TNF and inflammatory bowel disease: Although in Western countries, several studies have reported an approximately four-fold higher risk of lymphoma in IBD patients treated with thiopurines, some series in Asia have not found an increased risk of lymphoma in IBD patients treated with thiopurines, with or without an anti-TNF agent, maybe because of a lower baseline incidence of lymphomas, a lower standard dose of thiopurines used in countries like Japan compared with Western countries, and/or genetic factors [12,13].