Malignancy in systemic lupus erythematosus: what have we learned?

What have we learnt about cancer risk in systemic lupus erythematosus (SLE) over the past decade? One important lesson is that data do confirm a slightly increased risk in SLE for all cancers combined, compared to that in the general population. However, it is clear that this is largely driven by an increased risk for haematological malignancies, particularly non-Hodgkin's lymphoma (NHL), although Hodgkin's lymphoma may be increased as well. In addition, there is evidence for a moderately increased risk of lung cancer, and possibly for rarer cancer types such as hepatobiliary and vulvar/vaginal malignancies. Unfortunately, the most clinically relevant question – the mechanism underlying the association between cancer and SLE – remains largely unanswered. Key issues remaining relate to the links between cancer risk, SLE disease activity, and medication exposures. Much of the recent data suggest that disease-related factors may be at least as important as medication exposures for certain cancers, such as NHL. The independent effects of drug exposures versus disease activity in mediating cancer risk in SLE remain unknown. Work is in progress to further elucidate these important issues. Meanwhile, there is good evidence that cervical dysplasia is increased in women with SLE. This may be mediated by decreased clearance of the human papilloma virus, which some suggest is an innate characteristic of SLE patients. However, an increased risk of cervical dysplasia is also associated with immunosuppressive medication exposures, particularly cyclophosphamide. For these reasons, it is important that women with SLE follow established guidelines for cervical cancer screening.

Keywords: malignancy, cancer, systemic lupus erythematosus, SLE, lymphoma, NHL