- Women with breast cancer appear to have lower risks for systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren's syndrome.
- Risk for dermatomyositis /polymyositis was not affected.
Why this matters
- First study of its kind suggests that impaired T-cell environment of breast cancer does not increase risk for major autoimmune diseases.
- Population-based retrospective cohort (2007-2013) from the Taiwanese National Health Insurance Research Database.
- Primary endpoint: incidence of major autoimmune diseases in women with breast cancer (n=54,311) vs noncancer control individuals (n=217,244) matched by age and the year of index date of major autoimmune diseases.
- Funding: Taichung Veterans General Hospital, Taiwan.
- Incidence rates per 100,000 women-years for women with vs without cancer:
- SLE: 2.3 vs 10.0 (aHR, 0.04; 95% CI, 0.01-0.24).
- RA: 19.3 vs 42.7 (aHR, 0.03; 95% CI, 0.02-0.04).
- Sjögren's syndrome: 20.5 vs 38.2 (aHR, 0.21; 95% CI, 0.09-0.48).
- No difference was observed between groups in incidence of dermatomyositis/polymyositis (2.3 vs 1.7 per 100,000 women-years; aHR, 0.37; 95% CI, 0.08-1.80).
- Retrospective, observational design.