Long-Term Risk of Malignancy in IPMNs

Long-Term Risk of Malignancy in IPMNs

To evaluate long-term outcome of patients with branch-duct intraductal papillary mucinous neoplasms (IPMNs), particularly those after 5 years of surveillance, incidence of IPMN-derived carcinoma was analyzed with concomitant ductal adenocarcinoma (pancreatic ductal adenocarcinoma – PDAC) over 20 years in a large population of patients. A total of 1404 consecutive patients (52% women, mean age 57.5), with a diagnosis of IPMN from 1994 through 2017 at the University of Tokyo, Japan was carried out using a competing risk analysis, estimating cumulative incidence of pancreatic carcinoma overall and by carcinoma type.

Competing risks proportional hazards models to estimate subdistribution hazard ratios (SHRs), for incidences of carcinoma to differentiate IPMNderived and concomitant carcinomas, collection of genomic DNA from available paired samples of IPMNs and carcinomas and detected mutations in GNAS and KRAS by polymerase chain reaction and pyrosequencing was carried out.

During 9231 person-years of followup, 68 patients were identified with pancreatic carcinoma (38 patients with IPMN-derived carcinoma and 30 patients with concomitant PDACs); the overall incidence rates were 3.3%, 6.6% and 15% at 5, 10 and 15 years, respectively. Among 804 patients followed more than 5 years, overall cumulative incidence rates of pancreatic carcinoma were 3.5% at 10 years and 12% at 15 years from the initial diagnosis. The size of the IPMN and the diameter of the main pancreatic duct associated with incidence of IPMN-derived carcinoma (SHR 1.85 for a 10 mm increase in IPMN size and SHR 1.56 for a 1 mm increase in the main pancreatic duct diameter), but not with incidence of concomitant PDAC.

It was concluded in a large, long-term study of patients with branch-duct IPMNs, we found a 5-year incidence rate of pancreatic malignancy to be 3.3%, reaching 15% at 15 years after IPMN and diagnosis. There were heterogeneous risk factor profiles between IPMN-derived and concomitant carcinomas.

Oyama, H., Tada, M., Takagi, K., et al. “LongTerm Risk of Malignancy in Branch-Duct Intraductal Papillary Mucinous Neoplasms.” Gastroenterology 2020; Vol. 158, pp. 226-237.

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