Bidirectional relationship between primary sjögren syndrome and non-hodgkin lymphoma: A nationwide taiwanese population-based study

Objective. Bidirectional relationships between some autoimmune diseases and non-Hodgkin lymphoma (NHL) may exist. We conducted this nationwide population-based study in Taiwan to investigate whether there is a bidirectional relationship between primary Sjögren syndrome (pSS) and NHL. Methods. Using the National Health Insurance Research Database of Taiwan, we identified 15,636 patients with new-onset pSS without previous cancer and 25,074 patients with new-onset NHL without previous pSS as 2 non-overlapping cohorts from 1998 to 2012, and followed them until 2013. Standardized incidence ratios (SIR) for NHL in the patients with pSS and SIR for pSS in the patients with NHL were compared with the general population. Results. Among the 15,636 patients with pSS, 741 developed cancers, including 51 with NHL. The highest SIR of specific cancer risk in patients with pSS was that for NHL (SIR 4.6, 95% CI 3.4–6.0). Among the 25,074 patients with NHL, 49 developed pSS; the SIR was also increased (SIR 3.2, 95% CI 2.4–4.2). The risk was highest within 1 year after the diagnosis of each disease. Conclusion. This nationwide population-based study is the first to report a bidirectional relationship between pSS and NHL. Our findings suggest being alert for patients with pSS or NHL who have early signs of the other disease in clinical care. The underlying mechanisms of the bidirectional relationship merit further investigation.