December 22, 2010

Thyroid Cancer Is A Concern For Children Exposed To Radiation

(Ivanhoe Newswire) -- Children are exposed to a lot if things that they probably shouldn't be; unfortunately, some instances are worse than others.  It was reported that children exposed to head and neck radiation  -- due to either cancer treatment or multiple diagnosis computed tomography (CT) scan "“ have an increased risk of thyroid cancer for the next 58 years . . . and possibly even longer than that.

Authors state that the data may provide insight into exactly why the rates of thyroid cancer continue to sky rocket, as the general public continues to be exposed to higher doses of radiation through frequently used imaging tests.

"Ionizing radiation is a known carcinogen and, in fact, about 1 million CT scans are performed every year on children five years or younger," which Jacob Adams, M.D., M.P.H., an associate professor in the Department of Community and Preventive Medicine at URMC, was quoted as saying.  "Although CTs and other imaging tests are an important diagnostic tool and radiotherapy is an important treatment modality for cancer, with everything comes a risk.  Our study attempted to measure the very long-term impact on thyroid cancer from medical irradiation.  Our findings strongly suggest that those individuals exposed to irradiation from multiple CT scans to the head, neck and chest during early childhood and individuals treated with radiotherapy to the upper body as children have a lifelong increased risk of thyroid cancer."

Adams along with fellow researchers evaluated potential risks of modern patients by assessing the rates of thyroid cancer in a group that was treated with lower-dose chest radiotherapy in Rochester, N.Y., between 1953 and 1987.  The cohort had been formerly treated for enlarged thymus during infancy, which in fact is a condition that physicians previously thought to be a health problem.  None of the radiation administered was for cancer, and thus the research is not confounded by a susceptibility to the disease.

Adams returned back to his study and re-surveyed the population between 2004 and 2008.    The results were then compared to the health status of the group to their siblings who had not received radiation.  Thyroid cancer occurred in 50 of the 1,303 irradiated patients compared to only 13 of the 1,768 siblings.  The connection between radiation and thyroid cancer remained strong even after researchers accounted for other variables that may possibly contribute to thyroid cancer risk.

Radiation doses in the mid-century group ultimately overlapped with current medical practices; in fact, higher doses and less precision were used years ago.  Doses at the lower end of the study cohort were analogous to a diagnostic pediatric chest CT given in the present day, the study concluded.  Researchers found "“ to little surprise "“ that thyroid cancer risk increased with higher doses of radiation.

SOURCE: Radiation Research, December 22, 2010