Occurrence of neoplasia in patients with rheumatoid arthritis enrolled in a DMARD Registry. Rheumatoid Arthritis Azathioprine Registry Steering Committee.

The Rheumatoid Arthritis Azathioprine Registry (RAAR) was established in 1982 to examine the safety of azathioprine (AZA) and other disease modifying agents (DMARD) in the treatment of RA. In yearly followup over the past 7 years, 20 malignant conditions have been reported in 530 DMARD treated adult patients with RA. Incidence density ratios (IDR) and standardized morbidity ratios (SMR) were calculated to assess cancer risk. For all cancers the SMR was 1.52 (95% CI 0.90-2.60). For men the SMR was 1.71 (95% CI 0.84-3.52); for women the SMR was 1.52 (95% CI 0.89-2.60). Adjusted for age, the IDR was highest in the 70-79-year-old study population (3.41). The age and sex adjusted SMR for lymphoproliferative disorders and myeloma was 8.05 (95% CI 3.30-20.81). The SMR for lung cancer (n = 6) was also increased (3.37; 95% CI 1.58-7.34). Compared with the general population, patients with RA requiring DMARD therapy may be at increased risk of malignancy, particularly lymphoproliferative disorders. The RAAR is an important prospective technique which will ultimately permit assessment of neoplasia risk by type and duration of DMARD therapy.