A recent study by the National Cancer Institute shows that a patient’s blood type may increase his or her risk of developing pancreatic cancer.

Pancreatic cancer is a rare form of the disease, accounting for an average of only 29,000 diagnoses in the United States every year. There are more than 42,000 estimated cases this year alone. Pancreatic cancer is difficult to detect, especially in early stages, and spreads quickly. Symptoms include jaundice, abdominal pain, bowel obstruction, and weight loss (because the pancreas is unable to properly metabolize sugar).

Blood type is determined by the ABO gene, found on a region of the 9^th chromosome (typically referred to as “region 9”). Glycoproteins are produced in different combinations to determine an individual’s blood type—either A, B, AB, or O. Blood type dictates how sugars are placed on the cell’s surface. In pancreatic tumor cells, this transference is different.

Although it is relatively rare, pancreatic cancer is extremely life threatening because many people are not diagnosed until after it has already spread. Risk is greater for male smokers over the age of 60 with a family history of the disease.  According to Pancreatic Cancer Action Network (PanCAN), it is the fourth leading cause of cancer death in the United States, and fewer than 5% of patients survive five years following diagnosis.

The relationship between blood type and pancreatic cancer was first suggested more than half a century ago when research in the 50s and 60s yielded similar results. The results of the study come from Nurses' Health Study and Health Professionals Follow-up Study, associated a 17% greater risk for pancreatic cancer for patients with non-O blood types.

The Pancreatic Cancer Cohort Consortium, an organization of 12 academic medical centers, conducted the study with the help of the National Cancer Institute. Researchers followed 4,353 individuals with pancreatic cancer and 4,593 without, using whole-genome scans to detect similar genetic patterns that may be related to the disease.

“As more variants are discovered and follow-up studies are conducted to examine the biological effects of these variants,” says co-author Stephen J. Chanock, M.D., chief of NCI’s Laboratory of Translational Genomics in DCEG, “a better understanding will emerge of the inherited risk factors and mechanisms that lead to the development of pancreatic cancer."

Both tests showed a greater risk for patients with A and B blood types. The first of the two experiments in March, 2009, showed that blood type A had a 32% higher risk, with type AB increasing by 51% and type B increasing by 72% for risk of pancreatic cancer development.

Co-author Patricia Hartge, Sc.D., also of NCI's Division of Cancer Epidemiology and Genetics, says much more work is needed to better understand the link between blood type and pancreatic cancer: “This finding may lead to improved diagnostic and therapeutic interventions that are so desperately needed."

The study will be published in this month’s online issue of Nature Genetics. Click here to read the study’s extract, or find more information about pancreatic cancer.

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