Background: Treatment of inflammatory bowel disease (IBD) in patients with prior malignancy is challenging because therapeutic immunosuppression required for controlling IBD activity may increase the risk of cancer recurrence. Key Messages: Contrary to the observations in the post-transplant population, retrospective observational studies of IBD patients with prior malignancy have not demonstrated that immunosuppressive drugs increased significantly the risk of new or recurrent cancer. However, these studies are highly biased and do not permit the use of these drugs. Factors like the time since treatment completion, severity, and subtype of prior cancer should be weighed along with the current IBD activity before choosing the best therapeutic strategy. In practice, most cases of prior cancer require a delay of at least 2 years before starting or resuming immunosuppressants, including anti-TNF agents. This delay should be extended to 5 years in cancer with a high risk of recurrence including cancer of the urinary tract, gastrointestinal cancer, leukemias, and multiple myeloma. A special attention should be paid to cancers with a high risk of late metastasis (breast, melanoma, renal cell carcinoma). Enteral nutrition, Budesonide, mesalamine, and limited intestinal resection should be considered following the completion of cancer treatment and prior to the safe initiation of immunosuppressive treatment for IBD. Thiopurines should be avoided in case of prior Epstein-Barr virus-related lymphoma, HPV-related carcinomas, and cancer of the urinary tract. Methotrexate and anti-TNF agents seem to be safe except for the risk of recurrent melanoma for the latter. Conclusion: IBD patients with prior malignancy should benefit from individual decisions made on a case-by-case basis.
Low prevalence of anti-xenobiotic antibodies among the occupationally exposed individuals is associated with a high risk of cancer
