Details of a Researcher - Tanaka, Masayuki

Tanaka, Masayuki

写真a

Affiliation: School of Medicine, Department of Surgery (General and Gastroenterological Surgery) ( Shinanomachi )

Position: Instructor

External Links

https://orcid.org/0000-0003-0335-3912

Scopus Paper Info

Paper Count: 69 Citation Count: 959 h-index: 17

Click to view the Scopus page. The data was downloaded from Scopus API in August 23, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Papers 【 Display / hide 】

Early clinical impact of mesenteric Kocherization in robotic pancreaticoduodenectomy: a propensity score–matched comparative study

Mishima K., Kawamoto J., Kitago M., Nakano Y., Tanaka M., Hori S., Hasegawa Y., Abe Y., Kitagawa Y.

Surgical Endoscopy 40 ( 6 ) 4733 - 4741 2026.06

ISSN 09302794

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Background: Although robotic pancreaticoduodenectomy (RPD) offers several technical advantages, prolonged operative time remains a major clinical challenge. Mesenteric Kocherization (MK) has recently been introduced as a technical modification for mobilizing the duodenum and pancreatic head during RPD. The present study evaluated the early clinical impact of MK on operative efficiency and perioperative outcomes. Methods: We retrospectively reviewed 56 consecutive patients who underwent totally robotic pancreaticoduodenectomy between July 2021 and June 2025. Conventional Kocherization (CK) was performed in 36 patients and MK in 20 patients. The primary outcome was total operative time. Secondary outcomes included console time, Kocherization time, estimated blood loss, transfusion, harvested lymph nodes, R0 resection rate, major postoperative complications (Clavien–Dindo ≥ IIIa), time to first oral intake, and 90-day unplanned readmission rate. To reduce selection bias, propensity score matching was performed using a 1:2 allocation (MK:CK). Results: In the full cohort, operative time tended to be shorter in the MK group than in the CK group (560 [516–598] vs. 592 [556–667] min; p = 0.057). Kocherization time was significantly shorter with MK (28 [27–36] vs. 50 [40–58] min; p < 0.001), while estimated blood loss was comparable (p = 0.875). After propensity score matching (MK n = 11; CK n = 22), MK was associated with significantly shorter total operative time (533 [511–575] vs. 580 [557–611] min; p = 0.031) and Kocherization time (28 [24–30] vs. 49 [43–55] min; p < 0.001). Blood loss, R0 resection rate, and major postoperative complications were comparable between groups. Conclusions: Mesenteric Kocherization was associated with improved operative efficiency in RPD, primarily through shortening the resection phase of the procedure while maintaining perioperative safety.
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Neoadjuvant chemotherapy versus upfront surgery for perihilar cholangiocarcinoma: a propensity score matching analysis

Sonoda K., Abe Y., Chiba N., Nishiyama R., Mihara K., Hayatsu S., Takano K., Takemura R., Kitago M., Hasegawa Y., Hori S., Tanaka M., Mishima K., Nakano Y., Kawachi S., Kitagawa Y.

HPB 28 ( 5 ) 666 - 675 2026.05

ISSN 1365182X

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Background: Neoadjuvant chemotherapy (NAC) may improve outcomes in perihilar cholangiocarcinoma (PHC); however, its efficacy compared with upfront surgery (US) for resectable PHC remains unclear. We compared survival and clinicopathological characteristics between NAC and US in patients with technically resectable PHC, using propensity score matching (PSM). Methods: We retrospectively analyzed 261 patients with resectable PHC who underwent surgical treatment (2016–2024) across multiple institutions. Among them, 50 received NAC and 199 underwent US. The 38 patients receiving NAC were matched 1:1 with patients undergoing US using PSM. Overall survival (OS) and progression-free survival (PFS) were compared between groups. Pathological response to NAC and its association with chemotherapy doses were also evaluated. Results: Before PSM, OS and PFS did not differ significantly between the US and NAC groups. After PSM, OS did not differ significantly between groups, but PFS was significantly longer in the NAC group, where patients with a therapeutic-effect grade ≥1b had better PFS than those with US. Grade ≥1b response was associated with receiving ≥7 NAC doses. Discussion: NAC may improve PFS in selected patients with resectable PHC, especially those showing major pathological responses. Prospective studies should validate these findings and define optimal selection criteria and regimens.
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Genomic Concordance Between Primary and Oligo-Recurrent Lesions in Pancreatobiliary Cancer

Sonoda K., Hayashi H., Kitago M., Abe Y., Hasegawa Y., Hori S., Tanaka M., Nakano Y., Nishihara H., Kitagawa Y.

Journal of Hepato Biliary Pancreatic Sciences 33 ( 4 ) 322 - 329 2026.04

ISSN 18686974

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Background/Purpose: The introduction of oligo-recurrence (OR) as a subtype of metastasis offered new hope, suggesting that local therapies may lead to prolonged survival/cure in selected cases. This study compared the genomic alterations between primary tumors and matched OR lesions in patients with pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA). Methods: Eight patients with OR of PDAC or CCA were eligible. Genomic DNA was extracted from the tissue samples of primary tumors and matched OR lesions. Comprehensive genomic profiling (CGP) was performed using a panel of 216 cancer-related genes. The genomic profiles of the two groups were compared. Results: Among 17 tumor samples from eight patients, 32 genomic mutations were identified in nine genes. A total of 48 copy number alterations were found across 31 distinct genes. Driver genomic mutations were concordant between the primary tumors and OR lesions in all cases, whereas differences in passenger mutations were observed in two cases. Five of the eight patients remained recurrence-free, including two pancreatic cancer cases who remained recurrence-free for > 4 years after surgery. Conclusions: The genomic mutation statuses of primary tumors and OR lesions were concordant, and patients' prognosis was significantly better than that of patients with other Stage IV cancers.
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Preoperative CD44v6-positive extracellular vesicles as a prognostic biomarker in pancreatic ductal adenocarcinoma

Uematsu Y., Matsuda S., Kitago M., Uemura S., Shimane G., Nakano Y., Tanaka M., Hori S., Hasegawa Y., Abe Y., Masugi Y., Takemura R., Kitagawa Y.

Journal of Gastroenterology 61 ( 3 ) 345 - 357 2026.03

ISSN 09441174

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Background: CD44v6-positive extracellular vesicles (EVs) released by cancer cells drive tumor progression and liver metastasis. This study aimed to evaluate CD44v6-positive extracellular vesicles (EVs) as prognostic markers for pancreatic ductal adenocarcinoma (PDAC), a disease with poor prognosis. Methods: Plasma samples from 100 patients with hepatobiliary and pancreatic diseases were retrospectively analyzed. Non-pancreatic and unresectable pancreatic cancer cases were included as control groups for cross-sectional comparisons, whereas prognostic analysis using preoperative plasma samples was limited to resected PDAC. EVs were defined based on CD9, CD63, and CD81 membrane antigens, and the proportion of CD44v6-positive EVs was measured using nano-flow cytometry. CD44v6 expression in resected PDAC tissues was assessed using immunohistochemistry. Results: The proportion of CD44v6-positive EVs was significantly higher in patients with pancreatic cancer than in those without cancer (P = 0.0009). High CD44v6 expression in resected PDAC tissues correlated with elevated CD44v6-positive EVs in the plasma. Patients with CD44v6-positive EVs ≥ 31% had significantly poorer recurrence-free survival (P = 0.0008) and overall survival (P = 0.045) than those with < 31% EVs. Multivariate analysis confirmed CD44v6-positive EVs ≥ 31% were independent prognostic factors for recurrence-free (P = 0.005) and overall survival (P = 0.037), and a predictor of early liver metastasis (P = 0.001). Conclusions: These findings highlight the potential of preoperative quantification of CD44v6-positive EVs as a biomarker for risk stratification and treatment optimization in PDAC.
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Surgical Outcomes of Non-Benchmark Perihilar Cholangiocarcinoma

Sugiura T., Kawakatsu S., Noji T., Ito H., Abe Y., Kishi Y., Mizuno T., Otsuka S., Takahashi Y., Tanaka M., Ebata T., Hirano S.

Annals of Surgery Publish Ahead of Print 2026.02

ISSN 00034932

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Objective: – To evaluate short- and long-term surgical outcomes in non-benchmark (non-BM) patients with perihilar cholangiocarcinoma (pCCA) using a multicenter cohort from Japan. Background: – Benchmark (BM) criteria have been proposed to standardize surgical outcomes in complex hepatopancreatobiliary procedures. However, BM studies typically exclude patients with significant medical comorbidities or those requiring technically demanding procedures. As a result, the majority of real-world pCCA cases, classified as non-BM, remain underrepresented in the literature, and their outcomes are insufficiently characterized. Methods: – Between 2014 and 2018, a total of 648 patients underwent curative intent resection for pCCA at six high volume centers in Japan. Among them, 412 patients (64%) were categorized as non-BM and 236 patients (36%) as BM according to established surgical and medical exclusion criteria. Perioperative and oncologic outcomes were analyzed and compared with benchmark thresholds previously reported in the literature. Non-BM cases were further stratified into surgical, medical, and dual subgroups for subgroup analysis. Results: – The median operative time (644 minutes), intraoperative blood loss (1185 mL), and postoperative hospital stay (31 d) exceeded BM thresholds. Nevertheless, most postoperative outcomes, including Grade B/C post-hepatectomy liver failure (16.7%), bile leakage (22.8%), and in-hospital mortality (2.9%), remained within benchmark reference values. The median overall survival was 46.0 months, with 1-, 3-, and 5-year survival rates of 85.8%, 55.0%, and 37.1%, respectively. Subgroup analysis revealed decreasing survival with increasing complexity: 5-year survival rates were 50.5% in medical, 34.1% in surgical, and 15.4% in dual non-BM patients. Notably, left trisectionectomy was associated with the highest mortality (9.5%) among all procedures. Conclusions: – Despite increased surgical complexity and patient-related risk factors, non-BM pCCA patients can achieve acceptable perioperative and long-term outcomes when treated at experienced, high-volume centers. Stratification by non-BM subgroup provides meaningful prognostic insight and may help guide surgical decision-making in complex pCCA cases.
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