“Microwave News” and an updated meta-analysis on mobile phones and acoustic neuroma

Posted on October 8, 2013

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cellphoneI recently published a letter in the International Journal of Epidemiology entitled “The case of acoustic neuroma: Comment on: Mobile phone use and risk of brain neoplasms and other cancers” in reply to a paper by Benson at al. who used the Million Women study to look at cancer risk from mobile phone use. The letter addressed the fact the authors instead of just reporting their findings (both negative and positive) in the abstract (which, lets face it is what most people read), they only reported the non-significant effects. The only statistically significant increased risk they found was for acoustic neuroma, which does fit in nicely with the conclusion of the IARC monograph working group. However, they only reported this after the effect disappeared after pooling the data with the Danish prospective cohort. As I discussed in my letter, a more transparent, and generally more accepted method would have been to conduct a meta-analysis of all available studies. This meta-analysis (although with a typo) and my letter can be found here (link).

Anyway, this got covered at Microwave News (link):

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[Edit: unfortunately, I cannot post the full article here, so i will stick to some quotes]

“…In a short letter to the International Journal of Epidemiology (IJE), the Oxford team advises that when the analysis was repeated with data from 2009-2011, “there is no longer a significant association.” Also gone, the team writes, is the “significant trend in risk with duration of use.”

“After ten or more years of phone use, the risk of AN is now only 17% higher with a confidence interval (0.60-2.27) that indicates the small increase is not significant. In their earlier paper, the Oxford group reported that the AN tumor risk more than doubled after ten years and was statistically significant (RR = 2.46, CI = 1.07–5.64).”

“The update comes in response to a letter from Frank de Vocht of the U.K.’s University of Manchester expressing surprise that the Oxford team had not included the finding of the AN risk in its original published abstract —especially given that it “provides further support” for the IARC decision to classify RF radiation as a possible human carcinogen.”

 

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However, the last sentence asking for an updated meta-analysis of the Microwave News reporting team is easily solvable. So hereby:

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Effect (lower 95% upper)
Hardell, 2009                  2.90               1.6    5.5
Schuz, 2011                     0.87               0.52 1.46
INTERPHONE, 2011      0.76               0.52 1.11
Benson, 2013                  1.17               0.60 2.27 (note that i assumed from the author’s reply that this is the updated result of their study, and NOT the pooled update!)
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Summary exp(effect): 1.18 95% CI ( 0.67,2.08 )
Estimated heterogeneity variance: 0.25 p= 0.004

Rplot_update

So in conclusion, the results of the updated meta-analysis indicate an 18% increased risk, which does not reach statistical significance. The updated results of the Million Women study seem pretty much on the mark, with only the work by Hardell suggesting a “real increase of risk”.
Had the authors conducted the meta-analysis rather than the “hidden” pooled approach, preferably with the 2011 updated data, it seems to me that much speculation could have been avoided. As for all science, but especially given the “nature of the field” involving heated discussion, transparency should have been the key word!
Nonetheless, discussions will likely be ongoing given the limitations of all epidemiological studies in this meta-analysis, so the conclusion of my letter remains as valid as it was prior to the update:
Future prospective studies with improved exposure assessment using records of mobile phone use, most notably the COSMOS study, will hopefully sway the cumulative results of the meta-analysis in a conclusive direction and settle this debate.
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