title: Natural history of intraductal papillary mucinous tumors of the pancreas: actuarial risk of malignancy.
abstract: OBJECTIVE
  Natural history of intraductal papillary mucinous tumors of the pancreas (IPMTs) is unknown. Cross-sectional studies suggest that exclusive branch duct (BD) involvement is associated with a lower risk of carcinoma than main pancreatic duct (MPD) involvement. The aim of our study was to calculate longitudinal risk of malignant transformation of IPMT since the first sign.
  
  
  METHODS
  All the patients with a diagnosis of highly probable or histologically proven IPMT were included. Actuarial risks of occurrence of at least low-grade dysplasia (>or=LGD), high-grade dysplasia (>or=HGD), or invasive carcinoma (IC) were calculated by Kaplan-Meier method from the first sign attributable to IPMT. The risks according to sex, acute pancreatitis, tumor size, and involvement of MPD were compared by log-rank test.
  
  
  RESULTS
  One hundred six patients were included with a proven (n = 76) or probable (n = 30) IPMT. The tumor was confined to BD in 53 cases. Median duration since the onset of the first sign to the end of follow-up was 21 months (range, 0-241). Ten-year actuarial risk that IPMT grade was >or=LGD, >or=HGD, or IC was 67%, 49%, and 29%, respectively. The only morphologic risk factor of malignant transformation was involvement of MPD, with a 5-year actuarial risk of >or=HGD of 63% in the MPD group compared with 15% in the BD group (P < .001).
  
  
  CONCLUSIONS
  Longitudinal risk of at least HGD or IC is time-dependent. Patients with BD IPMT present a much lower risk, justifying a nonoperative surveillance.
authors.affiliation: Pôle des Maladies de L'Appareil Digestif, Service de Gastroentérologie-Pancrétologie, Hôpital Beaujon, Clichy, France. philippe.levy@bjn.aphp.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Lévy
authors.forename: Vincent
authors.initials: V
authors.lastname: Jouannaud
authors.forename: Dermot
authors.initials: D
authors.lastname: O'Toole
authors.forename: Anne
authors.initials: A
authors.lastname: Couvelard
authors.forename: Marie Pierre
authors.initials: MP
authors.lastname: Vullierme
authors.forename: Laurent
authors.initials: L
authors.lastname: Palazzo
authors.forename: Alain
authors.initials: A
authors.lastname: Aubert
authors.forename: Philippe
authors.initials: P
authors.lastname: Ponsot
authors.forename: Alain
authors.initials: A
authors.lastname: Sauvanet
authors.forename: Frédérique
authors.initials: F
authors.lastname: Maire
authors.forename: Olivia
authors.initials: O
authors.lastname: Hentic
authors.forename: Pascal
authors.initials: P
authors.lastname: Hammel
authors.forename: Philippe
authors.initials: P
authors.lastname: Ruszniewski
mesh_terms: D000206:Actuarial Analysis; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic; D018292:Cystadenoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010183:Pancreatic Ducts; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D018570:Risk Assessment; D012307:Risk Factors