Having Allergies May Reduce the Risk of Developing Glioma Brain Tumor
Last week, Punxsutawney Phil promised us an early spring this year. The downside of that prediction is that those who suffer from seasonal allergies may begin experiencing symptoms sooner. But researchers have found that there may actually be a benefit to all of the sneezing and sniffling – those who experience allergic reactions may be at a lower risk of developing a hard-to-treat brain tumor called glioma.
Glioma Patients Less Likely to Recall Allergic Reactions
A glioma is the most common form of primary brain tumors. The overgrowth of abnormal glial cells may begin in the brain or spinal cord tissues. Gliomas are classified as either low-grade, which are not benign but have a better prognosis, or high-grade, which are malignant and often cause death within months, despite surgery or treatment with chemotherapy or radiation, according to the National Cancer Institute.
Bridget McCarthy PhD of the University of Illinois at Chicago finds that patients with gliomas were significantly less likely to report having any type of allergy. In fact, patients who had more types of allergies, such as seasonal, medication, pet, or food allergies, had up to a 64% reduction in risk of developing glioma.
McCarthy and colleagues came to their conclusion after evaluating survey data from 419 patients with glioma (344 high-grade and 75 low-grade) and 612 hospital-based control patients who did not have tumors. Even after adjusting for other risk factors, such as age, race and tumor site, those with both high-grade and low-grade tumors were less likely to have an allergy.
The team also evaluated the duration and timing of antihistamine use for treating allergic reactions. At first, oral antihistamine use, especially diphenhydramine hydrochloride (Benadryl) was associated with a lower likelihood of having high-grade tumor, but not low-grade tumor. Further research led the scientists to believe that antihistamine use did not affect the overall results.
More studies are needed to determine the biological mechanisms that link the two conditions. McCarthy suspects that the immune system of people with allergies is hyperactive, and therefore guards against the development of glioma.
"We need to do more studies to really get at that underlying mechanism. Then we might be able to do things that would influence people who might have a higher risk or may have a family history," said McCarthy, a research associate professor of epidemiology.
McCarthy B, et al "Assessment of type of allergy and antihistamine use in the development of glioma" Cancer Epidemiol Biomarkers Prev 2011; 20: 370-378.