title: Screening prevalence and incidence of colorectal cancer among American Indian/Alaskan natives in the Indian Health Service.
abstract: BACKGROUND
  Studies on colorectal cancer (CRC) screening and incidence among American Indian/Alaska Natives (AI/AN) are few.
  
  
  OBJECTIVE
  Our aim was to determine CRC screening prevalence and to calculate CRC incidence among AI/AN receiving care within the Indian Health Service (IHS).
  
  
  METHODS
  A retrospective cohort study of AI/AN who utilized IHS from 1996 to 2004. AI/AN who were average-risk for CRC and received primary care within IHS were identified by searching the IHS Resource Patient Management System for selected ICD-9/CPT codes (n = 142,051). CRC screening prevalence was calculated and predictors of screening were determined for this group. CRC incidence rates were ascertained for the entire AI/AN population ages 50-80 who received IHS medical care between 1996 and 2004 (n = 283,717).
  
  
  RESULTS
  CRC screening was performed in 4.0% of average-risk AI/AN. CRC screening was more common among women than men (RR = 1.6, 95% CI 1.4-1.7) and among AI/AN living in the Alaska region compared to the Pacific Coast region (RR = 2.5, 95% CI 2.2-2.8) while patients living in the Northern Plains (RR = 0.4, 95% CI 0.3-0.4) were less likely to have been screened. CRC screening was less common among patients with a greater number of primary care visits. The age-adjusted CRC incidence among AI/AN ages 50-80 was 227 cancers per 100,000 person-years.
  
  
  CONCLUSIONS
  CRC was common among AI/AN receiving medical care within IHS. However, CRC screening prevalence was far lower than has been reported for the U.S. population.
authors.affiliation: Division of Gastroenterology, San Francisco General Hospital (3D), 1001 Potrero Avenue, San Francisco, CA 94110, USA. lukejohn.day@ucsf.edu
authors.forename: Lukejohn W
authors.initials: LW
authors.lastname: Day
authors.forename: David K
authors.initials: DK
authors.lastname: Espey
authors.forename: Erin
authors.initials: E
authors.lastname: Madden
authors.forename: Mark
authors.initials: M
authors.lastname: Segal
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Terdiman
mesh_terms: D000368:Aged; D000413:Alaska / Q000453:epidemiology; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007198:Indians, North American / Q000706:statistics & numerical data*; D004930:Inuit / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology