Important changes in the pattern of colorectal cancer in patients with inflammatory bowel disease

Abstract

1Department of Epidemiology Research, National Health Surveillance & Research, Orestads Boulevard 5, DK-2300 Copenhagen S, Denmark *Author for correspondence: Tel.: +45 32 68 37 22; tjs@ssi.dk It is generally accepted that both ulcerative colitis (UC) and colonic Crohn’s disease (CD) are associated with an increased risk of colorectal cancer (CRC) [1], but the magnitude of the risk is subject to debate and may have changed over time. Previous reports of severely ill patients referred to tertiary centers suggested a markedly increased risk of CRC in UC, as reflected in a metaanalysis by Eaden and colleagues published in 2001 [2]. The meta-analysis was based on both referral center populations, surgical series, surveillance programs, populationbased cohorts and histology series and reported a cumulative risk of CRC in UC of 2, 8 and 18% after 10, 20 and 30 years, respectively. However, acknowledging that only prognostic data from an unselected patient population (representing the whole spectrum of disease) apply to the average inflammatory bowel disease (IBD) patient, a new meta-analysis was conducted in 2012 [3]. It revealed a 2.4-fold increased risk of CRC in patients with UC, estimated from eight population-based studies covering the time period from 1954 to 2004. However, despite the 2.4-fold increased relative risk, the absolute risk of CRC was only 1.6% overall after 7–24 years (mean: 14 years) of follow-up, with a cumulative probability of CRC of less than 1% at 10 years, 0.4–2% at 15 years and 1.1–5.3% at 20 years follow-up. Notably, these numbers also included sporadic cases of CRC. In addition to a limited absolute risk of CRC in UC, one has to consider the marked changes in the management of IBD over the past 30–40 years. These changes include altered use and type of diagnostics and surgery; increased use of medical therapy, with a shift from the era of sulfasalazine, 5-aminosalicylic acid and corticosteroid treatment to the era of immunomodulatory agents, such as thiopurines; and TNF antagonists. Studies on 5-aminosalicylic acid use and risk of CRC have failed to show a chemopreventive effect [4], whereas thiopurines have recently been suggested to reduce the risk of CRC among patients with IBD [5]. Most likely, “...the absolute risk of colorectal cancer in inflammatory bowel disease is limited and a marked decrease in both risk of colorectal cancer and mortality from colorectal cancer has been observed among patients with ulcerative colitis...” EDITORIAL