CT scans and cancer risk analyzed

Researchers have issued a new warning about CT scans and cancer. The risk of future cancer from CT scans has been analyzed, showing the potential for "tens of thousands" of cases of cancer that could occur in the future.

The analysis revealed variables in the dose of radiation delivered during CT scans in four institutions studied. Radiation doses from CT scans varies depending on what part of the body is being scanned. CT scans of the head, chest, abdomen, and pelvis pose the greatest cancer risk among the 35 to 54 year old age group.

Though the risk of cancer from CT scans is small, the authors say, because of the large number of persons exposed annually, even small risks could translate into a considerable number of future cancers."

Looking at CT scan radiation in four different institutions revealed variables that averaged 13 fold between the highest and lowest dose.

University of California researchers estimated the risk of cancer from CT scans in 1,119 patients in 2008. One in 600 men who undergo CT scan of the heart (coronary angiography) at age 40 will develop cancer, as would one in 270 women. A CT scan of the head could cause cancer in one out of 8,100 women and 11,080 men.

Radiation doses during CT scans have increased over the last two decades in efforts to obtain detailed diagnoses. The authors say clinicians need to inform patients of the risk of cancer from CT scans, and carefully weigh the risks and benefits of the tests. Unnecessary CT scans should be avoided. In order to reduce the risk of cancer from CT scans, the authors also suggest standardized radiation dosing.

CT scans performed in 2007 could result in 29,000 cases of cancer in the future, according to an estimate from Amy Berrington de González and colleagues of the National Cancer Institute, Bethesda, Md. Fifteen percent of cancer from common CT scans would occur in children and teens. CT scans deliver 100 times the radiation dose of a standard chest x-ray. The study analyzes variable associated with CT scans and cancer risk.

Arch Intern Med. 2009;169[22]:2049-2050