Yusuke Kurita, MD, PhD1, Atsushi Nakajima, MD, PhD1, Kensuke Kubota, MD, PhD1

1Department of Gastroenterology and Hepatology, Yokohama City University Hospital, Yokohama, Japan

Background/Aims: The potential risk for cancer in patients with immunoglobulin 4-related sclerosing cholangitis (IgG4-SC) is unclear. The present study aimed to evaluate the incidence of cancer in patients with IgG4-SC.

Methods: We retrospectively collected clinical data for 121 patients diagnosed with IgG4-SC from 7 hospitals. We calculated the standardized incidence ratio (SIR) of cancer in IgG4-SC patients based on the national cancer rates. The SIR of pancreatic cancer and bile duct cancer and that of the period after the diagnosis of IgG4-SC were also calculated.

Results: The mean follow-up period was 6.4 years, with 121 IgG4-SC patients. During the follow-up period, 26 patients had cancer, and 29 cancers were diagnosed. Six pancreatic and three bile duct cancer cases were diagnosed. The SIR of cancer after the diagnosis of IgG4-SC was 1.90 (95 % confidence interval [CI] 1.67-2.21). The SIR of pancreatic cancer was 10.30 (95 % CI 9.05-11.94), while the SIR of bile duct cancer was 8.88 (95 % CI 7.81-10.30). The SIR of cancer in <1 year, 1-5 years, and > 5 years after diagnosis of IgG4-SC were 2.58 (95 % CI 2.53-2.64), 1.01 (95 % CI 0.91-1.12), and 2.44 (95 % CI 1.92-3.37), respectively.

Conclusion: IgG4-SC patients have a high risk of cancer. IgG4-SC may be associated with the development of pancreatic and bile duct cancer. The risk of cancer was high less <1 year and >5 years after diagnosis of IgG4-SC. Therefore, IgG4-SC patients may require careful long-term follow-up.

Keywords: IgG4-SC, inflammation; malignancy, pancreatic cancer, bile duct cancer