title: Risk of colorectal cancer in Asian patients with ulcerative colitis: a systematic review and meta-analysis.
abstract: The increased risk of colorectal cancer in ulcerative colitis is well known. The risk of sporadic colorectal cancer in Asian populations is considered low and risk estimates of colorectal cancer related to ulcerative colitis from Asia vary. This meta-analysis is an Asian perspective on the risk of colorectal cancer related to ulcerative colitis.
  
  
  
  We searched PubMed and Embase for terms related to colorectal cancer in ulcerative colitis from inception to July 1, 2016. The search for published articles was done by country for all countries in Asia. We included studies with information on the prevalence and cumulative risk of colorectal cancer at various timepoints. A random-effects meta-analysis was done to calculate the pooled prevalence as well as a cumulative risk at 10 years, 20 years, and 30 years of disease.
  
  
  
  Our search identified 2575 articles; of which 44 were eligible for inclusion. Our analysis included a total of 31 287 patients with ulcerative colitis with a total of 293 reported colorectal cancers. Using pooled prevalence estimates from various studies, the overall prevalence was 0·85% (95% CI 0·65-1·04). The risks for colorectal cancer were 0·02% (95% CI 0·00-0·04) at 10 years, 4·81% (3·26-6·36) at 20 years, and 13·91% (7·09-20·72) at 30 years. Subgroup analysis by stratifying the studies according to region or period of the study did not reveal any significant differences.
  
  
  
  We found the risk of colorectal cancer in Asian patients with ulcerative colitis was similar to recent estimates in Europe and North America. Adherence to screening is therefore necessary. Larger population-based, prospective studies are required for better estimates of the risk.
  
  
  
  Indo-US Science and Technology Forum.
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sawan
authors.initials: S
authors.lastname: Bopanna
authors.affiliation: Massachusetts General Hospital, Crohn's and Colitis Center, Boston, MA, USA.
authors.forename: Ashwin N
authors.initials: AN
authors.lastname: Ananthakrishnan
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kedia
authors.affiliation: Massachusetts General Hospital, Crohn's and Colitis Center, Boston, MA, USA.
authors.forename: Vijay
authors.initials: V
authors.lastname: Yajnik
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India. Electronic address: vineet.aiims@gmail.com.
authors.forename: Vineet
authors.initials: V
authors.lastname: Ahuja
mesh_terms: D001208:Asia / Q000453:epidemiology; D044466:Asian People; D003093:Colitis, Ulcerative / Q000150:complications* / Q000453:epidemiology / Q000208:ethnology*; D015179:Colorectal Neoplasms / Q000150:complications* / Q000453:epidemiology / Q000208:ethnology*; D006801:Humans; D015995:Prevalence; D012307:Risk Factors