In Inflammatory Bowel Disease (IBD) patients, thiopurines promote carcinogenesis of Epstein-Barr Virus
(EBV)-related lymphomas, non-melanoma skin cancers and urinary tract cancers, while anti-TNF agents could promote
carcinogenesis of melanomas. Patients with IBD and previous cancer are at a higher risk of developing new or
recurrent cancer than IBD patients without a history of cancer, irrespective of the use of immunosuppressants. In
transplant recipients, the use of thiopurines is associated with a high rate of cancer recurrence, particularly within the
first two years following transplantation. In patients with chronic inflammatory disease, limited data suggest that no
dramatic incidence of cancer recurrence is associated with the use of thiopurines or anti-TNF agents. However, there is
a rationale for a two-year drug holiday from immunosuppressants after the diagnosis and treatment of the majority of
incident cancers, as often as possible. Extending the duration of the immunosuppressant drug holiday to 5 years in patients
with previous cancers associated with a high risk of recurrence in the post-transplant state should be considered.
The immunosuppressants that can be initiated or resumed after cancer treatment should be chosen according to the type
of the previous cancer. All individual decisions should be made on a case-by-case basis, together with the oncologist,
according to characteristics and expected evolution of the index cancer, expected impact of the immunosuppressants
on cancer evolution, and intrinsic severity of IBD, with its associated risks.