Standardized incidence ratios and risk factors for cancer in patients with systemic sclerosis: Data from the Spanish...

Patients with systemic sclerosis (SSc) are at increased risk of cancer, a growing cause of non-SSc-related death among these patients. We analyzed the increased cancer risk among Spanish patients with SSc using standardized incidence ratios (SIRs) and identified independent cancer risk factors in this population.

Spanish Scleroderma Registry data were analyzed to determine the demographic characteristics of patients with SSc, and logistic regression was used to identify cancer risk factors. SIRs with 95% confidence intervals (CIs) relative to the general Spanish population were calculated.

Of 1930 patients with SSc, 206 had cancer, most commonly breast, lung, hematological, and colorectal cancers. Patients with SSc had increased risks of overall cancer (SIR 1.48, 95% CI 1.36-1.60; P < 0.001), and of lung (SIR 2.22, 95% CI 1.77-2.73; P < 0.001), breast (SIR 1.31, 95% CI 1.10-1.54; P = 0.003), and hematological (SIR 2.03, 95% CI 1.52-2.62; P < 0.001) cancers. Cancer was associated with older age at SSc onset (odds ratio [OR] 1.22, 95% CI 1.01-1.03; P < 0.001), the presence of primary biliary cholangitis (OR 2.35, 95% CI 1.18-4.68; P = 0.015) and forced vital capacity <70% (OR 1.8, 95% CI 1.24-2.70; P = 0.002). The presence of anticentromere antibodies lowered the risk of cancer (OR 0.66, 95% CI 0.45-0.97; P = 0.036).

Spanish patients with SSc had an increased cancer risk compared with the general population. Some characteristics, including specific autoantibodies, may be related to this increased risk.