By Will Dunham

WASHINGTON (Reuters) - People with type O blood have a much lower risk for pancreatic cancer, while those with type B blood have the worst risk, researchers said on Tuesday in a study that may help explain what causes one of the deadliest kinds of cancer.

Compared to people with type O, those with blood type A have a 32 percent higher risk of pancreatic cancer, those with type AB have a 51 percent higher risk and those with type B have a 72 percent higher risk, the researchers found.

The findings, appearing in the Journal of the National Cancer Institute, were based on 107,503 men and women whose health has been tracked since the 1970s and 1980s.

The findings are not likely to have immediate value for doctors and patients dealing with the disease, but could play a role in the future in developing useful screening methods, said Dr. Brian Wolpin of the Dana-Farber Cancer Institute in Boston and Harvard Medical School, who led the study.

Finding this association between blood type and pancreatic cancer risk gives scientists new insight into the biological mechanisms involved in the disease, Wolpin said.

"There are very few known genetic risk factors for pancreatic cancer. And what this study shows is that blood type, which is defined by a gene on your ninth chromosome, appears to be associated with risk of developing this disease," Wolpin said in a telephone interview.

"It may indicate that either this gene that defines your blood type, or a nearby gene on chromosome nine, is important and may actually be an inherited risk factor for pancreatic cancer," Wolpin added.

The American Cancer Society says 34,290 Americans die of pancreatic cancer every year, making it the fourth leading cause of cancer death in the United States.

Pancreatic cancer often spreads quickly and in many people is not detected until it is in an advanced stage when surgical removal is not possible.

(Editing by Maggie Fox, Editing by Sandra Maler)

Related MedlinePlus Pages:

• Blood and Blood Disorders
• Pancreatic Cancer