Doubts cast on dental x-ray brain tumour scare
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Serious doubts have been cast, on both sides of the Atlantic on a US study which claimed that there was a link between patient-reported incidence of having bitewings taken and an increased risk of developing meningioma, a brain tumour. The findings were reported in the journal Cancer, but there accuracy and relevance has been questioned by experts in both the USA and the UK. They do not justify the scare-story headlines put out by the media in both countries. |
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NHS Choices has responded by saying that the X-ray 'brain tumour risk' is not proven. It points out that what didn’t make the headlines was that the same study showed that having a series of full-mouth X-rays was not associated with any increased risk of brain tumour. This throws doubt on the suggested link between dental X-rays and brain tumour. Furthermore, participants reported their own history of X-rays rather than researchers checking their dental records. This means people with brain tumours may have been focusing on the potential causes of their cancer and therefore may have been more likely to recall dental X-rays than people without one, potentially biasing the results.
Most importantly though, NHS Choices says, the chance of developing a brain tumour is very small and, even if X-rays can double the risk, it would still be a very rare event. According to one academic quoted in the press, this doubling of risk actually translated into just a 0.07% increase in lifetime risk, once the overall rarity of brain tumours was taken into account
NHS Choices concludes that while this study suggests that dental X-rays may be linked to brain tumour, it falls short of proving an actual link. It is known that exposure to ionising radiation is linked to cancer (which is why X-ray use is kept to a minimum), but people should not be alarmed by today’s sensationalist headlines and should not be dissuaded from having dental X-rays when recommended by their dentist.
Meanwhile in the USA a dentist blogger, The Dental Warrior, has written to the American Cancer Society, in whose journal the article was published, saying he will not contribute another cent to them, despite being a regular contributor for many years.. ‘Shame on you for publishing a “study” so grossly flawed’ he writes.
He continues: ‘The so-called research for this so-called “study” was so flawed as to be truly laughable (if it wasn’t being so recklessly used to misinform the public). To correlate ANECDOTAL recollections (asking subjects to remember) of what x-rays they’ve had since they were children is the ANTITHESIS of science. Any LEGITIMATE scientific organization would be in hysterics when presented such a ridiculous notion of a “study.” I’m truly stunned that this got published as “science.” As a dentist, even I don’t recall what my own x-ray history is.
He has published a letter he has received from the American Cancer Society. He is not impressed and concludes: ‘I could just as easily fashion a study to demonstrate meningiomas being caused by fluorescent lighting… by asking all those patients, “Did you spend a lot of time under fluorescent lights as a child?” You did? Oh, well then… THAT’S what must have caused the tumors. Brilliant! Not. Correlation (especially one based on anecdote) does not equal causation.’
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