sábado, 14 de abril de 2012

Study Examines Possible Link Between Dental X-rays and Meningioma Risk

Article date: April 10, 2012

By Stacy Simon
A new study has found that people diagnosed with meningioma, a tumor of the lining covering the brain, are more likely to report that they’ve received certain types of dental x-rays in the past.
The study does not prove that dental x-rays cause these tumors; much more research would be needed to determine that. And experts say the finding does not change the recommendation to have x-rays only when necessary.
The study was published online April 10, 2012 in the journal Cancer.
Most meningioma tumors are benign (non-cancerous), and they tend to grow slowly. In fact, small tumors that aren’t causing symptoms can often be watched rather than treated. Meningiomas can usually be cured by surgery, though some may come back after treatment.
For the current study, researchers examined answers to a health survey from a group of 1433 meningioma patients and compared them to answers from a control group of 1350 people without these tumors. The meningioma group was twice as likely as the control group to report ever having had a bitewing exam, which uses an x-ray film held in place by a tab between the teeth. The meningioma group also was more likely to report having had a panorex exam at a young age (under 10 years old) or on a yearly or more frequent basis. The panorex exam is taken outside the mouth and shows all of the teeth in one film.
X-rays are a source of ionizing radiation, which is a potential risk factor for meningioma. Some of the participants in the study received their x-rays many years ago, when radiation exposure from dental x-rays was much higher than it is with new technology today.
The study has some drawbacks that make the link between dental x-rays and meningiomas far from certain. Perhaps most importantly, it relied on participants’ memories about their history of dental x-rays (rather than on dental records themselves). Such studies are subject to a phenomenon that scientists call “recall bias,” when people with a disease may be more likely to look for a cause. This might have caused the meningioma patients in the Cancer study to over-report the number of dental x-rays they received, which could have contributed to the findings. Because of this, the study results can only be considered suggestive of a possible link, and more rigorous studies would be needed to prove it.
Otis W. Brawley, M.D., chief medical officer of the American Cancer Society said, "We need more data before we can even begin to state there is a relationship between dental x-rays and these tumors. Until that research is done, the best advice we can give people is to get dental x-rays when they are necessary and only when they are necessary. The dose of radiation given in a bitewing or panoramic x-ray is lower today than it was two decades ago. Nonetheless, x-rays should be done only when necessary. This is true of all x-ray technology, and it's the same advice experts would have given without this study.”
On its Web site, the American Dental Association responded to the study with a statement that said in part, “The ADA’s long-standing position is that dentists should order dental X-rays for patients only when necessary for diagnosis and treatment.” The statement also encouraged patients to talk to their dentists if they have questions about their dental treatment.
Lead author of the study, Elizabeth Claus, MD, PhD, of Yale University School of Medicine, said, “Don’t panic – don’t stop seeing the dentist – but do look at the (ADA) guidelines and discuss them with your dentist to see if you can reduce the number of x-rays you’re getting.”
Reviewed by: Members of the ACS Medical Content Staff

ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases. For reprint requests, please contact permissionrequest@cancer.org.
Citation: Dental X-Rays and Risk of Meningioma. Published online April 10, 2012 in the journal Cancer. First Author: Elizabeth Claus, MD, PhD, Yale University School of Medicine, New Haven, Conn.