Asthma or Allergies May Reduce Risk of Brain Cancer
Having asthma, hay fever or another allergic condition
may reduce the risk of developing one fatal form of brain cancer,
a new study suggests. The scientists say that new evidence for
this relationship is found in the normal variation of two genes.
“Variations in certain genes may make a person more prone
to develop asthma or allergies and those same variations may
protect adults against the most common kind of brain cancer,” said
Judith Schwartzbaum, the study’s lead author and an associate
professor of public health at Ohio State University.
Glioblastoma Multiforme Statistics
Glioblastoma multiforme (GBM), one of the most common forms of
brain cancer, affects three out of 100,000 people, but if for
people 65 and older that rate that quadruples to 13 out of
100,000. The average five-year survival rate from the time
of diagnosis for GBM is only 3.3 percent, and is lower for
people 65 and older.
The current study
supports several years’ worth of research
by other scientists who have suggested an inverse relationship
between asthma, allergies and GBM. But those studies were based
only on information that participants gave about their history
of asthma and allergies, not on information from DNA testing.
“We needed an objective way to measure the accuracy of
allergy self reports, one that isn’t affected by the presence
of a brain tumor,” Schwartzbaum said. “Looking at
genetic variation is one way to do this.”
The study is the first to include a genetic component in addition
to participant self-reports of asthma and allergy. The findings
appear in the July 2005 issue of the journal Cancer Research.
The kind of genetic variant Schwartzbaum is talking about is
called a polymorphism. While a mutation consists of a rare and
abnormal DNA pattern, a polymorphism consists of common patterns,
each considered normal.
offer protection against certain diseases or render a person
more vulnerable to particular conditions.
For example, researchers suspect that several polymorphic forms
of key genes may increase susceptibility to Alzheimer’s
“People who have polymorphisms in the two genes that we
examined may be susceptible to allergic conditions and may also
have a lower risk of GBM,” Schwartzbaum said.
Schwartzbaum and her colleagues analyzed DNA samples from 533
people, 111 of whom had been diagnosed with GBM. The other 422
randomly selected participants served as controls. All of the
subjects were asked if they had ever been diagnosed with asthma,
hay fever or eczema and, if so, how long each of these conditions
The researchers looked for polymorphisms on two genes associated
with asthma and allergies, IL-4RA and IL-13. In this study, individuals
with one or two specific polymorphisms on the IL-4RA gene that
increase asthma susceptibility seemed to have a lower GBM risk.
The same was true for two polymorphisms on the IL-13 gene.
“Our results suggest that self-reports of asthma and allergy
are a pretty accurate way to determine someone’s susceptibility
to this particular type of cancer,” Schwartzbaum said. “It’s
also important to realize that someone could have these asthma-susceptibility
polymorphisms and never experience asthma or allergies.”
Next Step in Allergy and Asthma GBM Research
Schwartzbaum’s next goal is to figure out the relationship
between these allergy-inducing polymorphisms and GBM.
IL-4RA and IL-13 genes code for chemical messengers called cytokines,
which control how immune system cells communicate and behave.
Ironically, these cytokines may calm the immune system in the
brain by helping to inhibit inflammation, even though they also
eventually lead to increased inflammation in the lungs, which
is a primary symptom of asthma.
Schwartzbaum said, that the anti-inflammatory role of these
cytokines may hinder tumor growth.
“I’m not sure if these cytokines play independent
roles in both allergies and the development of brain tumors,
if allergies and GBM share a common pathway in the immune system,
or if it is allergies themselves that reduce GBM risk,” she
At any rate, having asthma or other allergic conditions may
be somewhat beneficial.
Schwartzbaum conducted the study with researchers from Sweden,
England and Wake Forest University in Wake Forest, North Carolina.
The group received funding from the National Cancer Institute,
the Swedish Council for Working Life and Social Research, the
Swedish Cancer Society, the Swedish Research Council, the European
Union Fifth Framework Program and the International Union Against
Ohio State University
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