Is there friction within the Interphone study group?
April 18... Is
there friction within the Interphone study group? An exchange of letters in today's
issue of the Journal of the National Cancer Institute (JNCI) exposes a
rift between the Swedish Interphone group led by Maria Feychting and the Danish
and German Interphone groups led by Joachim Schüz and Christoffer Johansen,
respectively. At issue is the nature and extent of a possible tumor risk among
long-term mobile phone users.
Late last year, Schüz and Johansen updated their analysis of a Danish cohort
and concluded that it provides "evidence that any large association of risk
of cancer and cellular telephone use can be excluded." (Schüz is now at
the Danish Cancer Society in Copenhagen, where Johansen also works.)
In a letter to the JNCI, Feychting and
Anders Ahlbom, both of the Karolinska Institute in Stockholm, counter that
"such a global conclusion is premature and not supported by the
data." They go on: "Although results from this and other studies
concerning short-term use are reassuring, we do not see how these data provide
convincing evidence against an effect of long-term use which for some time has
been the critical issue in evaluations of potential health risks related to
mobile phone use."
In their reply, Schüz and the other members of the
Danish study team including John Boice and Joseph McLaughlin of the International Epidemiology Institute in Bethesda, MD appear to back off from their
original conclusion, acknowledging that "further study is warranted to
evaluate the possibility of an association between long-term cellular telephone
use and brain tumor risk."
Interestingly, Elisabeth Cardis of IARC in
Lyon, France, who is the principal investigator of the overall Interphone
project, signed the letter from the Swedish team, as did Paul Elliott of Imperial College, London.
One additional comment: The Schüz letter could easily mislead the uninitiated
reader into thinking that the Interphone results published so far do not show a
link between long-term use and acoustic neuroma, a tumor of the acoustic nerve.
In fact, they do. The Danish study did not find an association, but that may be
because a cohort study offers no information about on which side of the head
the phone was used (laterality) and therefore which side of the head was
exposed to radiation. In their April 18 response, Schüz and coworkers write
that "our acoustic neuroma results are overall consistent with the results
of the pooled five-country study." That five-country study is an analysis from five Interphone
teams Ahlbom, Cardis and Feychting are all among the authors which does have
data on laterality. While it does not show a general elevated risk of acoustic
neuroma after ten or more years of cell phone use, the five-country analysis does
when laterality is added to the mix. Then, a clear statistically significant
tumor risk becomes apparent. This was a key finding of the five-country
analysis and is included in the abstract of the published paper.
Source: http://www.microwavenews.com/
Also under http://jnci.oxfordjournals.org/current.dtl