Connective tissue diseases (CTDs) are a group of chronic and disabling diseases that involve inappropriate or excessive immune responses. They include a wide variety of illnesses such as rheumatoid arthritis (RA), systemic sclerosis (SSc), systemic lupus
erythematosus (SLE) and Sjo¨gren’s syndrome (SS)
Autoimmune diseases are characterized by the irregular functioning of the immune system that leads to the loss of tolerance to self-antigens. The underlying nature of autoimmune diseases has
led to speculation that the risk of malignancy might be higher or lower in patients with such diseases.