Study links widely-used drug azathioprine to skin cancers. A drug used to treat inflammatory bowel disease, arthritis and vasculitis as well as to prevent organ rejection in transplant patients has been identified as an important contributor to skin cancer development. The research identified a `strong case for an association' between the drug azathioprine and the mutational signature found in cases of cutaneous squamous cell carcinoma (CSCC), a common form of skin cancer. Source 7q.