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/SSA 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.