title: ABO blood group and risk of colorectal cancer.
abstract: BACKGROUND
  Recent studies have shown an association between non-O blood group and risk of pancreatic cancer. It is unclear whether this association is observed with other gastrointestinal malignancies, including colorectal cancers.
  
  
  METHODS
  We examined the relationship between ABO blood group and the risk of incident colorectal cancer in two large prospective cohorts. We calculated HR using Cox proportional hazard modeling while adjusting for known risk factors of colorectal cancer.
  
  
  RESULTS
  During 996,779 person-years of follow-up, we documented 1,025 incident cases of colorectal cancers. Compared to individuals with blood group O, the multivariate-adjusted HR were 1.08 (95% CI, 0.94-1.24) for blood group A, 1.20 (95% CI, 1.00-1.45) for blood group B, and 1.08 (95% CI, 0.85-1.36) for blood group AB.
  
  
  CONCLUSIONS
  In two large prospective cohorts, we did not observe a statistically significant association between ABO blood group and risk of colorectal cancer.
  
  
  CONCLUSIONS
  These results do not support an association between ABO blood group and risk of colorectal cancer.
authors.affiliation: Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Hamed
authors.initials: H
authors.lastname: Khalili
authors.forename: Brian M
authors.initials: BM
authors.lastname: Wolpin
authors.forename: Edward S
authors.initials: ES
authors.lastname: Huang
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.forename: Peter
authors.initials: P
authors.lastname: Kraft
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000097:blood* / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009726:Nurses / Q000706:statistics & numerical data; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D000017:ABO Blood-Group System