Relationship between autoimmune pancreatitis and pancreatic cancer: a single-center experience

Ordinary chronic pancreatitis (CP), such as alcoholic CP, is well established to have the increased risk for pancreatic cancer (PaC), nevertheless an association between autoimmune pancreatitis (AIP) and PaC is still unknown. The aims of this study are to examine the frequency of patients who developed PaC during follow-up after being diagnosed with type 1 AIP and to compare the incidence rate of PaC between patients with type 1 AIP and CP.

Sixty-three patients with type 1 AIP and 41 patients with CP were enrolled. We examined development of PaC during follow-up from their clinical records.

The mean follow-up period was 62.4 months in AIP group and 49.2 months in CP group. The occurrence of PaC was observed in 3 patients with AIP during the mean follow-up period of 94.7 months (range, 31-186), whereas a single CP patient developed PaC 38 months after CP diagnosis. The incident rate of PaC during follow-up was comparable between the 2 groups [4.8% (3/63) in type 1 AIP group vs. 2.4% (1/41) in CP group]. In all of 3 AIP patients who developed accompanying PaC, the clinical remission of AIP was achieved with maintenance steroid therapy, when tumors were discovered. In the histological examination of one surgical patient with PaC, lymphoplasmacytic infiltration in storiform fibrosis with abundant IgG4-positive cell infiltration was observed around the PaC area.

Similar to patients with ordinary CP, surveillance for development of PaC is needed at regular interval during follow-up in AIP patients.