Abstract
BackgroundThe purpose of this study is to characterize the risk of cancer in a large cohort of patients with primary Sjögren syndrome (SjS).MethodsWe had analyzed the development of cancer in 1300 consecutive patients fulfilling the 2002 SjS classification criteria. The baseline clinical and immunological characteristics and systemic activity (ESSDAI scores) were assessed at diagnosis as predictors of cancer using Cox proportional hazards regression analysis adjusted for age at diagnosis and gender. The sex-and age-specific standardized incidence ratios (SIR) of cancer were estimated from 2012 Spanish mortality data.ResultsAfter a mean follow-up of 91 months, 127 (9.8%) patients developed 133 cancers. The most frequent type of cancer was B-cell lymphoma (including 27 MALT and 19 non-MALT B-cell lymphomas). Systemic activity at diagnosis of primary SjS correlated with the risk of hematological neoplasia and cryoglobulins with a high risk of either B-cell or non-B-cell lymphoma subtypes. Patients with cytopenias had a high risk of non-MALT B-cell and non-B-cell cancer, while those with low C3 levels had a high risk of MALT lymphomas and those with monoclonal gammopathy and low C4 levels had a high risk of non-MALT lymphomas. The estimated SIR for solid cancer was 1.13 and 11.02 for hematological cancer. SIRs for specific cancers were 36.17 for multiple myeloma and immunoproliferative diseases, 19.41 for Hodgkin lymphoma, 6.04 for other non-Hodgkin lymphomas, 5.17 for thyroid cancer, 4.81 for cancers of the lip and oral cavity, and 2.53 for stomach cancer.ConclusionsOne third of cancers developed by patients with primary SjS are B-cell lymphomas. The prognostic factors identified at SjS diagnosis differed according to the subtype of B-cell lymphoma developed. Primary SjS is also associated with the development of some non-hematological cancers (thyroid, oral cavity, and stomach).
Highlights
The purpose of this study is to characterize the risk of cancer in a large cohort of patients with primary Sjögren syndrome (SjS)
We found a higher risk of developing hematological cancer in patients receiving corticosteroids (HR 2.67; p < 0.001) or an immunosuppressive agent (HR 2.83; p < 0.001), the multivariate analysis adjusted for the main prognostic factors identified showed only non-significant differences
With respect to hematological cancers, we had to adapt our classification of hematological cancer to the four categories of hematological cancer used in the GLOBOCAN database; the correspondence between the two classifications is shown in Additional file 1: Table S7
Summary
The purpose of this study is to characterize the risk of cancer in a large cohort of patients with primary Sjögren syndrome (SjS). Since 1978 [2], SjS has been closely associated with an enhanced risk of lymphoma, one of the most severe complications a patient may develop. Primary SjS patients have a 10–44-fold greater risk of lymphoma than healthy individuals, higher than that reported for systemic lupus erythematosus (sevenfold) and rheumatoid arthritis (fourfold) [3]. The lymphomagenesis hypothesis in primary SjS suggests a key role for the continued stimulation of B cells in the exocrine glands and organs containing mucosa-associated lymphoid tissue (MALT); in some patients, this autoimmune process is further altered by a combination of prooncogenic factors that promote abnormal increases in Bcell survival, putting the patient at high risk of a malignant B-cell transformation [6]
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