[Reynolds syndrome revealing a malignant thymoma]

[Autoimmune diseases and cancers. Part I: cancers complicating autoimmune diseases and their treatment]

The link between systemic disease and cancer is not fortuitous. An autoimmune disease can represent the starter for developing a non-Hodgkin lymphoma. This is particularly true for Sjögren's syndrome that is associated with the highest risk of lymphoma (odds ratio up to 44). Other systemic autoimmune diseases concerned are systemic lupus with an odds ratio of 4.5 and rheumatoid arthritis with an odds ratio of 2 to 3. It is now well established that high inflammatory activity, rather than immunosuppressive treatment, is the major risk determinant. The association between solid cancer and autoimmune systemic disease is uncommon and concerns in particular scleroderma and lung cancer. Concerning biotherapy-induced cancers, there is no demonstrated increased risk with anti-TNFα (except for cutaneous carcinoma and maybe melanoma) or with tocilizumab and abatacept even if studies with longer follow-up are needed at least for these two last drugs.