Colorectal cancer in elderly‐onset inflammatory bowel disease: a 1969–2017 Scandinavian register‐based cohort study

BACKGROUND: Previous research indicates that the increased relative risk of colorectal cancer (CRC) in inflammatory bowel disease (IBD) is limited to young‐onset IBD. AIM: To estimate risks of incident CRC and death from CRC in elderly‐onset IBD METHODS: Patients diagnosed with IBD at age ≥ 60 years between 1969 and 2017 were identified using Danish and Swedish National Patient Registers and histopathology data. We linked data to Cancer and Causes of Death Registers and used Cox regression to estimate hazard ratios (HRs) for CRC diagnosis and death compared to matched (by sex, age, and region) IBD‐free individuals. RESULTS: Among 7869 patients with Crohn's disease followed for 54,220 person‐years, and 21,224 patients with ulcerative colitis (UC) followed for 142,635 person‐years, 2.10% and 1.90% were diagnosed with CRC, compared to 2.26% and 2.34% of reference individuals (median follow‐up 6 and 7 years). The incidence of CRC was elevated during the first year after IBD diagnosis: 4.36 (95% CI = 3.33–5.71) in Crohn's disease and 2.48 (95% CI = 2.03–3.02) in UC, but decreased after the first year of follow‐up: 0.69 (95% CI = 0.56–0.86) and 0.78 (95% CI = 0.69–0.88). Once diagnosed with CRC, the risk of CRC death was similar for IBD patients and the general population. CONCLUSION: The excess risk of CRC in elderly‐onset IBD was probably due to bias and not observed beyond the first year. From 2010, the HR for CRC diagnosis more than 1 year after initial IBD diagnosis was lower than in the largely unscreened reference population, supporting the benefit of endoscopic screening and surveillance in patients with IBD.