A new study published in the official journal of the American Cancer Society — which is aptly titled Cancer — found that dental X-rays can significantly increase the likelihood of developing non-malignant brain tumors over the course of a lifetime.
1,433 patients with meningiomas — the most common type of brain tumor — were asked about their dental history; their responses were compared with those of a control group consisting of 1,350 tumor-free individuals.
Those with meningiomas were up to twice more likely to report having undergone bitewing X-rays on an annual basis.
Dr. Elizabeth Brooks Claus of Yale's School of Public Health, who led the study, said exposure to ionizing radiation during the X-rays was a major contributor to the increased risk of tumor development.
The American Dental Association recommends adults be X-rayed every two to three years; children, every one to two years. But Claus noted that "people get more dental X-rays more frequently than the American Dental Association says."
The American Cancer Society's Chief Medical Officer, Dr. Otis Brawley, pointed out that relying on patients' memories for data can be tricky. The ADA also took issue with Claus's use of information recall. "Studies have shown that the ability to recall information is often imperfect," said the ADA in a statement. "Therefore, the results of studies that use this design can be unreliable."
But Brawley did acknowledge that some 1% of cancers reported in the US are caused by medical radiation. "It's a cautionary tale," said Dr. Donald O'Rourke of the University of Pennsylvania. "We do know that radiation can cause tumors, and we have to be judicious with its use."