Allergies may be linked to lower risk of brain tumours known as gliomas, especially among women, suggests a new US research.
It also bolsters scientists' belief that something about having allergies or a related factor lowers the risk for this cancer, which can potentially suppress the immune system and allow tumours to grow. A brain glioma causes headaches, nausea and vomiting.
Scientists analysed stored blood samples taken from patients decades before they were diagnosed with glioma. Men and women whose blood samples contained allergy-related antibodies had an almost 50 percent lower risk of developing glioma 20 years later compared to people without signs of allergies, the Journal of the National Cancer Institute reports.
"This is our most important finding. 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," said Judith Schwartzbaum, associate professor of epidemiology at Ohio State University, who led the study.
"Absence of allergy is the strongest risk factor identified so far for this brain tumour, and there is still more to understand about how this association works," added Schwartzbaum, according to an Ohio statement.
The current study also suggested that women whose blood samples tested positive for specific allergy antibodies had at least a 50 percent lower risk for the most serious and common type of these tumours, called glioblastoma.
This effect for specific antibodies was not seen in men. However, men who tested positive for both specific antibodies and antibodies of unknown function had a 20 percent lower risk of this tumor than did men who tested negative.
Glioblastomas constitute up to 60 percent of adult tumours starting in the brain in the US, affecting an estimated three in 100,000 people. Patients who undergo surgery, radiation and chemotherapy survive, on average, for about one year, with fewer than a quarter of patients surviving up to two years and fewer than 10 percent surviving up to five years.