Among individuals with scleroderma, autoantibody specificity and disease subtype are biologically meaningful filters that may help inform cancer risk stratification in this patient population, with respect both to overall cancer and to specific types of cancer, according to the results of an observational cohort study of patients from the Johns Hopkins Scleroderma Center, published in the Annals of the Rheumatic Diseases.
The investigators sought to examine cancer risk in distinct serologic and phenotypic scleroderma subsets vs estimates in the general population. They calculated overall and site-specific cancer incidence in distinct autoantibody and scleroderma phenotypic subsets and compared these with the Surveillance, Epidemiology and End Results (SEER) registry, which is a representative sample of the US population.
A total of 2383 patients with scleroderma, yielding 37,686 person-years, were evaluated. Overall, 8.6% of the patients had received a cancer diagnosis. Within 3 years of scleroderma onset, the risk for cancer was increased in patients with RNA polymerase III autoantibodies (standardized incidence ratio [SIR], 2.84; 95% CI, 1.89-4.10) and in patients who lacked centromere, topoisomerase-1, and pol antibodies (SIR, 1.83; 95% CI, 1.10-2.86).
In participants with RNA polymerase III autoantibodies, cancer-specific risk may vary according to scleroderma subtype: Participants with diffuse scleroderma had an increased risk for breast cancer, whereas those with limited scleroderma had a high risk for lung cancer. However, patients with anticentromere antibodies had a lower risk for cancer during study follow-up (SIR, 0.59; 95% CI, 0.44-0.76).
The investigators concluded that future research is warranted to assess the value of targeted cancer screening strategies in patients with scleroderma. Studying the mechanistic basis for differences in cancer risk across scleroderma subtypes is likely to improve understanding of the disease, autoimmunity, and cancer immunity.
Igusa T, Hummers LK, Visvanathan K, et al. Autoantibodies and scleroderma phenotype define subgroups at high-risk and low-risk for cancer [published online April 20, 2018]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2018-212999