title: Disparities in prevalence, location, and shape characteristics of colorectal neoplasia between South Korean and U.S. patients.
abstract: BACKGROUND
  Colon cancer screening is being introduced in many countries, but standard Western screening approaches may not be appropriate for Asian societies if differences in colon cancer epidemiology exist. Comparative analysis of colorectal neoplasia patterns in South Korean and Western subjects has implications for appropriate screening approaches in non-Western societies.
  
  
  METHODS
  The results of concurrent screening colonoscopies performed in average-risk patients 50 to 69 years old in 2 teaching hospitals, Kyung Hee University Hospital (Seoul, South Korea) and Virginia Mason Medical Center (Seattle, Wash), were compared with respect to prevalence, histologic features, anatomic distribution, and shape characteristics of colorectal neoplasia.
  
  
  RESULTS
  The U.S. (n = 3460) and South Korean (n = 2193) cohorts were similar with regard to the prevalence of adenomas (28.5% vs 29.8%, respectively, P = .312) and advanced neoplasia (6.4% vs 5.4%, respectively, P = .102), but the proportion of proximal adenomas was greater in the U.S. cohort (62.8% vs 45.9%, P < .001). The prevalence of adenomas and advanced neoplasia was similar in male patients, but there was a greater prevalence of neoplasia (23.5% vs 18.8%, P = .006) and advanced neoplasia (5.1% vs 2.7%, P < .001) in U.S. women than South Korean women. When large (≥10 mm) adenomas were considered, proximal location and nonpolypoid (flat) shape were more common in the U.S. cohort (79.4% vs 37.1%, P = .003 and 43.5% vs 12.3%, P < .001, respectively). The overall prevalence of large flat adenomas in the U.S. cohort was 5 times that of the South Korean cohort (2.6% vs 0.5%, P < .001). Adjustment for sex ratio discrepancies (48.3% men in the U.S. cohort vs 60.8% in the South Korean cohort, P < .001) did not result in any significant changes in the conclusions.
  
  
  CONCLUSIONS
  Compared with Westerners, South Koreans have a more distal distribution of adenomas and advanced neoplasia and lower prevalence of large flat adenomas. South Korean women have a lower prevalence of colorectal neoplasia than Western women. Such disparities suggest that Western screening strategies cannot be directly adopted by other countries, but need to be customized by society.
authors.affiliation: Gastroenterology Division, Kyung Hee University Hospital at Gang Dong, Kyung Hee University School of Medicine, Seoul, South Korea; Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Jae Myung
authors.initials: JM
authors.lastname: Cha
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kozarek
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: La Selva
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Gluck
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ross
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Chiorean
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Koch
authors.affiliation: Digestive Disease Institute, Virginia Mason Medical Center, Seattle, Washington, USA.
authors.forename: Otto S
authors.initials: OS
authors.lastname: Lin
mesh_terms: D000236:Adenoma / Q000453:epidemiology* / Q000473:pathology*; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology