Allergies may protect against brain cancer
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A history of allergies may reduce the risk of a particular type of brain tumor called glioma, investigators report in the Journal of the National Cancer Institute.
Little is known about what causes glioma, note Dr. Eleni Linos, of Harvard School of Public Health, Boston, Massachusetts, and colleagues. “Atopic (allergic) diseases are on the rise in western populations, with increasing interest in their long-term health consequences,” they point out. “An inverse association between (allergy) and the risk of glioma has been observed.”
To investigate further, the researchers conducted a systematic review and pooled analysis of published studies that quantified the association between asthma, eczema, or allergy and a medically confirmed diagnosis of glioma or another type of brain tumor called meningioma.
A total of eight studies with 3,450 patients diagnosed with glioma and 1,070 patients with meningioma were included in the analysis.
They found that the relative risk of glioma was markedly lower in those with a history of allergy, asthma or eczema, compared to those with no history of allergic disease.
There was no overall significant association between allergy and meningioma. However, the information on this disease was limited.
There are several possible reasons why allergies might offer protection against brain cancer. Immune factors that are involved in or predispose people to allergies might play a role. It is also possible that medications used to treat these conditions could offer some protection. Other factors including some that are not involved with the immune system may also affect the risk.
SOURCE: Journal of the National Cancer Institute, October 17, 2007.
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