Background/Purpose: The development of lymphomas is one of the most serious complications of SjS but the incidence, prevalence and estimated risk of lymphoma in primary SjS vary significantly worldwide. Meanwhile, studies from Taiwan and Spain, the estimated risk of thyroid cancer appears slightly increased in primary SjS compared with previous results. Although primary SjS is a very rare disease and many cases are required to determine the exact risk of malignancy in this condition, most epidemiological studies of primary SjS have been limited to a small number of cases such as case-control studies, leading to low-quality evidence. A large sample size with a significant number of cases is therefore required to analyse the risk of lymphoma and thyroid cancer in primary SjS. The aim of this study was to evaluate the incidence and risk of lymphoma and thyroid cancer in patients with primary Sjögren’s syndrome (SjS) employing a large-scale assessment based on the Korean National Health Insurance Service (NHIS) claims database.

Methods: Primary SjS was identified using the Korean NHIS medical claims database between 2007 and 2017. The case definition required more than one visit based on the Sjögren’s syndrome diagnostic code and the registration system for rare and incurable diseases. A 3-year washout period was applied in our study to exclude patients who were diagnosed before their information was entered into the national rare and incurable disease database. The presence of a connective tissue disease before the SjS diagnosis and within one year after the SjS diagnosis was ruled out in order to recruit primary SjS only. We included all admissions with a primary diagnosis of lymphoma and thyroid cancer.

Results: The primary SjS incidence was 1.88 cases/100,000 inhabitants. Female patients had a higher incidence than male patients, with a female-to-male ratio of 7.65:1. For primary SjS, the standardised incidence ratios for lymphoma and thyroid cancer were 4.66 (95% confidence interval [CI] 2.69–7.55) and 1.23 (95% CI 0.88–1.68), respectively. The lymphoma risk was 4.66-fold higher among the patients with primary SjS than in the general population. Compared with the general population, female patients with primary SjS had a 5.32-fold higher risk of developing lymphoma, while the male patients did not. Patients with primary SjS did not have a higher risk of developing thyroid cancer.

Conclusion: Primary SjS is associated with a higher risk of developing lymphoma. The lymphoma risk appears to have decreased compared with that in previous studies. Our study suggests that the risk of lymphoma or thyroid cancer with SjS is not higher than that reported in previous studies.

2019 ACR table_SjS

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-of-lymphoma-and-thyroid-cancer-in-primary-sjogrens-syndrome-measured-using-the-korean-health-insurance-claims-database/