Observational study of the incidence of pancreatic and extrapancreatic malignancies during surveillance of patients with branch-duct intraductal papillary mucinous neoplasm.

Objective: This observational analysis assessed the incidence of pancreatic and extrapancreatic malignancies in BD-IPMN patients.
Background: Previous studies showed that progression to malignancy of pancreatic branch-duct (BD) intraductal papillary mucinous neoplasm (IPMN) is infrequent and that extrapancreatic malignancies (EPMs) occur with unusual frequency in IPMN patients.
Methods: Patients observed from 2000 to 2012 and enrolled in a surveillance protocol according to the current guidelines were considered eligible for the study. Only patients with follow-up of more than 12 months were evaluated. The incidence of EPM was calculated only in patients who were free of them at the time of IPMN diagnosis. Data were compared with Italian cancer statistics. The standardized incidence ratios (SIRs) and the 5- and 10-year incidence rates were estimated.
Results: The study population consisted of 569 patients. At a median follow-up of 56 months, 9 patients developed a pancreatic malignancy. Of these, 5 were unresectable. The SIR was 9.21 [95% confidence interval (CI), 1.85-26.91] in males, and 11.94 (95% CI, 4.36-26.0) in females, with a 5-year cumulative incidence of 1.4%. The EPM incidence analysis was performed in 456 patients. Thirty EPMs developed during the follow-up. The SIR was 1.40 (95% CI, 0.72-2.45) in males and 1.37 (95% CI, 0.81-2.16) in females. The 5-year rate of developing any EPM was 5.7%.
Conclusions: BD-IPMN patients are at risk of pancreatic carcinogenesis. Although the 5-year incidence rate was as low as 1.4%, the surveillance protocol based on the current guidelines failed to identify a small subset of patients who progressed to advanced disease. Patients with BD-IPMN are not at risk of extrapancreatic carcinogenesis.