Faculty Profiles - NAKAMURA, Masanao

Different factors are associated with conventional adenoma and serrated colorectal neoplasia.

Leonardo Zorron Cheng Tao Pu, Khizar Rana, Gurfarmaan Singh, Masanao Nakamura, Takeshi Yamamura, Doreen Siew Ching Koay, Amanda Ovenden, Suzanne Edwards, Andrew Ruszkiewicz, Yoshiki Hirooka, Mitsuhiro Fujishiro, Alastair D Burt, Rajvinder Singh

Nagoya journal of medical science Vol. 82 ( 2 ) page： 335 - 343 2020.5

Language：Japanese Publishing type：Research paper (scientific journal)

Current data shows there are differences in factors associated with colorectal neoplasia based on geographical location and cultural settings. There are no studies focusing on the association between environmental factors and colorectal polyps in Australia. The aim of this study was to prospectively evaluate the association of various factors with different colorectal neoplasia histology. We utilized a simplified one-page questionnaire for patients undergoing colonoscopy for information on age; gender; comorbidities; family history of colorectal cancer; physical activity; smoking; diet; alcohol intake; and body mass index. Factors were then evaluated for association with the presence of: (1) neoplastic lesions; (2) conventional adenomas; (3) neoplastic serrated polyps; (4) any lesions (past and present); and (5) hyperplastic polyps. 291 procedures and 260 patients were included. Factors with a p-value < 0.2 in a univariate regression were included in an initial multivariable regression model. Backwards elimination was then performed, removing one predictor at a time until only significant predictors remained. In the final multivariable model, age≥65, male gender, type-2 diabetes mellitus, active smoking and family history of colorectal cancer were found to be statistically significant predictors for the presence of colorectal neoplasia. However, the significant predictors found for conventional adenomas (older age, male gender and smoking) were different from the significant predictors for neoplastic serrated polyps (type-2 diabetes mellitus and family history of colorectal cancer). Older age, male gender, type-2 diabetes mellitus, and smoking were significantly associated with the presence of colorectal neoplasia. The factors associated with conventional adenomas differed from those associated with neoplastic serrated polyps.

DOI： 10.18999/nagjms.82.2.335

Narrow-band imaging for scar (NBI-SCAR) classification: from conception to multicenter validation. International journal

Leonardo Zorron Cheng Tao Pu, Keng Hoong Chiam, Takeshi Yamamura, Masanao Nakamura, Tyler M Berzin, Fahad F Mir, Eduardo Guimarães Hourneaux de Moura, Antonio Coutinho Madruga Neto, Doreen Siew Ching Koay, Cheong Kuan Loong, Amanda Ovenden, Suzanne Edwards, Alastair D Burt, Yoshiki Hirooka, Mitsuhiro Fujishiro, Rajvinder Singh

Gastrointestinal endoscopy Vol. 91 ( 5 ) page： 1146 - + 2020.5

Language：Japanese Publishing type：Research paper (scientific journal)

BACKGROUND AND AIMS: Surveillance post-endoscopic resection (ER) currently warrants biopsy samples from the resection site scar in most cases, although clinical practice is variable. A classification with standard criteria for scars has not yet been established. We aimed to create and validate a novel classification for post-ER scars by using specific criteria based on advanced imaging. METHODS: Key endoscopic features for scars with and without recurrence were (1) dark brown color, elongated/branched pit pattern, and dense capillary pattern and (2) whitish, pale appearance, round/slightly large pits, and irregular sparse vessels. Scars were first assessed with high-definition white-light endoscopy (HD-WLE) followed by interrogation with narrow-band imaging (NBI). Scars with at least 2 concordant characteristics were diagnosed with "high confidence" for NBI for scar (NBI-SCAR) classification. The final endoscopic predictions were correlated with histopathology. The primary outcome was the difference in sensitivity between NBI-SCAR and HD-WLE predictions. Secondary outcomes included the validation of our findings in 6 different endoscopy settings (Australia, United States, Japan, Brazil, Singapore, and Malaysia). The validation took place in 2 sessions separated by 2 to 3 weeks, each with 10 one-minute videos of post-ER scars on underwater NBI with dual focus. Inter-rater and intrarater reliability were calculated with Fleiss' free-marginal kappa and Bennett et al. S score, respectively. RESULTS: One hundred scars from 82 patients were included. Ninety-five scars were accurately predicted with high confidence by NBI-SCAR in the exploratory phase. NBI-SCAR sensitivity was significantly higher compared with HD-WLE (100% vs 73.7%, P < .05). In the validation phase, similar results were found for endoscopists who routinely perform colonoscopies and use NBI (sensitivity of 96.4%). The inter-rater and intrarater reliability throughout all centers were, respectively, substantial (κ = .61) and moderate (average S = .52) for this subset. CONCLUSIONS: NBI-SCAR has a high sensitivity and negative predictive value for excluding recurrence for endoscopists experienced in colonoscopy and NBI. In this setting, this approach may help to accurately evaluate or resect scars and potentially mitigate the burden of unnecessary biopsy samples.

DOI： 10.1016/j.gie.2019.08.036

Diagnosis of vascular invasion in pancreatic ductal adenocarcinoma using endoscopic ultrasound elastography. International journal

Kenta Yamada, Hiroki Kawashima, Eizaburo Ohno, Takuya Ishikawa, Hiroyuki Tanaka, Masanao Nakamura, Ryoji Miyahara, Masatoshi Ishigami, Yoshiki Hirooka, Mitsuhiro Fujishiro

BMC gastroenterology Vol. 20 ( 1 ) page： 81 - 81 2020.3

Language：Japanese Publishing type：Research paper (scientific journal)

BACKGROUND: Vascular invasion is an important criterion for resectability and deciding the therapeutic strategy for pancreatic ductal adenocarcinoma (PDAC), but imaging diagnosis is currently difficult. Endoscopic ultrasound (EUS) elastography (EG) images have band-like artifacts on the border between tumor and vessel due to different movement if the tumor is not connected to the vessel, i.e., no invasion. Based on this phenomenon, we assessed the usefulness of EUS-EG in the diagnosis of vascular invasion in PDAC. METHODS: The subjects were 44 out of 313 patients with PDAC who underwent EUS between January 2015 and November 2018, followed by surgery, no chemotherapy or radiotherapy, and pathological evaluation. Diagnostic accuracies of vascular invasion using dynamic computed tomography (CT), EUS B-mode and EUS-EG were compared with histopathological diagnosis. RESULTS: In 44 subjects (48 sites) who underwent both dynamic CT and EUS-B mode, the sensitivity, specificity and accuracy were 0.733, 0.697 and 0.708 on dynamic CT (48 sites); 0.733, 0.606 and 0.646 in EUS B-mode (48 sites); and 0.917, 0.900 and 0.906 in EUS-EG (32 sites). In 27 subjects (29 sites) with a tumor contacting a vessel with no vascular obstruction or stenosis on dynamic CT, the sensitivity, specificity and accuracy were 0.556, 0.750 and 0.690 on dynamic CT; 0.667, 0.700 and 0.690 in EUS B-mode; and 0.889, 0.850 and 0.862 in EUS-EG. CONCLUSIONS: These results suggest that EUS combined with EG improves diagnostic performance of vascular invasion in PDAC, especially in cases of which vascular invasion cannot be clearly assessed by dynamic CT.

DOI： 10.1186/s12876-020-01228-9

Double-balloon endoscopic retrograde cholangiopancreatography for patients who underwent liver operation: A retrospective study. International journal

Ryo Nishio, Hiroki Kawashima, Masanao Nakamura, Eizaburo Ohno, Takuya Ishikawa, Takeshi Yamamura, Keiko Maeda, Tsunaki Sawada, Hiroyuki Tanaka, Daisuke Sakai, Ryoji Miyahara, Masatoshi Ishigami, Yoshiki Hirooka, Mitsuhiro Fujishiro

World journal of gastroenterology Vol. 26 ( 10 ) page： 1056 - 1066 2020.3

Language：Japanese Publishing type：Research paper (scientific journal)

BACKGROUND: Double-balloon endoscopic retrograde cholangiography (DB-ERC) is widely performed for biliary diseases after reconstruction in gastrointestinal surgery, but there are few reports on DB-ERC after hepatectomy or living donor liver transplantation (LDLT). AIM: To examine the success rates and safety of DB-ERC after hepatectomy or LDLT. METHODS: The study was performed retrospectively in 26 patients (45 procedures) who underwent hepatectomy or LDLT (liver operation: LO group) and 40 control patients (59 procedures) who underwent pancreatoduodenectomy (control group). The technical success (endoscope reaching the choledochojejunostomy site), diagnostic success (performance of cholangiography), therapeutic success (completed interventions) and overall success rates, insertion and procedure (completion of DB-ERC) time, and adverse events were compared between these groups. RESULTS: There were no significant differences between LO and control groups in the technical [93.3% (42/45) vs 96.6% (57/59), P = 0.439], diagnostic [83.3% (35/42) vs 83.6% (46/55), P = 0.968], therapeutic [97.0% (32/33) vs 97.7% (43/44), P = 0.836], and overall [75.6% (34/45) vs 79.7% (47/59), P = 0.617] success rates. The median insertion time (22 vs 14 min, P < 0.001) and procedure time (43.5 vs 30 min, P = 0.033) were significantly longer in the LO group. The incidence of adverse events showed no significant difference [11.1% (5/45) vs 6.8% (4/59), P = 0.670]. CONCLUSION: DB-ERC after liver operation is safe and useful but longer time is required, so should be performed with particular care.

DOI： 10.3748/wjg.v26.i10.1056

Microbiota profile is different for early and invasive colorectal cancer and is consistent throughout the colon. Reviewed

Zorron Cheng Tao Pu L, Yamamoto K, Honda T, Nakamura M, Yamamura T, Hattori S, Burt AD, Singh R, Hirooka Y, Fujishiro M

Journal of gastroenterology and hepatology Vol. 35 ( 3 ) page： 433 - 437 2020.3

Usefulness of Endoscopic Ultrasound Elastography Combined With the Strain Ratio in the Estimation of Treatment Effect in Autoimmune Pancreatitis. International journal

Takuya Ishikawa, Hiroki Kawashima, Eizaburo Ohno, Hiroyuki Tanaka, Keiko Maeda, Tsunaki Sawada, Takeshi Yamamura, Kazuhiro Furukawa, Masanao Nakamura, Ryoji Miyahara, Masatoshi Ishigami, Mitsuhiro Fujishiro

Pancreas Vol. 49 ( 2 ) page： E21 - E22 2020.2

Relationship Between Adverse Events and Microbiomes in Advanced Hepatocellular Carcinoma Patients Treated With Sorafenib. International journal

Kenta Yamamoto, Teiji Kuzuya, Takashi Honda, Takanori Ito, Yoji Ishizu, Masanao Nakamura, Ryoji Miyahara, Hiroki Kawashima, Masatoshi Ishigami, Mitsuhiro Fujishiro

Anticancer research Vol. 40 ( 2 ) page： 665 - 676 2020.2

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND/AIM: Sorafenib results in several adverse events, the mechanism and predictors of which are unknown. Recently, it was reported that metabolism by microbiome changes the structure and effects of drugs. The blood levels of sorafenib may be affected by enterohepatic recycling of sorafenib due to microbial enzymes in the gut. We evaluated the relationship between adverse events caused by sorafenib treatment and microbiome in patients with advanced hepatocellular carcinoma. MATERIALS AND METHODS: Twenty-five patients were classified into two groups based on the presence of hand-foot syndrome (HFS) or diarrhea within 12 weeks post-sorafenib treatment. Before sorafenib treatment, the fecal samples were analyzed targeting the V3-V4 region of 16s ribosomal RNA. Microbiome and predicted functional gene were compared between two groups. RESULTS: The non-HFS group had a richer abundance of Veillonella, Bacillus, Enterobacter, Faecalibacterium, Lachnospira, Dialister, and Anaerostipes than the HFS group at genus level. Carotenoid biosynthesis and bacterial invasion of epithelial cells were enriched in the HFS group. The former three bacteria are classified as oral-origin bacteria, and the two predicted functions are associated with dysbiosis. The non-diarrhea group had a higher abundance of Butyricimonas and a lower abundance of Citrobacter, Peptostreptococcus, and Staphylococcaceae than the diarrhea group. Eight categories of predicted functional genes were detected with differences between the two groups. CONCLUSION: The non-HFS group had a higher relative abundance of oral-origin bacteria, which likely led to more robust dysbiosis in the gut. This dysbiosis may affect enterohepatic recycling. Additionally, the metabolism of these short-chain fatty acids in the gut may be different between the diarrhea and non-diarrhea groups.

DOI： 10.21873/anticanres.13996

Generation of magnifying endoscopic images of gastric neoplasms based on an all-in-focus algorithm. International journal

Kenichi Matsui, Kohei Funasaka, Ryoji Miyahara, Kazuhiro Furukawa, Masanobu Matsushita, Takeshi Yamamura, Takuya Ishikawa, Eizaburo Ohno, Masanao Nakamura, Hiroki Kawashima, Osamu Watanabe, Kenichi Ohara, Yoshiki Hirooka, Hidemi Goto

Journal of gastroenterology and hepatology Vol. 35 ( 1 ) page： 65 - 70 2020.1

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND AND AIM: Magnifying endoscopy is useful for diagnosis of early gastrointestinal neoplasms by visualizing microvascular (MV) and microsurface (MS) structures of the mucosa when combined with image-enhanced endoscopy. However, precise control of the endoscope is needed because the depth of focus is narrow and the target may move. These problems may be overcome by the all-in-focus (AIF) technique, which was developed in the engineering field. The aim of the study was to evaluate magnifying endoscopic image with AIF algorithm. METHODS: Twenty gastric neoplasms were examined. Images were acquired at 80× magnification and converted to endoscopic images with an AIF algorithm (EI-AIF). The focus area and MV and MS patterns in the original image and the EI-AIF were compared on a 5-point Likert scale, where 5 indicates that the EI-AIF was superior. Intraclass correlation coefficients (ICCs) were used to assess the inter-evaluator reliability. An image quality measurement value was calculated for each image as an indicator of the degree of focus. RESULTS: The scores for focus area, MV, and MS were 4.78 ± 0.45 (ICC = 0.63), 4.12 ± 0.76 (ICC = 0.70), and 4.72 ± 0.52 (ICC = 0.45), respectively, with the EI-AIF significantly superior for all three items (P < 0.05 by Student's t-test). ICCs for the focus area and MV were > 0.60, indicating strong inter-evaluator reliability. Image quality measurement was higher for the EI-AIF compared with the original image in every case. CONCLUSIONS: Endoscopic observation with AIF algorithm gives a better image quality that allows easier evaluation of MV and MS patterns. This technique may resolve the difficulties with magnifying endoscopic observation.

DOI： 10.1111/jgh.14792

Color information from linked color imaging is associated with invasion depth and vascular diameter in superficial esophageal squamous cell carcinoma. Reviewed

Kobayashi K, Miyahara R, Funasaka K, Furukawa K, Sawada T, Maeda K, Yamamura T, Ishikawa T, Ohno E, Nakamura M, Kawashima H, Nakaguro M, Okumura Y, Hirooka Y, Fujishiro M

Digestive endoscopy : official journal of the Japan Gastroenterological Endoscopy Society Vol. 32 ( 1 ) page： 65 - 73 2020.1

Prognostic impact of PD-L1 expression in primary gastric and intestinal diffuse large B-cell lymphoma. Reviewed

Ishikawa E, Nakamura M, Shimada K, Tanaka T, Satou A, Kohno K, Sakakibara A, Furukawa K, Yamamura T, Miyahara R, Nakamura S, Kato S, Fujishiro M

Journal of gastroenterology Vol. 55 ( 1 ) page： 39 - 50 2020.1

炎症性腸疾患の最新治療の現状と今後当院での潰瘍性大腸炎における生物学的製剤の治療

澤田つな騎, 中村正直, 山村健史, 前田啓子, 水谷泰之, 石川恵理, 西川貴広, 服部峻, 山田啓策, 久野剛史, 梶川豪, 橋口裕樹, 江崎正哉, 喜田裕一, 濱崎元伸, 村手健太郎, 藤城光弘

日本消化管学会雑誌 Vol. 4 ( Suppl. ) page： 239 - 239 2020.1

Nasal patency as a factor for successful transnasal endoscopy.

Toshihiko Nagaya, Ryoji Miyahara, Kohei Funasaka, Kazuhiro Furukawa, Takeshi Yamamura, Takuya Ishikawa, Eizaburo Ohno, Masanao Nakamura, Hiroki Kawashima, Tsutomu Nakashima, Seiichi Nakata, Yoshiki Hirooka

Nagoya journal of medical science Vol. 81 ( 4 ) page： 587 - 595 2019.11

Language：English Publishing type：Research paper (scientific journal)

In recent years, transnasal endoscopy had been more widely accepted for its safety and convenience, and although it can lead to a weaker pharyngeal reflex, compared with the effects of transoral endoscopy, examinees often suffer intolerable pain and discomfort during passage of the endoscope through the nasal cavity. The aim of this study was to estimate the relationship between the uncomfortable factors during transnasal endoscopy and nasal patency. The subjects comprised 23 consecutive patients who underwent transnasal endoscopy from October 2007 to April 2009 at our Gastroenterology and Otorhinolaryngology Departments. Immediately prior to endoscopy, the left and right nasal resistance was measured with an active anterior rhinomanometer; a value of 100 Pa was determined as nasal resistance. The transnasal endoscope was inserted in the subjectively preferred side by the examinee. Thereafter, the subjects were asked to fill in a questionnaire on physical tolerance during the procedure, to quantify the sensations of nasal pain, nausea, and choking on a 10-point visual analogue scale. The mean scores were 3.0 ± 2.7 for nasal pain, 1.7 ± 2.0 for choking, and 1.6 ± 1.9 for nausea. The most intolerable factor among the complaints was pain (45%), which was followed by nausea (18%) and choking (9%). Unilateral nasal resistance was significantly related with nasal pain only (P = 0.0135). In conclusion, the most difficult problem during transnasal endoscopy was pain, which was related to nasal patency. We successfully demonstrated the clinical significance of nasal patency in determining the side of insertion for transnasal endoscopy.

DOI： 10.18999/nagjms.81.4.587

Feasibility and usefulness of endoscopic ultrasonography-guided shear-wave measurement for assessment of autoimmune pancreatitis activity: a prospective exploratory study.

Eizaburo Ohno, Yoshiki Hirooka, Hiroki Kawashima, Takuya Ishikawa, Hiroyuki Tanaka, Daisuke Sakai, Yoji Ishizu, Teiji Kuzuya, Masanao Nakamura, Takashi Honda

Journal of medical ultrasonics (2001) Vol. 46 ( 4 ) page： 425 - 433 2019.10

Language：English Publishing type：Research paper (scientific journal)

PURPOSE: To assess the feasibility and the clinical usefulness of a newly developed endoscopic ultrasonography (EUS) shear-wave elastography technique (EUS shear-wave measurement: EUS-SWM) in the diagnosis and treatment of autoimmune pancreatitis (AIP). METHODS: Tissue elasticity was measured in the pancreas in 160 patients. The success rate of EUS-SWMs, the velocity of the shear wave (Vs, m/s), and the reliability index of the Vs measurement (VsN) were evaluated, and the elasticity (median Vs) was compared between AIP patients (n = 14) and normal controls. RESULTS: A total of 3837 EUS-SWMs were performed without adverse events. Overall, 97.6% (3743/3837) were successful. The median VsN was 74%. The median Vs values of the pancreas were as follows: 2.22 m/s in the pancreatic head (push position), 2.36 m/s in the head (pull position), 1.99 m/s in the body, and 2.25 m/s in the tail. The median Vs of the AIP group (2.57 m/s) was significantly higher than that of the normal controls (1.89 m/s) (P = 0.0185). The mean Vs significantly decreased from 3.32 m/s to 2.46 m/s after steroid therapy (n = 6) (P = 0.0234). CONCLUSION: EUS-SWM is feasible and generates credible results. EUS-SWM was a useful method for assessment of the effect of steroid therapy in AIP patients.

DOI： 10.1007/s10396-019-00944-4

EUS Elastographyを用いた膵癌の脈管浸潤診断

山田健太, 廣岡芳樹, 川嶋啓揮, 大野栄三郎, 石川卓哉, 田中浩敬, 酒井大輔, 飯田忠, 西尾亮, 鈴木博貴, 植月康太, 八鹿潤, 芳川昌功, 宜保憲明, 青木聡典, 中村正直, 宮原良二, 石上雅敏, 藤城光弘

Gastroenterological Endoscopy Vol. 61 ( Suppl.2 ) page： 2196 - 2196 2019.10

Specific members of gut microbiota predict mucosal healing in Crohn's disease

Hattori S., Nakamura M., Yamamura T., Maeda K., Sawada T., Mizutani Y., Yamamoto K., Pu L. Zorron Cheng Tao, Honda T., Ishikawa T., Furukawa K., Ohno E., Miyahara R., Kawashima H., Fujishiro M.

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY Vol. 34 page： 152 - 152 2019.9

Objective evaluation of the therapeutic effect of ustekinumab on Crohn's disease

Yamamura T., Nakamura M., Murate K., Maeda K., Sawada T., Mizutani Y., Nishikawa T., Hattori S., Yamamoto K., Pu L. Zorron Cheng Tao, Ishikawa T., Furukawa K., Ohno E., Miyahara R., Kawashima H., Fujishiro M.

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY Vol. 34 page： 145 - 145 2019.9

The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography. International journal

Kiyotaka Hashizume, Yoshiki Hirooka, Hiroki Kawashima, Eizaburo Ohno, Takuya Ishikawa, Manabu Kawai, Hiroki Suhara, Tomoaki Takeyama, Toshinari Koya, Hiroyuki Tanaka, Daisuke Sakai, Takeshi Yamamura, Kazuhiro Furukawa, Kohei Funasaka, Masanao Nakamura, Ryoji Miyahara, Osamu Watanabe, Masatoshi Ishigami, Takamichi Kuwahara, Senju Hashimoto, Hidemi Goto

Ultrasound in medicine & biology Vol. 45 ( 8 ) page： 2242 - 2247 2019.8

Language：English Publishing type：Research paper (scientific journal)

Evaluation of the pancreatic elastic modulus (PEM) using shear wave elastography (SWE) requires at least 5 measurements to ensure reproducibility. The aim of this study was to evaluate improvement in reproducibility of SWE, using the propagation display method in normal pancreas ([NP] phase 1) and to examine the differences in PEM between NP and chronic pancreatitis (CP), intraductal papillary mucinous neoplasm (IPMN) and autoimmune pancreatitis ([AIP] phase 2). In phase 1, the measurement success rate, median PEM in repeated measurements and appropriate number of SWE measurements were determined in 109 cases with NP. In phase 2, PEM was measured in CP (n = 10), IPMN (n = 31) and AIP (n = 5), using the required number of SWE measurements determined in phase 1. In phase 1, the measurement success rate was 93.9% (92/109 cases). The median PEM for NP was 14.6 kPa and the appropriate number of SWE measurements was at least 3. In phase 2, the median PEMs in CP, IPMN and AIP were 19.6, 18.1 and 17.2 kPa, respectively, with significant differences between NP and CP (p = 0.0133) and between NP and IPMN (p = 0.0436). Use of the propagation display method in SWE improves the reproducibility of measurement of PEM.

DOI： 10.1016/j.ultrasmedbio.2019.04.003

Comparison of 8- and 10-mm diameter fully covered self-expandable metal stents: A multicenter prospective study in patients with distal malignant biliary obstruction. International journal

Hiroki Kawashima, Senju Hashimoto, Eizaburo Ohno, Takuya Ishikawa, Tomomasa Morishima, Hiroshi Matsubara, Hiroyuki Sugimoto, Koji Nonogaki, Akira Kanamori, Kazuo Hara, Takamichi Kuwahara, Masanao Nakamura, Ryoji Miyahara, Masatoshi Ishigami, Masahiko Ando, Yoshiki Hirooka

Digestive endoscopy : official journal of the Japan Gastroenterological Endoscopy Society Vol. 31 ( 4 ) page： 439 - 447 2019.7

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: The time to recurrent biliary obstruction (TRBO) of unresectable distal malignant biliary obstruction is generally thought to be longer when a self-expandable metal stent (SEMS) with a thicker inner diameter is used for drainage, but the dependence on the inner diameter using a fully covered SEMS (FCSEMS) is uncertain. The objective of this multicenter prospective study was to compare TRBO and adverse events, such as cholecystitis and pancreatitis, in treatment of patients with unresectable malignant biliary obstruction using 8- and 10-mm diameter FCSEMS. METHODS: Eighteen tertiary-care centers participated in the study. Patients were allocated to the 8- and 10-mm diameter groups. TRBO, non-inferiority of the 8-mm FCSEMS, overall survival time, frequency and type of adverse events, and non-recurrent biliary obstruction (RBO) rate at the time of death were compared between the two groups. RESULTS: Median TRBO did not differ significantly between the 8-mm (n = 102) and 10-mm (n = 100) groups (275 vs 293 days, P = 0.971). The hazard ratio of the 8- to 10-mm groups was 0.90 (80% confidence interval, 0.77-1.04; upper limit lower than the acceptable hazard ratio [1.33] of the null hypothesis). Based on these findings, the 8-mm diameter stent was determined to be non-inferior to the 10-mm diameter stent. Survival time, incidence of adverse events and non-RBO rate at the time of death did not differ significantly between the two groups. CONCLUSIONS: Time to RBO with an 8-mm diameter FCSEMS was non-inferior to that with a 10-mm diameter FCSEMS. This finding is important for development of future SEMS.

DOI： 10.1111/den.13366