Increased cancer incidence in a Swedish cohort of patients with systemic lupus erythematosus

OBJECTIVE: To assess the risk of cancer in patients with systemic lupus erythematosus (SLE). METHODS: A population-based cohort of 5 715 hospitalised SLE patients was followed 1964-1995 through linkage of the Hospital Discharge Register to the National Swedish Cancer Register. RESULTS: In all, 443 malignancies occurred during the observation-period. The overall risk was increased by 25% (SIR= 1.25, CI 95% 1.14-1.37) and lymphomas constituted the major excess risk. The risk of non-Hodgkin's lymphoma (NHL) was nearly 3-fold increased (SIR = 2.86, CI 95% 1.96-4.04). There was also an increased risk of lung cancer (SIR= 1.73, CI 95% 1.25-2.32) and squamous cell skin cancer (SIR= 1.53, CI 95% 0.98-2.28), which was most pronounced at more than 15 years of follow-up. CONCLUSION: The major finding was a bimodal incidence pattern with an increased risk of lymphoma, mainly NHL, early during follow-up, but lung cancer and squamous skin cancer later on.