People who have had allergies like asthma or hay fever for a long time are up to 25 per cent less likely to get the most common type of Non-Hodgkin Lymphoma (NHL), experts at the University of New South Wales (UNSW) have found.
While making a presentation at the InterLymph Symposium in Sydney, the researchers said that the more atopic diseases the individual had, the less likely they were to succumb to NHL.
They said that people who had three of such conditions were found to be 40 per cent less likely to get NHL.
Having had asthma and hay fever for a long time also appeared to be of greater benefit, they added.
The new findings are significant in view of the rise in the incidence of NHL in developed countries in the past 50 years.
"This was a surprise result. The only known strong risk factors for NHL are immune deficiency and certain infections. This occurs in people with uncontrolled HIV infection, and those who have had a solid organ transplant," said the lead author, Dr Claire Vajdic.
"So we thought other forms of immune dysregulation such as atopic diseases - including hayfever, asthma and food allergies - might relate to the development of lymphoma. It was therefore intuitive to think that these conditions would increase the risk, but in fact, they do the reverse," she said.
The research found that the risk was reduced only in B-cell NHL, the most common type of NHL.
"While the relevant biological mechanisms are not yet known, the pooled data indicate that chronic and multiple atopic conditions impart the greatest reduction in risk. Investigation of the genetic and environmental factors underlying atopy and the apparent inverse effect of atopy on NHL risk will inform our understanding of the complex biological pathways that may be involved," said Dr Vajdic.