Excerpt
Patients with ulcerative colitis (UC) have an increased risk of developing colorectal cancer (CRC). A meta-analysis by Eaden et al. [
1] that included 116 studies determined an overall prevalence of CRC in any UC patients of 3.7% and cumulative probabilities of CRC of 2% by 10 years, 8% by 20 years, and 18% by 30 years of UC duration. It also observed a geographic variability in CRC incidence rates from 5/1,000 person-years duration in the US, 4/1,000 person-years duration in UK and 2/1,000 person-years duration in Scandinavia and other countries [
1]. Several other factors have also been suggested to influence the risk of CRC in patients with UC. A population-based cohort study by Anders Ekbom and his group from Sweden observed an increased risk of CRC in association with more anatomically extensive UC [
2]. Patients with pancolitis (SIR 14.8, 95% CI 11.4–18.9) and left-sided colitis (SIR 2.8, 95% CI 1.6–4.4) had a 15-fold and threefold increase in standardized incidence ratio, respectively, whereas those with UC limited to the rectum had lower risk of CRC (SIR 1.7, 95% CI 0.8–3.2) [
2]. Another report from a combined Swedish and English population cohort observed a significantly increased 19.2 excess risk of CRC in those with pancolitis (
p = 0.001) and 3.6 (
p = 0.01) in those with left-sided colitis [
3]. Younger age at the onset of UC was also found to significantly impact the risk of CRC based on data from population-based cohort [
2]. Patients younger than 15 years at the time of UC diagnosis had the highest risk of CRC (SIR 118.3, 95% CI 63.0–202.3) [
2]. An absolute risk of CRC was 40% in patients younger than 15 years of age at the time of initial UC diagnosis, 25% for those aged 15–39 years, and 15% for those aged more than 40 years [
2]. Multivariable logistic regression identified that among analyzed variables, age at the time of UC diagnosis, extent of UC at diagnosis, and duration of follow-up only age younger than 15 years (adjusted SIR 4.03, 95% CI 2.07–7.85) and presence of pancolitis (adjusted SIR 5.27, 95% CI 3.22–8.61) at the time of initial UC diagnosis were significantly associated with four–fivefold increased risk of CRC [
2]. The risk of CRC adjusted for extent of disease at the time of initial diagnosis decreased with each increase in age group at diagnosis (age <15, 15–29, 30–39, 40–49, 50–59, and 60 years and above) [
2]. An analysis of the cohort from an academic referral center determined that severity of histologic inflammation within the colon of UC patients increases the risk of CRC threefold (HR 3.0, 95% CI 1.4–6.3) [
4]. Data from tertiary referral center case–control study found that increasing severity of both endoscopically visible and histological colonic inflammation are associated with 2.5-fold (OR 2.5, 95% CI 1.45–4.44) and fivefold (5.13, 95% CI 2.36–11.14) increased risk of CRC among UC patients when compared to non-CRC UC controls, respectively [
5]. …
