Abstract
BACKGROUND: Patients with many types of autoimmune diseases (AIDs) are at an increased risk of cancer, which may depend on underlying dysregulation of the immune system or treatment. We systematically analyzed myeloma risk and survival in patients diagnosed with 33 different AIDs. METHODS: Data on patients with AIDs were retrieved from the Swedish Hospital Discharge Register and were linked to myeloma diagnoses from the Cancer Registry. Standardized incidence ratios (SIR) and hazard ratios (HRs) were calculated for subsequent myeloma between 1964 and 2008. RESULTS: Among patients with the 33 AIDs analyzed, 457 cases of myeloma were diagnosed. The overall SIR for myeloma was 1.12 and the overall HR was 0.92 and non-significant. SIRs for myeloma were significantly increased after ankylosing spondylitis (2.02) and systemic sclerosis (2.63). Only the HR for myeloma after rheumatic fever (5.27) was significantly increased. The SIR for myeloma before age 60 years was 1.45; the SIR for myeloma was only increased in the period 1964-1990 (1.31) and not later (1.04). Only the SIR for myeloma after ankylosing spondylitis was increased in the period 1991-2008 (2.09); the HRs for myeloma were increased after polymyositis/dermatomyositis (6.44) and rheumatic fever (4.43) but there were only three deaths of myeloma after these AIDs. CONCLUSIONS: The present data showed an increase in myeloma SIR after two AIDs, ankylosing spondylitis and systemic sclerosis, and in HR after rheumatic fever. The overall myeloma risk after any AID was no longer increased in the latter follow-up period of 1991 through 2008.