Analysis of 303 Ro/SS-A antibody-positive patients: is this antibody a possible marker for malignancy?

BACKGROUND: The risk of cancer in patients with autoimmune diseases has been investigated in several studies. Ro/SS-A antibodies are frequent and specific autoantibodies among patients with various autoimmune diseases. OBJECTIVES: To assess the risk of cancer in individuals with positive Ro/SS-A antibodies and to analyse their clinical and laboratory characteristics. METHODS: Consecutive patients (n = 303) with Ro/SS-A antibody positivity were collected during 11 years in our outpatient clinic for autoimmune diseases and were retrospectively analysed. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for all cancers were calculated. In addition, we identified further clinical and laboratory characteristics of Ro/SS-A antibody-positive patients indicating the development or existence of a malignancy. RESULTS: Fifty (16·5%) patients were diagnosed with malignancies. Ro/SS-A antibody was strongly associated with malignant diseases (SIR 2·6, 95% CI 1·9-6·1), particularly melanoma (SIR 33·3, 95% CI 5·2-188·6), T-cell lymphoma (SIR 16·7, 95% CI 2·9-128·9), non-Hodgkin lymphoma (SIR 10·6, 95% CI 1·5-78·9) and breast carcinoma (SIR 4·98, 95% CI 1·3-28·3). Logistic regression modelling revealed that Ro/SS-A antibody-positive patients aged 55 years or older, presenting with fever, anaemia and cutaneous lupus erythematosus, have a greater probability of developing cancer and are considered high-risk patients, as compared with Ro/SS-A antibody-positive patients with none of the mentioned clinical criteria. CONCLUSIONS: In our cohort of Ro/SS-A antibody-positive patients, an overall increased risk of malignancy was noticed. Regular screening tests including imaging and laboratory values are justified in Ro/SS-A antibody-positive patients who exhibit the mentioned clinical criteria.