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The more atopic diseases the individual has, the
less likely they are to succumb to NHL. If an individual has three of these
conditions, they are 40 percent less likely to get NHL.
Having had asthma and hay fever for a long time also appears to be of greater
benefit.
The result is significant given that the incidence of NHL in developed countries
has escalated dramatically in the past 50 years. It is three times more
prevalent now than it was in 1950, making it the sixth most common cause of
cancer death in Australia, yet the cause of most cases remains unknown.
“This was a surprise result,” said the lead author, Dr Claire Vajdic. “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.
“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 risk was reduced in B-cell NHL only. This is 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,” said Dr Vajdic. “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.”
The research involved a pooled analysis of data from 13 case-control studies
involving 13,535 NHL cases and 16,388 control participants, funded by the
Leukaemia Foundation.
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