Lymphoma and other malignancies in primary Sjögren’s syndrome: a cohort study on cancer incidence and lymphoma predictors
- Department of Rheumatology, Department of Laboratory Medicine and Department of Pathology, Malmö University Hospital, Lund University, Lund, Sweden
- Correspondence to:
Dr E Theander
Department of Rheumatology, Malmö University Hospital, S-20502 Malmö, Sweden;
- Accepted 24 October 2005
- Published Online First 10 November 2005
Objectives: To assess the risk of lymphoproliferative disease or other malignancy (standardised incidence ratios (SIRs)), in patients with primary Sjögren’s syndrome according to the American-European Consensus Criteria (AECC), compared with patients with sicca syndrome (non-AECC) and the background population. To identify predictors of malignancy and describe lymphoma types and survival probabilities.
Methods: A linked register study using information from the Malmö Primary SS Register, Swedish Cancer Register, and Cause-of-Death Register for calculation of SIRs was carried out. Detected lymphomas were reclassified according to the WHO classification. Cox regression analysis was used to study the predictive value of clinical, laboratory, and histological findings at the time of diagnosis.
Results: 507 patients with a median follow up of 8 years (range 1 month to 19 years) were included. SIRs (95% confidence interval (CI)) for malignancies in total and for non-Hodgkin’s lymphomas (NHL) were 1.42 (0.98 to 2.00) and 15.57 (7.77 to 27.85), respectively, in those fulfilling the AECC (n = 286). In non-AECC sicca patients (n = 221) SIR for malignancy of any kind was 0.77 (0.41 to 1.32); no lymphoproliferative neoplasms were detected. Significant predictors of lymphoproliferative disease were purpura/skin vasculitis (hazard ratio (HR) = 4.64, 95% CI 1.13 to 16.45), low complement factor C3 (HR = 6.18, 95% CI 1.57 to 24.22), low C4 (HR = 9.49, 95% CI 1.94 to 46.54), CD4+ T lymphocytopenia (HR = 8.14, 95% CI 2.10 to 31.53), and a low CD4+/CD8+ T cell ratio ⩽0.8 (HR = 10.92, 95% CI 2.80 to 41.83). 7/12 (58%) NHLs were diffuse large B cell lymphomas.
Conclusion: A 16-fold increased risk for development of NHL was found. CD4+ T lymphocytopenia is an additional strong risk factor for developing lymphoma.
- AECC, American-European Consensus Criteria, ANA, antinuclear antibody
- CI, confidence interval
- DLBC, diffuse large B cell
- HR, hazards ratio
- NHL, non-Hodgkin’s lymphoma
- pSS, primary Sjögren’s syndrome
- RA, rheumatoid arthritis
- RF, rheumatoid factor
- SIR, standardised incidence ratio
Published Online First 10 November 2005
Competing interests: None.
The study was approved by the ethics committee at Lund University.