5-Aminosalicylic Acid Chemoprevention in Inflammatory Bowel Diseases: Is It Necessary in the Age of Biologics and Small Molecules?

Background: Due to the increased incidence of colorectal cancer in inflammatory bowel diseases (IBDs), the value of chemoprevention for this patient group has been repeatedly debated in the past decade. This review describes available evidence and the current recommendations for chemoprevention in national and international guidelines IBD guidelines. Summary: 5-Aminosalicylic acid (5-ASA) compounds are the preferred therapeutic option for mild to moderate ulcerative colitis (UC). Aside from the known anti-inflammatory effects, their chemopreventive abilities have been described in vitro and in vivo. Pooling the increasing number of retrospective and population-based clinical studies over the last 15 years, 7 consecutive meta-analyses revealed partially conflicting results for the chemopreventive efficacy of 5-ASA, and thus, not all IBD guidelines currently recommend chemoprevention with mesalamine compounds. Accumulating evidence for decreasing the colorectal cancer (CRC) risk in support of thiopurines more recently shows a protective effect. This effect seems solely mediated by control of intestinal inflammation since, for this drug class, another mechanistic interference in IBD-associated CRC pathogenesis is not known. The results regarding chemopreventive efficacy for ursodeoxycholic acid or folic acid are equivocal, and the use of these medications to prevent CRC is not firmly established. Like UC, the risk of CRC is also significantly increased in patients with Crohn’s disease (CD), especially Crohn’s colitis. However, no published studies exclusively assess the effects of surveillance on the early detection of cancer or CRC chemoprevention in CD patients. In meta-analyses, which predominantly included UC patients, 5-ASA or thiopurines were not beneficial in small CD subgroups. The level of evidence for anti-TNFα agents, anti-integrin (e.g., vedolizumab), or anti-IL-12/IL-23 agents (e.g., ustekinumab) and Janus kinase inhibitors is currently too low or nonexistent to use them solely for chemoprevention in UC or CD patients. Key Message: Intestinal inflammation is one of the main risk factors for developing CRC in IBD, and all drugs that induce and maintain mucosal healing most likely also decrease the IBD-associated CRC risk. Thus, a therapeutic strategy of adding a 5-ASA therapy to a successfully mucosal healing-inducing therapy, for example, with a biologic or a small molecule merely to prevent CRC appears to be obsolete.