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We thank Calnon et al, Jorgensen, and White et al for reiterating 2 important considerations presented in the “Discussion” section of our article1 that relate to the interpretation of our results: recall bias and the fact that exposures reported by the subjects in our study are from the past when exposure to ionizing radiation associated with dental x-rays was higher than in the current era. Recall bias is an important issue in every case-control study when the validation of reported exposures is not available. Unlike the 2 prior, much smaller studies on the topic (both of which also reported a positive association between meningioma risk and dental x-rays) that performed validation on 147 subjects2 and 163 subjects,3 respectively, in our study, presuming an average of 4 to 5 dentists seen per study participant,2, 3 validation of dental records would require contact with a minimum of 12,000 dentists, a task that is not technically or financially possible. As cohort data sets containing information on both dental x-rays and meningioma are, to our knowledge, ill-defined at the current time, the case-control design (with its associated limitations) remains one important tool with which to gain information regarding associations between this exposure and a diagnosis of intracranial meningioma. Validation of dental x-ray reports has been previously addressed by White et al3 and suggests that although underreporting and overreporting of this exposure does occur, exposure recall is unbiased, with a similar measure of agreement for cases and controls. The authors thus concluded that interview data alone may be used for case-control comparisons of dental x-ray exposure.3

Our response to the concerns raised with regard to the association between therapeutic radiation to the head and the risk of meningioma is that this association is consistently reported and our study, in which a separate analysis was performed for persons reporting such treatment, confirmed these findings.1 The suggestion that pain in the orofacial region associated with meningioma may lead to the increased use of imaging is interesting; in our data, only 1 study subject to date reported such a presenting symptom. The use of propensity scores in case-control studies, although certainly possible, is relatively uncommon and may be associated with artifactual effect modification of the odds ratio.4

It is important for readers to note that the amount of radiation exposure associated with dental x-rays has markedly decreased over the past several decades. As stated by White et al, current exposure levels for any given dental x-ray are likely to be low. Because receipt of medical imaging (including dental x-rays) remains one of the few modifiable exposures to ionizing radiation and the effect of the interaction of cumulative exposure with patient genotype is unclear, it is prudent for patients and health care providers to communicate regarding the use of such technology. We concur with the American Dental Association guidelines and recent reaffirmation that dental x-rays, an important component of good dental care, should be ordered for patients only when necessary for diagnosis and treatment.5

FUNDING SUPPORT

Supported by National Institutes of Health R01 grants CA109468, CA109461, CA109745, CA108473, and CA109475 as well as by the Brain Science Foundation and the Meningioma Mommas.

CONFLICT OF INTEREST DISCLOSURES

The authors made no disclosures.

References

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  • 1
    Claus EB, Calvocoressi L, Bondy ML, Schildkraut JM, Wiemels JL, Wrensch M. Dental x-rays and risk of meningioma [published online ahead of print April 10, 2012]. Cancer. 2012 118 45304537.
  • 2
    Longstreth WT Jr, Phillips LE, Drangsholt M, et al. Dental X-rays and the risk of intracranial meningioma: a population-based case-control study. Cancer. 2004; 100: 1026-1034.
  • 3
    Preston-Martin S, Bernstein L, Maldonado AA, Henderson BE, White SC. A dental x-ray validation study. Comparison of information from patient interviews and dental charts. Am J Epidemiol. 1985; 121: 430-439.
  • 4
    Mansson R, Joffe MM, Sun W, Hennessy S. On the estimation and use of propensity scores in case-control and case-cohort studies. Am J Epidemiol. 2007; 166: 332-339
  • 5
    American Dental Association. http://www.ada.org/. Accessed May 1, 2012.

Elizabeth B. Claus MD, PhD* †, Joseph Wiemels PhD‡, Margaret Wrensch PhD§, * Department of Epidemiology and Public Health Yale University School of Public Health New Haven, Connecticut, † Department of Neurosurgery Brigham and Women's Hospital Boston, assachusetts, ‡ Department of Epidemiology and Biostatistics University of California at San Francisco School of Medicine San Francisco, California, § Department of Epidemiology and Biostatistics Department of Neurological Surgery University of California at San Francisco School of Medicine San Francisco, California.