There have been a number of stories in the press regarding the recent paper by Claus et al on dental X-rays and meningiomas. Meningiomas are mostly benign tumours which arise from the dura mater and are usually slow-growing. They are the most common benign brain tumour although relatively uncommon with an incidence of around 6 per 100,000 and a female:male ratio is 2:1 . The aim of the Claus study was to examine the association between dental x-rays and the risk of intracranial meningioma.
What did they do?
The authors identified all individuals aged 20-70) with histologically confirmed intracranial meningioma in several states ( cases)over a 5 year period using Rapid Case Ascertainment (RCA) systems and state cancer registries. Controls were matched to cases by 5-year age interval, sex, and state of residence excluding those with previous history of meningioma and/or a brain lesion of unknown outcome.
Following approvals participants were contacted for a telephone interview, questions included onset, frequency, and type of dental care received including the number of times they had received radiographs (bitewing, full-mouth, or panoramic [panorex]), during 4 time periods: when aged <10 years, 10-19 yrs,20 -49 years, ≥50 years. Information also was gathered on the occurrence and timing of therapeutic radiation treatments.
A conditional logistic regression was used to assess the odds of meningioma associated with risk factors. individuals who had received therapeutic radiation were removed from all analyses that assessed the risk associated with dental x-rays
What did they report?
- Cases were more than twice as likely as controls to report having ever had a bitewings
- individuals who reported receiving bitewings on a yearly basis or more had an elevated risk for ages <
- An increased risk of meningioma also was associated with panorex films taken at a young age or on a yearly basis or more.
- No association was appreciated for tumour location above or below the tentorium.
[table id=25 /]
[table id=26 /]
What did they conclude
Our findings suggest that dental x-rays, particularly when obtained frequently and at a young age, may be associated with an increased risk of intracranial meningioma, at least for the dosing received by our study participants.
Claus, E. B., Calvocoressi, L., Bondy, M. L., Schildkraut, J. M., Wiemels, J. L. and Wrensch, M. (2012), Dental x-rays and risk of meningioma. Cancer. doi: 10.1002/cncr.26625
Things to consider
- This was a large study but there is no formal power calculation.
- The average length of the telephone interview was 52 minutes – How effective are telephone interviews at eliciting this type of information , is recall and honesty a greater or lesser problem than with a face to face interview?
- There is some discussion regarding the potential recall bias relating to the number and type of dental radiographs. This is discussed in the paper and it is suggested that recall for dental radiographs high but the studies quoted were much smaller.
- The controls were more likely to have ≥16 years of education and to have an annual salary >$75,000.
- It is interesting that ORs are higher for ‘bitewings at any age’ when you would anticipate that for older patients with longer dental histories there may potentially be a dose related effect so you might expect the ORs to be greater in the >50s.
- While the panorex data does suggest a higher risk these are all based on small numbers of patients.
- As noted in the Daily telegraph article, this is a rare disease so if this evidence was confirmed it would mean that the lifetime risk of meningioma would increase from 15 in every 10,000 people to 22 in 10,000
- Finally while this study does not raise significant concerns it is a timely reminder that dental x-rays should only be prescribed where there is a clear clinical need so as to reduce unnecessary exposure to ionising radiation.
Selection criteria for Dental radiographs from the Faculty of General Dental Practitioners
Further information on Meningiomas
Wiemels J, Wrensch M, Claus EB. Epidemiology and etiology of meningioma. J Neurooncol. 2010 Sep;99(3):307-14. Epub 2010 Sep 7. Review. PubMed PMID: 20821343; PubMed Central PMCID: PMC2945461.