Masafumi Imamura

Dr. Masafumi Imamura

Sapporo Medical University School of Medicine
orcid

Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
11 May 2021 in Cancers
Verified
Journal Article
Open access
PDF file
MIMasafumi Imamura
Masafumi Imamura
MNMinoru Nagayama
Minoru Nagayama
Daisuke KyunoDaisuke Kyuno
Daisuke Kyuno
SOshigenori ota
shigenori ota
TMTakeshi Murakami
Takeshi Murakami
ITIchiro Takemasa
Ichiro Takemasa
We aimed to identify the perioperative predictors of the early recurrence (ER) of resectable and borderline-resectable pancreatic ductal adenocarcinomas (PDACs). After surgery for a PDAC, most patients develop a recurrence. Predictive factors may therefore guide therapeutic decision-making. Patients (n = 234) who underwent a pancreatectomy for a PDAC between 2006 and 2019 were included. The postrecurrence survival (PRS) was estimated using Kaplan–Meier curves. Predictive factors for an ER were assessed using logistic regression analyses; 93 patients (39.7%) were recurrence-free at the last follow-up. Patients with an ER (n = 85, 36.3%), defined as a recurrence within the first 12 months after surgery, had 1- and 2-year PRS rates of 38.7% and 9.5%, respectively, compared with 66.9% and 37.2% for those with a late recurrence (n = 56, 23.9%; both p < 0.001). The most common site of an ER was the liver (55.3%) with a significantly shorter median overall survival time than that with either a local or a lung recurrence (14.5 months; p < 0.001). Preoperative and postoperative risk factors for an ER included a tumor size >3.0 cm (odds ratio (OR): 3.11, 95% confidence interval (CI): 1.35–7.14) and preoperative carbohydrate antigen 19-9 (CA19-9) levels >52 U/mL (OR: 3.25, 95% CI: 1.67–6.30) and a pathological tumor size >3.0 cm (OR: 2.00, 95% CI: 1.03–3.90) and postoperative carbohydrate antigen 19-9 levels >37 U/mL (OR: 2.11, 95% CI: 1.02–4.36), respectively. Preoperatively (>52 U/mL) and postoperatively (>37 U/mL) elevated CA19-9 and a tumor size >3.0 cm were independent predictors for an ER after a pancreatectomy for a PDAC.

17 December 2013 in World Journal of Surgical Oncology
Verified
Journal Article
Open access
PDF file
Daisuke KyunoDaisuke Kyuno
Daisuke Kyuno
YKYasutoshi Kimura
Yasutoshi Kimura
MIMasafumi Imamura
Masafumi Imamura
MUMotonobu Uchiyama
Motonobu Uchiyama
MIMasayuki Ishii
Masayuki Ishii
KHKoichi Hirata
Koichi Hirata
Situs inversus totalis (SIT) denotes complete right-left inversion of the thoracic and abdominal viscera. Diagnosis and surgical procedures for abdominal pathology in patients with SIT are technically more complicated because of mirror-image transposition of the visceral organs. Moreover, SIT is commonly associated with cardiovascular and hepatobiliary malformations, which make hepatobiliary-pancreatic surgery difficult. Two cases of pancreaticoduodenectomy for biliary tract carcinoma in patients with SIT are presented. Both patients had an anomaly of the hepatic artery. Advanced diagnostic imaging techniques were very important for careful preoperative planning and to prevent misunderstanding of the arrangement of the abdominal viscera. This facilitated the surgical team’s adaptation to the mirror image of the standard procedure and helped avoid intraoperative complications due to cardiovascular and hepatobiliary malformations associated with SIT. Pancreaticoduodenectomy in patients with SIT can be performed successfully with detailed preoperative assessment, use of effective techniques by the surgeon, and appropriate support by assistants.

1 January 2016 in Journal of Surgical Research
Verified
Journal Article
Closed access
MIMasafumi Imamura
Masafumi Imamura
YKYasutoshi Kimura
Yasutoshi Kimura
TITatsuya Ito
Tatsuya Ito
TKTakuro Kyuno
Takuro Kyuno
TNTakayuki Nobuoka
Takayuki Nobuoka
KHKoichi Hirata
Koichi Hirata

30 April 2019 in World Journal of Surgical Oncology
Verified
Journal Article
Open access
PDF file
HYHiroshi Yamaguchi
Hiroshi Yamaguchi
YKYasutoshi Kimura
Yasutoshi Kimura
MNMinoru Nagayama
Minoru Nagayama
MIMasafumi Imamura
Masafumi Imamura
STShingo Tanaka
Shingo Tanaka
ITIchiro Takemasa
Ichiro Takemasa
Portal annular pancreas (PAP) is a rare congenital anatomical abnormality of the pancreas in which the portal vein is encircled by aberrant parenchyma, and special attention is needed for pancreatic resections. This is the first report of central pancreatectomy (CP) in a PAP for metastatic renal cell carcinoma (RCC). A 76-year-old man who had a history of left nephrectomy for renal cancer not otherwise specified 36 years earlier and radical cystectomy for bladder cancer 4 years earlier was incidentally found to have a pancreatic tumor and a liver tumor. The pancreatic tumor was diagnosed as metastasis of clear cell RCC, and the liver tumor was diagnosed as moderately differentiated hepatocellular carcinoma (HCC) on preoperative histological evaluation. Preoperative computed tomography imaging showed a type 3A PAP, in which the main pancreatic duct (MPD) ran ventral to the portal vein (anteportal type), and the aberrant parenchyma was located cranial to the confluence of the portal vein and splenic vein (suprasplenic type). After adhesiotomy and partial liver resection, CP was performed. With intraoperative ultrasound guidance, the aberrant parenchyma of the PAP could be preserved, avoiding additional resection. Thus, two pancreatic transections were performed, creating a single-cut margin that contained the MPD in the distal pancreas. Oncologically safe margins were confirmed by intraoperative pathological diagnosis. The distal pancreas was reconstructed by pancreatojejunostomy in the routine procedures. The pathological diagnosis of the surgical specimens was identical to the preoperative diagnosis. A postoperative pancreatic fistula (POPF) developed from the proximal stump of the head of the pancreas, necessitating no specific treatment other than drainage. The patient showed no signs or symptoms of recurrent RCC or abnormal pancreatic function for 2 years after the operation, although a histologically proven new HCC lesion developed distant from the initial site 8 months after the operation. Precise preoperative evaluation of the tumor features and PAP allowed adequate surgical strategies to be planned. Intraoperative ultrasound was useful to minimize parenchymal resections of the PAP. CP is still a challenging procedure in terms of the development of POPF.

27 April 2025 in Cancers
Verified
Journal Article
Open access
PDF file
Daisuke KyunoDaisuke Kyuno
Daisuke Kyuno
HAHinae Asano
Hinae Asano
ROReona Okumura
Reona Okumura
KTKumi Takasawa
Kumi Takasawa
ATAkira Takasawa
Akira Takasawa
MOMakoto Osanai
Makoto Osanai
Background/Objectives: Pancreatic ductal adenocarcinoma is a lethal malignancy, necessitating an understanding of its molecular mechanisms for the development of new therapeutic strategies. The tight junction protein claudin-1, known to influence cellular functions in various cancers and is considered a therapeutic target, remains unclear in pancreatic cancer. Methods: This study assessed claudin-1 expression in resected pancreatic cancer samples, public databases, and pancreatic cancer cell lines. Claudin-1 knockout with CRISPR/Cas9 on poorly differentiated pancreatic cancer cell lines and a proteome analysis were performed to investigate the intracellular mechanisms of claudin-1. Results: Claudin-1 was markedly overexpressed in pancreatic ductal adenocarcinoma and intraepithelial neoplasia compared to normal ducts, and high claudin-1 levels were an independent predictor of poor prognosis. Claudin-1 knockout diminished cell proliferation, migration, invasion, and chemoresistance in pancreatic ductal adenocarcinoma. Proteome analysis revealed the significant downregulation of aldo-keto reductase family proteins (AKR1C2, AKR1C3, and AKR1B1) in claudin-1 knockout cells, which are linked to metabolic pathways. Aldo-keto reductase knockdown reduced chemoresistance, proliferation, and invasion in these cell lines. Conclusions: These findings indicate that the abnormal expression of claudin-1 promotes tumor progression and drug resistance through its interaction with aldo-keto reductase proteins, highlighting claudin-1 and aldo-keto reductase family proteins as potential biomarkers and therapeutic targets for pancreatic cancer.

22 July 2024 in Surgery Open Science
Verified
Journal Article
Open access
TMTakeshi Murakami
Takeshi Murakami
YKYasutoshi Kimura
Yasutoshi Kimura
MIMasafumi Imamura
Masafumi Imamura
MNMinoru Nagayama
Minoru Nagayama
TKToru Kato
Toru Kato
ITIchiro Takemasa
Ichiro Takemasa
Patients with resectable (R) or borderline resectable (BR) pancreatic ductal adenocarcinoma (PDAC) sometimes show unexpected liver, peritoneal, and para-aortic lymph node metastases intraoperatively. Despite radical pancreatectomy, a nonnegligible number of patients relapse within 6 months after surgery. The aim of this study was to identify the preoperative predictors of occult metastases (OM), defined as intraoperative distant metastases or within 6 months after pancreatectomy. This study included patients with R and BR PDAC who underwent curative-intent pancreatectomy or staging laparoscopy between 2006 and 2021. Multivariate logistic regression and Cox hazard analyses were performed to identify the preoperative predictors of OM and to assess the impact of these factors on prognosis after pancreatectomy. Of the 279 patients, OM was observed intraoperatively in 47 and postoperatively in 34. In the OM group, there were no differences in prognosis between patients who had intraoperative metastases and recurrence within 6 months (median survival time [MST], 18.1 vs. 12.9 months), and between patients who underwent pancreatectomy and those who did not (MST, 13.9 vs. 18.1 months). Preoperative tumor size ≥22 mm (odds ratio [OR], 2.03; 95 % confidence interval [CI], 1.16–3.53; p = 0.013) and preoperative CA19–9 level ≥ 118.8 U/mL (OR, 2.64; 95 % CI, 1.22–5.73; p = 0.014) were significant predictors of OM. Additionally, positive OM predictors were strong independent prognostic factors for overall survival after pancreatectomy (hazard ratio, 2.47; 95 % CI, 1.54–3.98; p < 0.001). Multidisciplinary treatment strategies should be considered for patients with predictors of OM to avoid inappropriate surgical interventions.