Background IgG4-related disease (IgG4-RD) is a fibroinflammatory disease of unclear etiology1. Some studies suggest that IgG4-RD predisposes patients to malignancy or is a forme fruste of cancer2, but we have frequently observed IgG4-RD patients with a history of malignancy preceding the clinical onset of IgG4-RD.
Objectives We sought to determine whether a history of malignancy was more common among patients at the onset of IgG4-RD compared to controls.
Methods We identified IgG4-RD patients with a history of invasive malignancy from a well-defined cohort of 125 patients and compared their malignancy history to those of two reference groups. First, we calculated a standardized prevalence ratio against general US population estimates from the Surveillance, Epidemiology, and End Results (SEER) database. Second, we identified up to five age- and gender-matched controls for each case and calculated the odds of malignancy among those with IgG4-RD compared to controls using conditional logistic regression.
Results The mean age at IgG4-RD onset was 50.3±14.9 years and 61% of the patients were male. Twenty (16%) had been diagnosed with 21 malignancies before the diagnosis of IgG4-RD. The observed prevalence of malignancy in this cohort was 2.5 times higher (95% CI:1.1–3.6) than expected compared to the SEER database. Compared with matched controls, a history of malignancy was more than three-fold higher in IgG4-RD (OR 3.1;95% CI:1.6–6.2).
Conclusions Our findings suggest that malignancy is associated with the subsequent development of IgG4-RD in a subset of patients with IgG4-RD. Potential explanations include shared risk factors for both IgG4-RD and cancer, the triggering by cancer of autoantigen expression leading to IgG4-RD, and an increased risk of IgG4-RD resulting from cancer treatment.
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Hart PA, Law RJ, Dierkhising RA, Smyrk TC, Takahashi N, Chari ST. Risk of cancer in autoimmune pancreatitis: A case-control study and review of the literature. Pancreas. 2014;43(3):417–421.
Disclosure of Interest None declared