Allergies, Asthma May Protect Against Brain Cancer
Study Shows a Genetic Link Between the 2
July 15, 2005 -- Early genetic research raises the possibility that allergies and asthma may help protect against a deadly form of brain cancer.
The findings, while preliminary, could help advance the understanding of the immune system's role in cancer, researchers say.
The newly published study suggests that variations in specific genes that have been linked to asthma, hay fever, and other allergic conditions may also be associated with a decreased risk for the brain tumor known as glioblastoma multiforme.
Glioblastomas, or gliomas, are the most common type of brain cancers and are more common in the elderly. The tumor occurs in 13 out of 100,000 people over age 65, and the five-year survival rate in this age group is very low.
Genetic Link Explored
The study is not the first to suggest that people with allergies appear to have a lower risk of developing the deadly tumor. Researchers with the National Cancer Institute came to the same conclusion in a 2002 study that compared allergy history among people with and without gliomas.
The new study is the first, however, to show a possible genetic reason for the association.
Researchers from Ohio State University and Sweden's Karolinska Institute looked for evidence of common genetic variants on two genes that have been linked to asthma and allergies -- IL4RA and IL-13.
They analyzed DNA samples from 111 patients with glioblastoma tumors and 422 people without brain tumors. The participants were also questioned about their allergy and asthma history.
Epidemiologist and researcher Judith Schwartzbaum, PhD, tells WebMD that people with two specific genetic variants for IL-4RA were twice as likely to have asthma but 40% less likely to have a glioblastoma. A similar association was seen for two variations on the IL-13 gene.
The study is published in the July 15 issue of the journal Cancer Research.
Is Inflammation the Key?
IL-4RA and IL-13 genes help regulate chemical messengers called cytokines, which control the actions of cells that drive the immune system.
Schwartzbaum says it is not yet clear if these chemicals play a direct role in the development of brain tumors or if allergies and gliomas share a common pathway within the immune system.