluated Using Single Indexes: A Meta-Analysis and Systematic Review

Background

Belimumab is the first antibody drug approved for systemic lupus erythematosus (SLE), and is a fully human monoclonal antibody that inhibits soluble B lymphocyte stimulator protein. In clinical trials, a composite index was used to assess efficacy of belimumab. However, clinical guidelines on SLE treatment currently use single efficacy indexes.

Objective

The main objective of this study was to perform a meta-analysis to evaluate the efficacy of belimumab utilizing single indexes used in routine clinical practice, rather than the composite efficacy index used in clinical trials during the development phase. As a secondary endpoint, safety was also evaluated.

Methods

Several databases were searched to identify reports published up to December 1, 2021 on randomized controlled trials examining the efficacy of belimumab in adult patients with SLE. From the clinical trial data, efficacy was evaluated using single indexes including the SLE Disease Activity Index (SLEDAI), British Isles Lupus Assessment Group Index, and Physician Global Assessment. Safety was also assessed. Data were synthesized and analyzed using Review Manager 5.4. This study protocol was registered in the UMIN Clinical Trials Registry (Registration number: UMIN000052846).

Results

The search identified 12 reports that met the inclusion criteria. Five reports were included in efficacy evaluation and 9 in safety evaluation. The primary endpoint was SLEDAI. Significantly more belimumab-treated patients achieved a ≥4-point reduction in SLEDAI (relative risk 1.28; 95% confidence interval, 1.16-1.40; P < 0.00001) compared with placebo. Other efficacy endpoints were also improved significantly in the belimumab group. No difference in safety was found between belimumab and placebo.

Conclusions

The present meta-analysis evaluating clinical trial data using various single indexes recommended by clinical guidelines for SLE verifies that addition of belimumab to standard of care is efficacious for moderate-to-severe SLE.

Rapid and simple quantification of belimumab in human plasma using ultra-high performance liquid chromatography with tandem mass spectrometry

OBJECTIVE

Belimumab is a monoclonal antibody against the B-lymphocyte stimulating factor and is approved for the treatment of patients with systemic lupus erythematosus (SLE) not responding adequately to existing therapies. In this study, we established and validated an assay for quantifying belimumab in human plasma.

METHODS

From the peptides generated by trypsin digestion of belimumab, in silico analysis was used to search for unique peptides to determine the surrogate peptides. Samples were trypsin digested, pretreated with solid phase extraction, and analyzed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) to quantify the surrogate peptide in the samples. The assay was validated according to the Food and Drug Administration (FDA) bioanalytical method validation guidance. We used the established assay to quantify plasma belimumab concentrations in two SLE patients treated with belimumab.

RESULTS

Among the unique peptides identified by the in silico analysis, the peptide with the best peak shape when measured by UHPLC-MS/MS was selected as the surrogate peptide. The validation results of this assay met the acceptable criteria recommended by the FDA guidance. The lower limit of quantification (LLOQ) for belimumab was 2 µg/mL. Recovery rates and matrix effects when corrected for internal standards were 91.5-114.3 % and 96.9-108.4 %, respectively. Plasma concentrations of belimumab were measured in 12 samples from two belimumab-treated SLE patients. All concentrations were within the calibration range.

CONCLUSIONS

We have established and validated a method for measuring plasma belimumab concentrations using UHPLC/MS-MS. By measuring plasma belimumab concentrations in more patients, this method is expected to contribute to appropriate use of belimumab.

Relationship of plasma 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid concentration with OATP1B activity in patients with chronic kidney disease

Organic anion-transporting polypeptides (OATP)1B are drug transporters mainly expressed in the sinusoidal membrane. Many studies have suggested that OATP1B activity is affected by genetic factor, the uremic toxin 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), and inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Coproporphyrin-I (CP-I) is spotlighted as a highly accurate endogenous substrate of OATP1B. We previously reported a positive correlation between plasma CMPF and CP-I concentrations in patients with chronic kidney disease (CKD). The present study evaluated the impact of genetic polymorphisms, CMPF, IL-6, TNF-α, and estimated glomerular filtration rate (eGFR) on individual differences in OATP1B activity in patients with CKD. Seventy-three patients with CKD who received kidney transplant at least 3 months earlier were analyzed. Plasma CP-I concentration was higher in OATP1B1*15 carriers than in non-carriers. In all patients, CP-I did not correlate significantly with CMPF, IL-6, TNF-α, or eGFR. However, when the dataset was cut off at CMPF concentration of 8 and 7 μg/mL, 4 μg/mL, 3 μg/mL or 2 μg/mL, CMPF correlated positively with CP-I, and correlation coefficient tended to be higher as plasma CMPF concentration was lower. In conclusion, OATP1B1*15 impacted OATP1B activity in patients with CKD, but IL-6 and TNF-α did not. However, the impact of CMPF on OATP1B activity was limited to low CMPF concentrations, and the effect could be saturated at high concentrations. When prescribing an OATP1B substrate drug for patients with CKD, the OATP1B1*15 carrier status and plasma CMPF concentration may need to be considered to decide the dose regimen.

Sotos syndrome with marked overgrowth in three Japanese patients with heterozygous likely pathogenic NSD1 variants: case reports with review of literature

We report three Japanese patients with Sotos syndrome accompanied by marked overgrowth, i.e., a 2 8/12-year-old boy with a height of 105.2 cm (+4.4 SD) (patient 1), the mother of patient 1 with a height of 180.8 cm (+4.1 SD) (patient 2), and a 12 10/12-year-old girl with a height of 189.4 cm (+6.3 SD) (patient 3). In addition to the marked overgrowth (tall stature), patients 1-3 exhibited Sotos syndrome-compatible macrocephaly and characteristic features, whereas intellectual and developmental disabilities remained at a borderline level in patient 1 and were apparently absent from patients 2 and 3. Thus, whole exome sequencing was performed to confirm the diagnosis, revealing a likely pathogenic c.6356A>G:p.(Asp2119Gly) variant in NSD1 of patients 1 and 2, and a likely pathogenic c.6599dupT:p.(Ser2201Valfs*4) variant in NSD1 of patient 3 (NM_022455.5). The results, in conjunction with the previously reported data in nine patients with marked overgrowth (≥4.0 SD), imply that several patients with Sotos syndrome have extreme tall stature even in adulthood. Thus, it is recommended to examine NSD1 in patients with marked overgrowth as the salient feature.

Potential for expanding indications and curability criteria of endoscopic resection for early gastric cancer in elderly patients: results from a Japanese multicenter prospective cohort study

BACKGROUND AND AIMS

Evidence for endoscopic resection (ER) in elderly patients with early gastric cancer (EGC) is limited. We assessed its clinical outcomes, and explored new indications and curability criteria.

METHODS

We analyzed data from a Japanese multicenter prospective cohort study. Patients aged ≥75 years with EGC treated with ER were included. We classified "eCuraC-2 (corresponding to noncurative ER, defined in the Japanese gastric cancer treatment guidelines)" into "elderly-high (EL-H)" (>10% estimated metastatic risk) and "elderly-low (EL-L)" (≤10%).

RESULTS

In total, 3,371 patients with 3,821 EGCs were included; endoscopic submucosal dissection (ESD) was the prominent treatment choice. Among them, 3,586 lesions met the guidelines' ER indications and 235 did not. The proportions of en bloc and R0 resections and perforations were 98.9%, 94.4%, and 0.8%, respectively, in EGCs within the indications. In EGCs beyond the indications, they were 99.5%, 85.4%, and 5.9%, respectively, for lesions diagnosed as ≤3 cm, and 96.0%, 64.0%, and 18.0% for those >3 cm. Curative ER ("eCuraA/B") and EL-L were observed in 83.6% and 6.2% of lesions within the indications, respectively, and in 44.2% and 16.8% of lesions <3 cm beyond the indications, respectively. The 5-year cumulative gastric cancer death rates following eCuraA/B and EL-H were 0.3% (95% CI, 0.2-0.6) and 3.5% (2.0-5.7), respectively. Following EL-L, the rate was 0.9% (0.2-3.5) even without subsequent treatment.

CONCLUSIONS

Usefulness of ESD for elderly EGC patients was confirmed by their clinical outcomes. Lesions ≤3 cm and EL-L emerged as new ER indication and curability criterion, respectively.

Evaluation of effects of indoxyl sulfate and parathyroid hormone on CYP3A activity considering the influence of CYP3A5 gene polymorphisms

AIMS

Indoxyl sulfate and parathyroid hormone (PTH), which accumulate in chronic kidney disease (CKD), have been reported to reduce cytochrome P450(CYP)3A activity. Homozygotes of the CYP3A5*3 allele have reduced CYP3A5 activity compared to carriers of at least one CYP3A5*1 allele. 4β-Hydroxycholesterol (4β-OHC) has been established as an endogenous substrate reflecting CYP3A activity. 4β-OHC is produced through hydroxylation by CYP3A4 and CYP3A5 and by autoxidation of cholesterol, whereas 4α-hydroxycholesterol (4α-OHC) is produced solely by autoxidation of cholesterol. This study focused on CKD patients and evaluated the effects of plasma indoxyl sulfate and intact-PTH concentrations on plasma 4β-OHC concentration, 4β-OHC/total cholesterol ratio and 4β-OHC-4α-OHC, with consideration of the influence of CYP3A5 polymorphism.

METHODS

Sixty-three CKD patients were analysed and divided into CYP3A5 carrier group (n = 26) and non-carrier group (n = 37).

RESULTS

Plasma indoxyl sulfate significantly correlated inversely with 4β-OHC concentration and with 4β-OHC-4α-OHC in both the CYP3A5*1 carrier group (r = -0.42, P = .034; r = -0.39, P = .050, respectively) and the non-carrier group (r = -0.45, P = .0054; r = -0.39, P = .019, respectively). However, multiple regression analysis did not identify plasma indoxyl sulfate concentration as a significant independent factor associated with any of the CYP3A activity indices. There was no significant correlation between plasma intact-PTH concentration and any of the CYP3A activity indices.

CONCLUSIONS

The present results suggest that plasma indoxyl sulfate and intact-PTH concentrations do not have clinically significant effects on CYP3A activity in patients with CKD.

Tests of Light-Lepton Universality in Angular Asymmetries of B^{0}→D^{*-}ℓν Decays

We present the first comprehensive tests of the universality of the light leptons in the angular distributions of semileptonic B^{0}-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral B is fully reconstructed in ϒ(4S)→BB[over ¯] decays in data corresponding to 189  fb^{-1} integrated luminosity from electron-positron collisions collected with the Belle II detector. We find no significant deviation from the standard model expectations.

Desmin immunostaining is effective for improving interobserver variability in the depth assessment of the submucosal invasion of colorectal cancers

Tumor depth evaluation is essential for pathological tumor staging because it affects clinical management as an independent risk factor for lymph node metastasis in colorectal cancers. However, poor interobserver variability of invasion depth has been reported. This study aimed to clarify the effectiveness of desmin immunostaining in the histological diagnosis of colorectal cancer. Overall, 63 sets of slides of colorectal cancer stained with hematoxylin and eosin (H&E) and desmin were prepared and independently reviewed by four examiners. After reviewing the desmin-stained slides, the interobserver variability of H&E slides alone was significantly improved for all examiners. For the assessment of Tis vs. T1, the sensitivity and accuracy were significantly improved for all examiners by combining H&E and desmin immunostaining. For the diagnosis of T1b vs. Tis or T1a, specificity and accuracy were significantly improved by adding desmin immunostaining. Ancillary desmin staining to assess submucosal invasion in colorectal cancers significantly improved interobserver agreement, led to efficient screening of T1 cancers, and reduced excessive T1b diagnoses. The combination of desmin immunostaining and H&E staining is highly recommended for diagnosing invasive colorectal cancer.

Endoscopic causes and characteristics of missed gastric cancers after endoscopic submucosal dissection

BACKGROUND AND AIMS

Because endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) preserves the entire stomach, missed gastric cancers (MGCs) are often found in the remaining gastric mucosa. However, the endoscopic causes of MGCs remain unclear. Therefore, we aimed to elucidate the endoscopic causes and characteristics of MGCs after ESD.

METHODS

From January 2009 to December 2018, all patients undergoing ESD for initially detected EGC were enrolled. According to a review of EGD images before ESD, we identified the endoscopic causes (perceptual, exposure, sampling errors, and inadequate preparation) and characteristics of MGC in each endoscopic cause.

RESULTS

Of 2208 patients who underwent ESD for initial EGC, 82 patients (3.7%) had 100 MGCs. The breakdown of endoscopic causes of MGCs was as follows: 69 (69%) perceptual errors, 23 (23%) exposure errors, 7 (7%) sampling errors, and 1 (1%) inadequate preparation. Logistic regression analysis showed that the risk factors for perceptual error were male sex (odds ratio [OR], 2.45; 95% confidence interval [CI], 1.16-5.18), isochromatic coloration (OR, 3.17; 95% CI, 1.47-6.84), greater curvature (OR, 2.31; 95% CI, 1.121-4.40), and lesion size ≤12 mm (OR, 1.74; 95% CI, 1.07-2.84). The sites of exposure errors were around the incisura angularis (11 [48%]), posterior wall of the gastric body (6 [26%]), and antrum (5 [21%]).

CONCLUSIONS

We identified MGCs in 4 categories and clarified their characteristics. Quality improvements in EGD observation, with attention to the risks of perceptual and site of exposure errors, can potentially prevent missing EGCs.

Endoscopic Full-thickness Resection for Gastric Submucosal Tumors: A Japanese Multicenter Prospective Study

OBJECTIVES

Early gastric cancer endoscopic resection (ER) is prominent in Japan. However, evidence regarding ER of gastric submucosal tumors (SMT) is limited. This prospective multicenter phase II study investigated the efficacy and safety of endoscopic full-thickness resection (EFTR) for gastric SMT.

METHODS

EFTR indication for gastric SMT was a size 11-30 mm, histologically proven or clinically suspicious (irregular margin, increasing size, or internal heterogeneity) gastrointestinal stromal tumors (GIST), with no ulceration and intraluminal growth type. The primary endpoint was the complete ER (ER0) rate, with a sample size of 42.

RESULTS

We enrolled 46 patients with 46 lesions between September 2020 and May 2023 at seven Japanese institutions. The mean ± SD (range) endoscopic tumor size was 18.8 ± 4.5 (11-28) mm. The tumor resection and defect closure times were 54 ±26 (22-125) min and 33 ± 28 (12-186) min, respectively. A 100 % ER0 was achieved in all 46 patients. The EFTR procedure was accomplished in all patients without surgical intervention. One patient had delayed perforation and was managed endoscopically. GIST accounted for 76% (n=35) of the cases. R0, R1, and RX rates were 33 (77%), 3 (6.5%), and 7 (15%), respectively.

CONCLUSION

EFTR for gastric SMT of 11-30 mm size is efficacious. It warrants further validation in a large-scale cohort study to determine the long-term outcome of this treatment for patients with gastric GIST.

Precise Measurement of the D_{s}^{+} Lifetime at Belle II

We measure the lifetime of the D_{s}^{+} meson using a data sample of 207  fb^{-1} collected by the Belle II experiment running at the SuperKEKB asymmetric-energy e^{+}e^{-} collider. The lifetime is determined by fitting the decay-time distribution of a sample of 116×10^{3} D_{s}^{+}→ϕπ^{+} decays. Our result is τ_{D_{s}^{+}}=(499.5±1.7±0.9)  fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

Comprehensive Analysis of Early-onset Colorectal Cancer: A Review

Early-onset colorectal cancer (CRC), which refers to CRC diagnosed in individuals below the age of 50 years, is a growing health concern that presents unique challenges in diagnosis, treatment, and long-term outcomes. Although approximately 70% of early-onset CRC cases are sporadic, with no apparent family history, approximately 25% have a familial component, and up to 20% may be associated with germline mutations, indicating a higher prevalence compared with the general population. Despite the progress in identifying the environmental, molecular, and genetic risk factors of early-onset CRC, the underlying causes for the global increase in its incidence remain unclear. This comprehensive review aims to provide a thorough analysis of early-onset CRC by examining the trends associated with its incidence, clinical and pathological characteristics, risk factors, molecular and genetic profiles, prognosis and screening strategies. By deepening our understanding of early-onset CRC, significant advances related to improving the outcomes and alleviating the burden of this disease on individuals, families, and healthcare systems can be achieved.

Discordant microsatellite instability findings in two samples from a patient with biliary cancer that responded to pembrolizumab

Microsatellite instability (MSI) is a key marker to predict response to immune checkpoint inhibitors; however, only 1-2% of biliary cancers have this genomic feature. In a patient with hilar biliary cancer, MSI was examined in two cancer specimens (forceps biopsy from the biliary stricture and endoscopic ultrasound-guided fine-needle aspiration biopsy [EUS-FNAB] from the adjacent lymph node). We observed discordant results, as high frequency of MSI was found only in the forceps biopsy. Although the FNAB sample was 10 times larger than that of the forceps biopsy, the tumor concentration was much lower, which is a possible reason for the discordance. Besides, immunohistochemistry of four mismatch-repair (MMR) proteins showed proficient MMR expressions. The tumor became refractory to gemcitabine, cisplatin, and S-1 but responded well to pembrolizumab. Caution is needed for sample selection and for interpretation of the test's results, to avoid missing rare chance for effective molecular target agents.

Local recurrence risk of esophageal squamous cell carcinoma due to intralesional damage during endoscopic submucosal dissection

BACKGROUND AND AIM

It is unclear whether additional treatment should be considered given the recurrence risk after endoscopic submucosal dissection (ESD) for esophageal squamous cell carcinoma (ESCC) when the vertical margin is positive or unclear (VM1/VMX) due to intralesional damage. This study aimed to elucidate the local recurrence risk of ESCC caused by intralesional damage during ESD.

METHODS

Among consecutive patients with pT1a ESCCs initially treated by ESD at our institution between January 2006 and December 2018, ESCCs diagnosed as VM1/VMX were retrospectively reviewed. Exclusion criteria were piecemeal resection and any additional treatment after ESD. Intralesional damage included the following three types: a macroscopic hole inside the lesion, an incision from the lateral margin of the specimen into the lesion, and crushing injury or burn effect into the deepest area of the lesion without an obvious hole. The local recurrence rate after ESD was primarily analyzed.

RESULTS

Of 1174 pT1a ESCCs initially treated using ESD, 22 lesions were histopathologically diagnosed as VM1/VMX due to intralesional damage (1.9%; 95% confidence interval [CI], 1.2-2.8%). At a median follow-up period of 60.0 (interquartile range, 15.0-84.0) months, no local recurrence was observed (0.0%; 95% CI, 0.0-13.3%) among 21 lesions finally evaluated.

CONCLUSIONS

The impact of intralesional damage during ESD for ESCC on local recurrence might be negligible. Follow-up without additional treatment may be acceptable even if intralesional damage occurs and results in VM1/VMX after ESD for pT1a ESCCs.

Optimization of endoscopic ultrasound-guided tissue sample acquisition for commercially available comprehensive genome profiling

BACKGROUND AND AIM

Optimal tumor samples are crucial for successful analysis using commercially available comprehensive genomic profiling (CACGP). However, samples acquired by endoscopic ultrasound-guided tissue acquisition (EUS-TA) are occasionally insufficient, and no consensus on the optimal number of needle passes required for CACGP exists. This study aimed to explore the optimal number of needle passes required for EUS-TA to procure an ideal sample fulfilling the prerequisite criteria of CACGPs.

METHODS

Patients who underwent EUS-TA for solid masses between November 2019 and July 2021 were retrospectively studied. The correlation between the acquisition rate of an ideal sample and the number of needle passes mounted on a microscope slide was evaluated. Additionally, the factors predicting a successful analysis were investigated in patients scheduled for CACGP using EUS-TA-obtained samples during the same period.

RESULTS

EUS-TAs using 22- and 19-gauge (G) needles were performed in 336 and 57 patients, respectively. There was a positive correlation between the acquisition rate and the number of passes using a 22-G needle (38.9%, 45.0%, 83.7%, and 100% for 1, 2, 3, and 4 passes, respectively), while no correlation was found with a 19-G needle (84.2%, 83.3%, and 85.0% for 1, 2, and 3 passes, respectively). The analysis success rate in patients with scheduled CACGP was significantly higher with ideal samples than with suboptimal samples (94.1% vs 55.0%, P < 0.01).

CONCLUSIONS

The optimal estimated number of needle passes was 4 and 1-2 for 22- and 19-G needles, respectively.

Search for a τ^{+}τ^{-} Resonance in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} Events with the Belle II Experiment

We report the first search for a nonstandard-model resonance decaying into τ pairs in e^{+}e^{-}→μ^{+}μ^{-}τ^{+}τ^{-} events in the 3.6-10  GeV/c^{2} mass range. We use a 62.8  fb^{-1} sample of e^{+}e^{-} collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axionlike particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into τ pairs, ranging from 0.7 to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5  GeV/c^{2} and for the axionlike particle model over the entire mass range.

Measurement of CP Violation in B^{0}→K_{S}^{0}π^{0} Decays at Belle II

We report a measurement of the CP-violating parameters C and S in B^{0}→K_{S}^{0}π^{0} decays at Belle II using a sample of 387×10^{6}  BB[over ¯] events recorded in e^{+}e^{-} collisions at a center-of-mass energy corresponding to the ϒ(4S) resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain C=-0.04_{-0.15}^{+0.14}±0.05 and S=0.75_{-0.23}^{+0.20}±0.04, where the first uncertainties are statistical and the second are systematic.

Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B-Meson Decays at Belle II

We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189  fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3  GeV/c to obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.

Curative Management After Endoscopic Resection for Esophageal Squamous Cell Carcinoma Invading Muscularis Mucosa or Shallow Submucosal Layer-Multicenter Real-World Survey in Japan

INTRODUCTION

Curative management after endoscopic resection (ER) for esophageal squamous cell carcinoma (ESCC), which invades the muscularis mucosa (pMM-ESCC) or shallow submucosal layer (pSM1-ESCC), has been controversial.

METHODS

We identified patients with pMM-ESCC and pSM1-ESCC treated by ER. Outcomes were the predictive factors for regional lymph node and distant recurrence, and survival data were based on the depth of invasion, lymphovascular invasion (LVI), and additional treatment immediately after ER.

RESULTS

A total of 992 patients with pMM-ESCC (n = 749) and pSM1-ESCC (n = 243) were registered. According to the multivariate Cox proportional hazards analysis, pSM1-ESCC (hazard ratio = 1.88, 95% confidence interval 1.15-3.07, P = 0.012) and LVI (hazard ratio = 6.92, 95% confidence interval 4.09-11.7, P < 0.0001) were associated with a risk of regional lymph node and distant recurrence. In the median follow-up period of 58.6 months (range 1-233), among patients with risk factors (pMM-ESCC with LVI or pSM1-ESCC), the 5-year overall survival rates, relapse-free survival rates, and cause-specific survival rates of patients with additional treatment were significantly better than those of patients without additional treatment; 85.4% vs 61.5% ( P < 0.0001), 80.5% vs 53.3% ( P < 0.0001), and 98.5% vs 93.1% ( P = 0.004), respectively. There was no difference in survival rate between the chemoradiotherapy and surgery groups.

DISCUSSION

pSM1 and LVI were risk factors for metastasis after ER for ESCC. To improve the survival, additional treatment immediately after ER, such as chemoradiotherapy or surgery, is effective in patients with these risk factors.

Search for the Lepton Flavor Violating Decays B^{+}→K^{+}τ^{±}ℓ^{∓} (ℓ=e, μ) at Belle

We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,μ), using the full data sample of 772×10^{6}  BB[over ¯] pairs recorded by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range. The obtained limits are the world's best results.

Search for an Invisible Z^{'} in a Final State with Two Muons and Missing Energy at Belle II

The L_{μ}-L_{τ} extension of the standard model predicts the existence of a lepton-flavor-universality-violating Z^{'} boson that couples only to the heavier lepton families. We search for such a Z^{'} through its invisible decay in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'}. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58 GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7  fb^{-1}. We find no excess over the expected standard-model background. We set 90%-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from 3×10^{-3} at low Z^{'} masses to 1 at Z^{'} masses of 8  GeV/c^{2}.

Micromechanical analysis for effective thermal and electromagnetic properties of composite materials containing anisotropical and ellipsoidal fillers oriented randomly

In this study, micromechanical modeling will be performed for composite materials containing fillers oriented randomly in the matrix. The purpose of this study is to derive more general and explicit solutions for the effective thermal and electromagnetic properties of such composite materials without restricting the properties and shapes of the fillers. For this purpose, it is assumed that the physical properties of the filler are the same anisotropic properties as orthorhombic materials, and the shape of the fillers is ellipsoidal. This model is analyzed by micromechanics combining the Eshelby's equivalent inclusion method with the self-consistent method or the Mori-Tanaka's theory. Solutions of the effective thermal and electromagnetic properties both for composite materials containing many kinds of fillers with different shapes and physical properties and for polycrystalline materials can be also derived. Using the obtained solutions, the effect of the shape, the anisotropy, and the volume fraction of the filler on the effective thermal conductivity is examined for the carbon filler / polyethylene and the two types of quartz particles (and voids) / polyethylene. As a result, for the carbon filler / polyethylene, it is found that the effective thermal conductivity of the material when the shape of the filler is flat is about 20% higher than that when the shape of the filler is fibrous. Furthermore, when the shape of the carbon filler is flat, the result when the carbon filler is assumed to be isotropic is significantly different from that when the filler is assumed to be anisotropic. From the above, when the filler is oriented randomly in the material, it is found that simultaneously considering not only the shape of the filler but also its anisotropic properties is important to accurately evaluate the effective physical properties of the composite material. For two types of quartz particles (and voids) / polyethylene materials, the experimental result agrees better with the result of the Mori-Tanaka's theory than that of the self-consistent method, even if the volume fraction of the filler is more than 50%. From the above results, it is found that the analytical solutions of this study can generally explain the experimental results and can be applied to actual materials.

Search for Lepton-Flavor-Violating τ Decays to a Lepton and an Invisible Boson at Belle II

We search for lepton-flavor-violating τ^{-}→e^{-}α and τ^{-}→μ^{-}α decays, where α is an invisible spin-0 boson. The search uses electron-positron collisions at 10.58 GeV center-of-mass energy with an integrated luminosity of 62.8  fb^{-1}, produced by the SuperKEKB collider and collected with the Belle II detector. We search for an excess in the lepton-energy spectrum of the known τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ} and τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decays. We report 95% confidence-level upper limits on the branching-fraction ratio B(τ^{-}→e^{-}α)/B(τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ}) in the range (1.1-9.7)×10^{-3} and on B(τ^{-}→μ^{-}α)/B(τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}) in the range (0.7-12.2)×10^{-3} for α masses between 0 and 1.6  GeV/c^{2}. These results provide the most stringent bounds on invisible boson production from τ decays.

First Observation of Λπ^{+} and Λπ^{-} Signals near the K[over ¯]N(I=1) Mass Threshold in Λ_{c}^{+}→Λπ^{+}π^{+}π^{-} Decay

Using the data sample of 980  fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}→Λπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.3±0.6(stat)±0.9(syst)  MeV/c^{2} [1438.5±0.9(stat)±2.5(syst)  MeV/c^{2}], an intrinsic width of 11.5±2.8(stat)±5.3(syst)  MeV/c^{2} [33.0±7.5(stat)±23.6(syst)  MeV/c^{2}] with a significance of 7.5σ (6.2σ). As these two signals are very close to the K[over ¯]N threshold, we also investigate the possibility of a K[over ¯]N cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.

Complete endoscopic removal rate of detected colorectal polyps in a real world out-patient practical setting

OBJECTIVES

Colonoscopy with adenomatous polypectomy reduces the incidence and mortality of colorectal cancer. We introduced a strategy of removing all neoplastic polyps in single-session out-patient colonoscopy using cold polypectomy. We aimed to investigate the achievement of single-session complete removal rate of detected colorectal polyps in clinical practice.

MATERIALS AND METHODS

This retrospective study included colonoscopy-scheduled 40-79-year-old outpatients, with at least one colorectal neoplasm, between January 2015 and December 2016. Exclusion criteria were: colorectal neoplasms 21 mm or larger in size; pre-examination for colorectal surgery or endoscopic submucosal dissection; colonoscopy performed by health check program; ongoing antithrombotic treatment; inflammatory bowel disease; familial adenomatous polyposis. We defined 'clean colon' as the removal of all detected neoplastic polyps in a single-session colonoscopy. We evaluated clean colon rate, factors relating to clean colon failure and complications.

RESULTS

We evaluated 2527 patients (mean age 68 years; 799 women) with 8203 colorectal polyps (7675 adenomas, 423 serrated lesions, 105 Tis and T1 cancers). In 1-4 mm polyps, cold snare polypectomy (CSP; 51.8%) and cold forceps polypectomy (CFP; 45.8%) were applied. Clean colon rates were 95.1% per patient and 97.1% per lesion. The significant factors denoting clean colon failure were inadequate bowel preparation, ≥5 lesions, and the most advanced estimated histology of adenocarcinoma, on multivariate analyses. Post-polypectomy bleeding requiring endoscopic hemostasis occurred in five patients (0.2%) who had undergone endoscopic mucosal resection (EMR) or hot snare polypectomy (HSP). Perforation occurred in one patient (0.04%) with EMR.

CONCLUSIONS

The clean colon rates were satisfactory in single-session out-patient colonoscopy using cold polypectomy.

Efficacy and Safety of Gel Immersion Endoscopic Mucosal Resection for Non-Pedunculated Colorectal Polyps

Underwater endoscopic mucosal resection (UEMR) has become a popular endoscopic resection method for large colorectal neoplasms. However, visualization can be poor during UEMR due to the presence of intestinal fluid. Gel immersion endoscopic mucosal resection (GIEMR), using a specially developed gel (Viscoclear®, Otsuka Pharmaceutical Factory, Tokushima, Japan), can improve the visual field. However, reports of GIEMR for colorectal polyps are limited. Herein, we evaluated the short-term outcomes of GIEMR for non-pedunculated colorectal neoplasms (NPCRN). This single-center, retrospective, and observational study includes 25 lesions in 20 patients with NPCRN who underwent GIEMR between January and October 2022. The short-term outcomes and adverse events were evaluated. The lesion locations were as follows: right colon, 18 lesions; left colon, 7 lesions; and rectum, none. The median tumor diameter was 15 (IQR, 10–18) mm. Histological classification was as follows: sessile serrated lesion, 9 cases; adenoma, 12 cases; and intramucosal adenocarcinoma, 4 cases. The overall en bloc resection rates and R0 resection rates were 80% (20/25) and 72% (18/25). For NPCRN in 10–19 mm, the en bloc resection rate was 75% (12/16), with an R0 resection rate of 69% (11/16). No post-polypectomy bleeding, perforation, or post-coagulation syndrome were observed. The findings of our study provide preliminary evidence of the efficacy and safety of GIEMR for NPCRN. Therefore, GIEMR may be a promising novel endoscopic resection method for NPCRN.

Observation of e^{+}e^{-}→ωχ_{bJ}(1P) and Search for X_{b}→ωϒ(1S) at sqrt[s] near 10.75 GeV

We study the processes e^{+}e^{-}→ωχ_{bJ}(1P) (J=0, 1, or 2) using samples at center-of-mass energies sqrt[s]=10.701, 10.745, and 10.805 GeV, corresponding to 1.6, 9.8, and 4.7  fb^{-1} of integrated luminosity, respectively. These data were collected with the Belle II detector during special operations of the SuperKEKB collider above the ϒ(4S) resonance. We report the first observation of ωχ_{bJ}(1P) signals at sqrt[s]=10.745  GeV. By combining Belle II data with Belle results at sqrt[s]=10.867  GeV, we find energy dependencies of the Born cross sections for e^{+}e^{-}→ωχ_{b1,b2}(1P) to be consistent with the shape of the ϒ(10753) state. These data indicate that the internal structures of the ϒ(10753) and ϒ(10860) states may differ. Including data at sqrt[s]=10.653  GeV, we also search for the bottomonium equivalent of the X(3872) state decaying into ωϒ(1S). No significant signal is observed for masses between 10.45 and 10.65  GeV/c^{2}.

Measurement of the Λ_{c}^{+} Lifetime

An absolute measurement of the Λ_{c}^{+} lifetime is reported using Λ_{c}^{+}→pK^{-}π^{+} decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the ϒ(4S) resonance, is 207.2  fb^{-1}. The result, τ(Λ_{c}^{+})=203.20±0.89±0.77  fs, where the first uncertainty is statistical and the second systematic, is the most precise measurement to date and is consistent with previous determinations.

Search for a Dark Photon and an Invisible Dark Higgs Boson in μ^{+}μ^{-} and Missing Energy Final States with the Belle II Experiment

The dark photon A^{'} and the dark Higgs boson h^{'} are hypothetical particles predicted in many dark sector models. We search for the simultaneous production of A^{'} and h^{'} in the dark Higgsstrahlung process e^{+}e^{-}→A^{'}h^{'} with A^{'}→μ^{+}μ^{-} and h^{'} invisible in electron-positron collisions at a center-of-mass energy of 10.58 GeV in data collected by the Belle II experiment in 2019. With an integrated luminosity of 8.34  fb^{-1}, we observe no evidence for signal. We obtain exclusion limits at 90% Bayesian credibility in the range of 1.7-5.0 fb on the cross section and in the range of 1.7×10^{-8}-200×10^{-8} on the effective coupling ϵ^{2}×α_{D} for the A^{'} mass in the range of 4.0  GeV/c^{2}<M_{A^{'}}<9.7  GeV/c^{2} and for the h^{'} mass M_{h^{'}}<M_{A^{'}}, where ϵ is the mixing strength between the standard model and the dark photon and α_{D} is the coupling of the dark photon to the dark Higgs boson. Our limits are the first in this mass range.

Age-related change in mammographic breast density of women without history of breast cancer over a 10-year retrospective study

Background

Women with higher breast density are at higher risk of developing breast cancer. Breast density is known to affect sensitivity to mammography and to decrease with age. However, the age change and associated factors involved are still unknown. This study aimed to investigate changes in breast density and the associated factors over a 10-year period.

Materials and Methods

The study included 221 women who had undergone eight or more mammograms for 10 years (2011-2020), were between 25 and 65 years of age, and had no abnormalities as of 2011. Breast density on mammographic images was classified into four categories: fatty, scattered, heterogeneously dense, and extremely dense. Breast density was determined using an image classification program with a Microsoft Lobe's machine-learning model. The temporal changes in breast density over a 10-year period were classified into three categories: no change, decrease, and increase. An ordinal logistic analysis was performed with the three groups of temporal changes in breast density categories as the objective variable and the four items of breast density at the start, BMI, age, and changes in BMI as explanatory variables.

Results

As of 2011, the mean age of the 221 patients was 47 ± 7.3 years, and breast density category 3 scattered was the most common (67.0%). The 10-year change in breast density was 64.7% unchanged, 25.3% decreased, and 10% increased. BMI was increased by 64.7% of women. Breast density decreased in 76.6% of the category at the start: extremely dense breast density at the start was correlated with body mass index (BMI). The results of the ordinal logistic analysis indicated that contributing factors to breast density classification were higher breast density at the start (odds ratio = 0.044; 95% CI [0.025-0.076]), higher BMI at the start (odds ratio = 0.76; 95% CI [0.70-0.83]), increased BMI (odds ratio = 0.57; 95% CI [0.36-0.92]), and age in the 40s at the start (odds ratio = 0.49; 95% CI [0.24-0.99]). No statistically significant differences were found for medical history.

Conclusion

Breast density decreased in approximately 25% of women over a 10-year period. Women with decreased breast density tended to have higher breast density or higher BMI at the start. This effect was more pronounced among women in their 40s at the start. Women with these conditions may experience changes in breast density over time. The present study would be useful to consider effective screening mammography based on breast density.