Lymphoma and Sjögren Syndrome: A Common Overlapping Syndrome?

To the Editor:

We read with interest the research article entitled, “Bidirectional Relationship Between Primary Sjögren Syndrome and Non-Hodgkin Lymphoma: A Nationwide Population-based Study” by Wang, et al published in The Journal of Rheumatology.¹ The authors conducted research revealing that primary Sjögren syndrome (SS) and non-Hodgkin lymphoma (NHL) are bidirectionally associated with each other. This article was the first to point out that, contrary to previous studies, patients with NHL are also more likely to develop primary SS (pSS) than healthy individuals. We appreciate their findings and would like to make some contributions.

First, the diagnosis of SS can be classified into primary or secondary. We suggest that the authors exclude patients with secondary SS from their NHL cohort to avoid confounding by underlying diseases, such as systemic lupus erythematosus, rheumatoid arthritis, or other autoimmune diseases.

Second, the highest risk of this bidirectional relationship is within the first year after the diagnosis of the underlying diseases. We believe that a delayed diagnosis of SS could influence the result, since both diseases could be slowly progressing and may have subclinical stages.

Finally, pSS, with different clinical stages ranging from localized lymphocytic infiltration of specific organs to systemic involvement, has played a role in determining the relationship between lymphoma and autoimmune disease.² Also based on Taiwan’s National Health Insurance Research Database, the recent publication by Cai, et al revealed that treatment with conventional synthetic disease-modifying antirheumatic drugs does not correlate with the risk of developing neoplasms in patients with rheumatic diseases.³ Thus, the autoimmune diseases themselves affect carcinogenesis more than immunomodulators. We suggest that the authors¹ perform sensitivity tests or even conduct a new study to investigate the effect of disease severity of SS and lymphoma.

• © 2021 The Journal of Rheumatology