Objective: It has been discussed whether IgG4-related disease (IgG4-RD), including autoimmune pancreatitis (AIP), is associated with malignancy; however, the issue has not been clarified.
Methods: We analyzed 113 patients with IgG4-RD in whom malignancy was not diagnosed at the time of IgG4-RD onset and the follow-up period was longer than six months. A total of 95 patients had AIP. The mean follow-up period was 73 months. The incidence of the observed malignancies was compared with the expected incidence in an age- and sex-matched general Japanese population based on the Vital Statistics of Japan.
Results: There were 15 malignancies (lung cancer in five patients, pancreatic cancer in two patients, gastric cancer in two patients, bile duct cancer in one patient, renal cancer in one patient, breast cancer in one patient, tongue cancer in one patient, malignant melanoma in one patient and acute myeloid leukemia in one patient) in 14 patients during the follow-up period. The calculated standardized incidence rate of the total malignancies was not significant, that is, 1.04 (95% CI 0.57-1.75).
Conclusion: The incidence of total malignancies in IgG4-RD patients is similar to that observed in the general population. At present, it is reasonable to conclude that IgG4-RD is not associated with an increased incidence of total malignancies.