Sunday, June 1, 2014

The art of quoting science - the recent French study on mobile phone use and brain cancer

The publication of the "Mobile phone use and brain tumours in the CERENAT case-control study” by scientists of the French ISPED in Bordeaux initiated a number of international media to report on the issue. Shortly after the publication on 9 May 2014 in the journal Occupational & Environmental Medicine, many news reports appeared claiming a link between brain cancer and mobile phones.

However, the UK Cancer Institute issued comments on why this study is not going to change the weight of evidence(1):

  • people were asked to remember detailed information about their mobile phone use in the past which is prone to recall bias 
  • nearly one fifth of the sampled cancer patients was too sick to fill out the information, so their families were asked to do it for them
  • only in a small sub-group of cases (around 20 glioma cases and 10 meningioma cases) was an association seen, and this is a very small number of cases to base conclusions on as it prone to statistical uncertainty 
  • the study was carried out between 2004-2006, but mobile phone technology has advanced a lot since then

The last point was also underlined by the UK National Health Service who published an article(2) saying: "Arguably the study only provides information about mobile phone use from a decade ago and contributes little in the way of conclusive answers about the current picture".

The resulting media coverage of the publication actually caused the authors to publish a clarification statement on their institute’s website, where they stated: " is important to underline that we are talking about an association and not about a cause-effect relationship. It therefore does not mean that intensive users of mobile phones will develop brain cancer".

However, few people are likely to ever read this clarification by the authors of the study. The general public is left with the message that a link between the use of mobile phones and brain cancer has been found despite the many reviews and contrary conclusions reached by expert panels and health authorities.

The UK Cancer Institute’s blog post concludes: "As it currently stands, it seems unlikely that using a mobile phone can cause brain tumours, particularly as lab research hasn’t shown a biological way this could happen. And rates of the brain tumours in question haven’t seen an increase over time, despite mobile phone use booming. But there isn’t enough good evidence to say with absolute confidence that no risk exists." 

Similarly, the Swedish Radiation Safety Authority, who issued their ninth report on electromagnetic fields just last week(3), said: "…in previous reports the Scientific Council of SSM has concluded that studies of brain tumours and other tumours of the head (vestibular schwannomas, salivary gland), together with national cancer incidence statistics from different countries, are not convincing in linking mobile phone use to the occurrence of glioma or other tumours of the head region among adults. Recent studies do not change this conclusion. Although these have covered longer exposure periods, scientific uncertainty remains for regular mobile phone use for time periods longer than 15 years. It is also too early to draw firm conclusions regarding children and adolescents and risk for brain tumours, but the available literature to date does not indicate an increased risk."

These last two statements, and the many others like them, offer a more considered reflection of the state of knowledge as they are based on a wider review of the science rather than focusing on the results of a single study. Unfortunately, such an approach and the conclusions they reach don’t sell many newspapers.

(1) Back in the news - mobile phones and cancer

(2) Study linking brain cancer and mobiles inconclusive

(3) Swedish Radiation Safety Authority, who issued their ninth report on electromagnetic fields

For more references on findings of international research reviews, have a look at MMF’s viewpoint:

No comments:

Post a Comment