Malignancy and autoimmunity : causally or casually related?

Coexistent malignancy and autoimmune rheumatic disease requires the physician to explore a causal link. Rheumatic manifestations mimicking autoimmune diseases can precede, accompany or follow the onset of neoplastic disease. Identified links include shared environmental factors such as smoking with rheumatoid arthritis and lung cancer, and a common disease such as inflammatory bowel disease with spondyloarthritis and colon cancer. Long-term and often severe immune stimulus of autoimmune disease has been linked to malignancy of the immune system, and paradoxically, long-term suppression of the immune response as exemplified in organ transplantation, is also linked to risk of subsequent malignancy.