Asthma patients are at a lower risk for developing brain cancer, study finds

• Having asthma or allergies lowers the risk of developing brain cancer, according to a team of international researchers.
• They found that patients with asthma or allergic conditions were up to two thirds less likely than patients without these conditions to develop glioblastoma multiforme (GBM), the most common primary malignant brain tumour.
• The study included 111 patients with GBM and 422 patients without GBM, who acted as a control group.
• Their average age was about 55 years.
• The researchers carried out interviews to determine the number of people with asthma or allergies that had been diagnosed by a physician, and took blood samples to carry out a genetic analysis.
• About 5 per cent of patients with GBM reported that they had asthma, compared with 9 per cent of the control group.
• The researchers tound that having asthma reduced the risk of GBM by 53 per cent, while having eczema reduced the risk of GBM by 60 per cent.
• The genetic analysis looked at slight variations in two genes that had previously been associated with asthma.
• One of these genes coded for the cytokine interleukin-13, while the other coded for the receptor of the cytokine interleukin-4.
• The researchers found that a combination of these genetic variants, which increased the risk of asthma by 1.8 times, reduced the risk of GBM by two thirds.
• Lead researcher Dr Judith Schwartzbaum, associate professor of public health at Ohio State University in the US, said that the mechanism by which the cytokines affected the risk of GBM was unknown.
• 'I'm not sure if these cytokines play independent roles in both allergies and the development of brain tumours, if allergies and GBM share a common pathway in the immune system, or if it is allergies themselves that reduce GBM risk,' she said.