ABO blood type linked to risk for pancreatic cancer

Patients with type A, B or AB blood may be at an increased risk for developing incident pancreatic cancer, according to data from an analysis of two independent prospective cohort studies. This means that approximately 17% of pancreatic cancer cases were attributable to one of these blood types.

Researchers analyzed blood group data for 107,503 health professionals who participated in the Nurses’ Health Study and the Health Professionals Follow-up Study. They calculated HRs for pancreatic cancer by ABO blood type. Mean follow-up was 8.6 years.

Pancreatic cancer developed among 316 participants between 1996 and 2005. With both cohorts combined, participants with A (HR=1.32), AB (HR=1.51) or B (HR=1.72) blood groups were more likely to develop pancreatic cancer compared with participants with blood group O.

During nine years of follow-up, the absolute age-adjusted rate for pancreatic cancer was 0.24% for blood type O, 0.31% for blood type A, 0.36% for blood type AB and 0.41% for blood type B. Compared with participants with blood group O, those with any blood group antigen A had an adjusted HR of 1.36 (95% CI, 1.06 to 1.74) and those with any blood group antigen B had an adjusted HR of 1.64 (95% CI, 1.24 to 2.17). However, Rh type was not associated with pancreatic cancer risk, according to the researchers.

“The association between blood group and pancreatic cancer risk was not statistically significantly modified by other known risk factors for pancreatic cancer, including age, sex, smoking status, BMI or physical activity,” the researchers wrote.

Wolpin BM. J Natl Cancer Inst. 2009;49:570-577.