Pancreatic Duct Involvement in Well-Differentiated Neuroendocrine Tumors is an Independent Poor Prognostic Factor.
BACKGROUND
The biological behavior of well-differentiated neuroendocrine tumors of the pancreas (PNETs) is difficult to predict. This study was designed to determine whether involvement of the main pancreatic duct (MPD) serves as a poor prognostic factor for PNETs.


METHODS
The involvement of the MPD in PNETs was defined as ductal stenosis inside the tumor mass associated with distal MPDs more than twofold larger in diameter than the proximal ducts. We examined the correlation between MPD involvement and other clinicopathological parameters, including nodal metastasis and recurrence-free survival, in 101 patients treated consecutively at three referral centers in Japan. All patients underwent surgical resection.


RESULTS
MPD involvement was observed in 13 of the 101 cases (13%) and was associated with multiple unfavorable clinicopathological features (e.g., larger tumor size, higher histological grade, more frequent nodal metastasis, and higher recurrence rates). Patients with MPD involvement also showed significantly worse recurrence-free survival than did those without ductal involvement (P < 0.001), with a 5 years recurrence-free rate of 41%. On multivariate analysis, MPD involvement was significantly associated with nodal metastasis [odds ratio (OR) 16; 95% confidence interval (CI) 3.8-89; P < 0.001] and recurrence (OR 8.0; 95% CI 1.7-46; P = 0.009). The radiology-pathology correlation revealed that stenosis of the MPD was due to periductal and/or intraductal tumor invasion. Cases with MPD involvement had microscopic venous invasion (P = 0.010) and perineural infiltration (P = 0.002) more frequently than did those with no ductal infiltration.


CONCLUSIONS
MPD involvement in PNETs may serve as an imaging sign indicating an aggressive clinical course.
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Yoshihide
Y
Nanno
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan. ippeimm@gmail.com.
Ippei
I
Matsumoto
Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe, Japan.
Yoh
Y
Zen
Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe, Japan.
Kyoko
K
Otani
Department of Gastroenterological Surgery, Kagawa University Faculty of Medicine, Takamatsu, Kagawa, Japan.
Jun
J
Uemura
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Hirochika
H
Toyama
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Sadaki
S
Asari
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Tadahiro
T
Goto
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Tetsuo
T
Ajiki
Department of Gastroenterological Surgery, Kagawa University Faculty of Medicine, Takamatsu, Kagawa, Japan.
Keiichi
K
Okano
Department of Gastroenterological Surgery, Kagawa University Faculty of Medicine, Takamatsu, Kagawa, Japan.
Yasuyuki
Y
Suzuki
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, Japan.
Yoshifumi
Y
Takeyama
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Takumi
T
Fukumoto
Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Yonson
Y
Ku
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049448:Cholangiopancreatography, Magnetic Resonance; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000209:etiology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery; D010180:Pancreatectomy; D010183:Pancreatic Ducts / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D055815:Young Adult