Objective: To estimate the risk of malignancy in a cohort of patients with systemic lupus erythematosus (SLE) from a university medical center.
Methods: The cohort consisted of patients with lupus who were residents of Allegheny County and who were seen at the University of Pittsburgh, 1981-91. Cases of cancer were identified by a postal survey and review of medical records. The expected number of malignancies in the lupus cohort were estimated from age, sex, and race adjusted census and cancer incidence data from Allegheny County. Standardized incidence ratios and 95% confidence intervals for all cancers were calculated.
Results: Six (2.7%) malignancies were observed in the 219 lupus patients from Allegheny County during the observation interval (1981-91) and after the first visit at the University of Pittsburgh. The expected number of malignancies was 4.42. The standardized incidence ratio for cancer in the lupus cohort from Allegheny County was 1.36 (95% confidence interval 0.50-2.96). The frequency of malignancy was not increased in the small number of patients who had received immunosuppressive drugs before the diagnosis of cancer. Non-Hodgkin's lymphoma occurred in one patient, who also had Sjögren's syndrome, and in one patient before entry into this study who was treated with FK-506 following renal transplant. No bladder cancers were observed during the study interval.
Conclusion: The overall frequency of malignancy was not increased in this medical center cohort of patients with lupus during a mean followup interval of 5.2 yrs. Longterm followup and a multicenter effort is needed to refine risk estimates of cancer in patients with lupus.