title: Review article: the risks of malignancy from either immunosuppression or diagnostic radiation in inflammatory bowel disease.
abstract: Inflammatory bowel disease is associated with an increased risk of gastrointestinal malignancy. There has been concern that either diagnostic medical radiation and long-term drug therapy--particularly immunosuppression--might contribute to this increased cancer risk. For the major drug groups (5-aminosalicylates, steroids and immunosuppressants) data are scant but broadly reassuring. Only azathioprine (including 6-mercaptopurine) has been investigated at all carefully. Short- to medium-term therapy probably poses a very slightly increased risk of malignancy which is easily accepted given the current limitation of this agent to second-line use. Continuous therapy for more than two years is much less well documented, and caution should be maintained. A hypothetical model based on data from occupational radiation exposure has been constructed; this permits reasonable confidence that the medical use of ionising radiation contributes a negligibly increased risk of malignancy overall, and is particularly unlikely to add significantly to the incidence of gastrointestinal malignancy.
authors.affiliation: St Mark's Hospital, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Forbes
authors.forename: N G
authors.initials: NG
authors.lastname: Reading
mesh_terms: D001379:Azathioprine / Q000009:adverse effects; D003524:Cyclosporins / Q000009:adverse effects; D005770:Gastrointestinal Neoplasms / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D011859:Radiography / Q000009:adverse effects; D012307:Risk Factors; D012459:Salicylates / Q000009:adverse effects; D013256:Steroids / Q000009:adverse effects
chemical_list: D003524:Cyclosporins; D007166:Immunosuppressive Agents; D012459:Salicylates; D013256:Steroids; D001379:Azathioprine