Simple SummaryWith the increase in life-expectancy and the aging population, patients with inflammatory bowel disease are being exposed to immunomodulating drugs for longer periods. This, as well as the already recognized higher risk of some cancers in these patients when compared to the general population, makes the challenge of managing a patient with inflammatory bowel disease and current or past cancer more common. As large prospective studies are awaited, we summarize the available data on cancer risk in inflammatory bowel disease patients, the risk of cancer recurrence with immunomodulating therapy, the effects of cancer treatment on inflammatory bowel disease, and current recommendations on how to balance the risks and benefits of different treatments in these patients.AbstractInflammatory bowel disease (IBD) is a chronic disease for which medical treatment with immunomodulating drugs is increasingly used earlier to prevent disability. Additionally, cancer occurrence in IBD patients is increased for several reasons, either IBD-related or therapy-associated. Doctors are therefore facing the challenge of managing patients with IBD and a past or current malignancy and the need to balance the risk of cancer recurrence associated with immunosuppressive drugs with the potential worsening of IBD activity if they are withdrawn. This review aims to explore the features of different subtypes of cancer occurring in IBD patients to present current evidence on malignancy recurrence risk associated with IBD medical therapy along with the effects of cancer treatment in IBD and finally to discuss current recommendations on the management of these patients. Due to sparse data, a case-by-case multidisciplinary discussion is advised, including inputs from the gastroenterologist, oncologist, and patient.