Objectives: The risk of pancreatic and extrapancreatic cancer in autoimmune pancreatitis (AIP) has not been systematically evaluated. We compared the risk of malignancy in AIP patients and matched control subjects.
Methods: We identified 116 subjects with AIP from a prospectively maintained database. From patients evaluated in primary care clinics, we selected 3 control subjects for each AIP patient matched on age, registration date, and sex (n = 344) . Risk for developing cancer after the index date was compared using a stratified Cox model.
Results: The proportion of patients diagnosed with cancer before AIP diagnosis (10.3%) was lower than that in the matched control subjects (17.4%). After a median follow-up of over 3 years, the risk of developing cancer after the index date was similar in AIP and control subjects (hazard ratio, 0.64; 95% confidence interval, 0.27-1.51). The 3 most commonly diagnosed malignancies in the AIP group were prostate cancer, lymphoma, and bladder cancer.
Conclusions: Cancer risk before and after diagnosis of AIP is similar to that of control subjects. Specifically, there is no increased risk of cancer immediately preceding or following AIP diagnosis. Additional follow-up is needed to determine if there is a cumulative increase in cancer risk in AIP.