Cancer and Systemic Lupus Erythematosus

KEY POINTS• Systemic lupus erythematosus (SLE) is associated with a small overall increased cancer risk compared to the general population.This includes a 4-fold increased risk of non-Hodgkin lymphoma (NHL), but a decreased risk of other cancers (such as breast cancer).• The pathophysiology underlying the increased risk of hematologic cancer is not fully understood, but many potential mechanisms have been proposed, including dysfunction of the tumor necrosis factor (TNF) and other pathways.• A decreased risk of breast, ovarian and endometrial cancer might be driven by hormonal factors or lupus-related antibodies, but these links have not been proven.• Cyclophosphamide may be a risk factor for hematological cancers in SLE, but this does not entirely explain the altered cancer risk profile in SLE.Exposure to hydroxychloroquine may be inversely related to breast and possibly other cancers.• Recent evidence suggests that higher disease activity itself may be associated with lymphoma risk in SLE, but not with non-hematologic malignancies.• Cancer preventive methods such as smoking cessation and regular cancer screening remain important in the SLE population.