Association between autoantibodies in systemic sclerosis and cancer in a national registry.

Objective: A close temporal relationship between SSc onset and cancer has been reported in anti-RNA polymerase III-positive patients. We investigated the association between cancer and other SSc autoantibodies in a national SSc registry.

Methods: SSc patients enrolled in the Canadian Scleroderma Research Group registry from 2004 to 2019 were characterized according to autoantibodies to centromere, topoisomerase I/Scl70, RNA polymerase III, fibrillarin, Th/To (hPOP1), PM/Scl, Ku, NOR90, Ro52/TRIM21 and U1RNP. Logistic regression was used to examine the association between a close cancer-SSc interval and autoantibody status, adjusted for age, sex, race and smoking history.

Results: Of 1698 SSc patients, 1481 (87%) had available autoantibody data. Cancer was diagnosed within 2, 3 and 5 years of the first non-Raynaud manifestation in 1.3%, 2.1% and 3.5% of patients. The most frequent cancers diagnosed within 2 years were breast (33%), gynaecological (19%) and haematological (14%) cancers. The risk of cancer within 2 years was increased among anti-topoisomerase I [odds ratio (OR) 3.43, 95% CI: 1.04, 10.05] and anti-U1-RNP-positive patients (OR 5.54, 95% CI: 1.16, 20.40), but not with anti-RNA polymerase III. None of the anti-fibrillarin, Th/To, PM/Scl, Ku and NOR90-positive patients had cancer within 2 years. Patients with anti-centromere or none of the tested autoantibodies had numerically lower risks of developing cancer within two years.

Conclusion: Synchronous cancer was rare in this large cohort of predominantly female and White SSc patients. The risk of cancer within 2 years was increased among anti-topoisomerase I and anti-U1-RNP-positive patients. Screening strategies guided by autoantibodies require further careful consideration.