Evaluation of cancer-associated myositis and scleroderma autoantibodies in breast cancer patients without rheumatic disease

Objective. Systemic sclerosis (scleroderma) and dermatomyositis are two prototypic autoimmune diseases that are strongly associated with malignancy. While specific autoantibodies in these diseases are markers of an increased risk of cancer at scleroderma and dermatomyositis onset, it is not known whether these autoantibodies are biomarkers of cancer risk in patients without rheumatic disease. Methods. In a matched case-control study of women without rheumatic disease, identified from a familial breast cancer cohort, 50 breast cancer cases and 50 controls were assayed for 3 autoantibodies that are known markers of cancer-associated scleroderma and dermatomyositis: anti-RNA polymerase III, anti-NXP2, and anti-TIF1γ. Results. No subject had moderate or strong autoantibody positivity. Eleven women were borderline positive for at least one autoantibody. The prevalence of borderline autoantibody positivity did not differ between cases and controls. Conclusion. Our results suggest that scleroderma and dermatomyositis autoantibodies are cancer biomarkers only in patients with clinical manifestations of specific rheumatic diseases and are unlikely to improve risk stratification for cancer in the general population. However, prospective studies are needed to examine whether scleroderma and dermatomyositis autoantibodies are markers of malignancy in other cancer types.