title: Colorectal cancer incidence in the Aboriginal population of Ontario, 1998 to 2009.
abstract: BACKGROUND
  Studies suggest that colorectal cancer incidence increased disproportionately among the Aboriginal population of Ontario relative to the general population. Using an ecological approach, this study examined colorectal cancer incidence for the 1998-to-2009 period among Aboriginal people living in Ontario.
  
  
  METHODS
  Based on their postal code when they were diagnosed, cases of colorectal cancer identified from the Ontario Cancer Registry were assigned to census geographic areas with high (33% or more) or low percentages of Aboriginal identity residents, using the Postal Code Conversion File Plus (PCCF+). To account for potential misclassification by the PCCF+, Indian reserves for which assignment through postal codes is likely to be accurate were identified. Age-standardized incidence rates and rate ratios were calculated to compare colorectal cancer incidence in high-Aboriginal identity areas or on Indian reserves with incidence in low-Aboriginal identity areas.
  
  
  RESULTS
  Colorectal cancer incidence was significantly higher for residents of high- versus low-Aboriginal identity areas in Ontario (rate ratio for men = 1.44, 95% CI = 1.26-1.63; rate ratio for women = 1.42, 95% CI = 1.23-1.63), a disparity that persisted by age group. When the Aboriginal sample was limited to residents of Indian reserves, the difference was statistically significant only for men and for people aged 50 to 74.
  
  
  CONCLUSIONS
  The incidence of colorectal cancer differs across areas of Ontario with high and low percentages of Aboriginal identity residents.
authors: Prevention and Cancer Control, Cancer Care Ontario, Toronto, Ontario.
authors: Stephanie W
authors: SW
authors: Young
authors: Prevention and Cancer Control, Cancer Care Ontario, Toronto, Ontario.
authors: E Diane
authors: ED
authors: Nishri
authors: Prevention and Cancer Control, Cancer Care Ontario, Toronto, Ontario.
authors: Elisa
authors: E
authors: Candido
authors: Prevention and Cancer Control, Cancer Care Ontario, and the University of Toronto, Toronto, Ontario.
authors: Loraine D
authors: LD
authors: Marrett
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000208:ethnology*; D005260:Female; D006801:Humans; D015994:Incidence; D007198:Indians, North American / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D017678:Sex Distribution; D012959:Socioeconomic Factors
keywords: Data linkage; First Nations health; ecological studies