ABO blood group and the risk of pancreatic cancer.
BACKGROUND
Other than several rare, highly penetrant familial syndromes, genetic risk factors for sporadic pancreatic cancer are largely unknown. ABO blood type is an inherited characteristic that in previous small studies has been associated with the risk of gastrointestinal malignancies.


METHODS
We separately examined the relationship between ABO blood type and the risk of incident pancreatic cancer in two large, independent, prospective cohort studies (the Nurses' Health Study and Health Professionals Follow-up Study) that collected blood group data on 107 503 US health professionals. Hazard ratios for pancreatic cancer by ABO blood type were calculated using Cox proportional hazards models with adjustment for other known risk factors, including age, tobacco use, body mass index, physical activity, and history of diabetes mellitus. All statistical tests were two-sided.


RESULTS
During 927 995 person-years of follow-up, 316 participants developed pancreatic cancer. ABO blood type was associated with the risk of developing pancreatic cancer (P = .004; log-rank test). Compared with participants with blood group O, those with blood groups A, AB, or B were more likely to develop pancreatic cancer (adjusted hazard ratios for incident pancreatic cancer were 1.32 [95% confidence interval {CI} = 1.02 to 1.72], 1.51 [95% CI = 1.02 to 2.23], and 1.72 [95% CI = 1.25 to 2.38], respectively). The association between blood type and pancreatic cancer risk was nearly identical in the two cohorts (P(interaction) = .97). Overall, 17% of the pancreatic cancer cases were attributable to inheriting a non-O blood group (blood group A, B, or AB). The age-adjusted incidence rates for pancreatic cancer per 100 000 person-years were 27 (95% CI = 23 to 33) for participants with blood type O, 36 (95% CI = 26 to 50) for those with blood type A, 41 (95% CI = 31 to 56) for those with blood type AB, and 46 (95% CI = 32 to 68) for those with blood type B.


CONCLUSIONS
In two large, independent populations, ABO blood type was statistically significantly associated with the risk of pancreatic cancer. Further studies are necessary to define the mechanisms by which ABO blood type or closely linked genetic variants may influence pancreatic cancer risk.
Wolpin
Brian M
BM
Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA. bwolpin@partners.org
Chan
Andrew T
AT
Hartge
Patricia
P
Chanock
Stephen J
SJ
Kraft
Peter
P
Hunter
David J
DJ
Giovannucci
Edward L
EL
Fuchs
Charles S
CS
D000017:ABO Blood-Group System / Q000235:genetics; D000328:Adult; D000367:Age Factors; D000368:Aged; D016001:Confidence Intervals; D004198:Disease Susceptibility; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010190:Pancreatic Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000235:genetics / Q000276:immunology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012107:Research Design; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
D000017:ABO Blood-Group System