Lead author Judith Schwartzbaum, an associate professor of epidemiology at Ohio State University in Columbus, said men and women whose blood samples contained allergy-related antibodies had an almost 50 percent lower risk of developing glioma 20 years later compared with people without signs of allergies.
The study, published online in the Journal of the National Cancer Institute, also suggested the reduced risk is stronger among women than men, although men with certain allergy profiles also have a lower tumor risk.
Glioma have the potential to suppress the immune system to allow the tumors to grow, Schwartzbaum said.
The scientists analyzed blood samples taken from patients decades before they were diagnosed with glioma, Schwartzbaum said.
"The longer before glioma diagnosis that the effect of allergies is present, the less likely it is that the tumor is suppressing allergies. Seeing this association so long before tumor diagnosis suggests that antibodies or some aspect of allergy is reducing tumor risk," Schwartzbaum said in a statement. "It could be that in allergic people, higher levels of circulating antibodies may stimulate the immune system, and that could lower the risk of glioma."
Absence of allergy is the strongest risk factor identified so far for this brain tumor, but there is still more to understand about how this association works, Schwartzbaum said.