Cardiac CT Scanning Cancer Risk Shown To Be Overstated

Radiology and cardiovascular investigators have revealed that the risk of cancer from exposure to radiation during computed tomography (CT) imaging for cardiovascular disease has been overstated, and that new estimates are several times lower than previously published conclusions.

The researchers, from the Medical University of South Carolina (MUSC; Charleston, USA), presented their findings at the American Heart Association's meeting in New Orleans, LA, USA, in November 2008. In earlier published research, different researchers concluded the risk of cancer from radiation exposure during CT imaging for cardiovascular disease was approximately 1 in 114, but the new study suggests the risk is 1 in 1,000.

U. Joseph Schoepf, M.D. and colleagues from MUSC claim earlier studies assessing lifetime risks of cancer from radiation in cardiac CT are based on unreliable models of patients who undergo CT for cardiovascular disease. In conducting his study, Dr. Schoepf studied 104 consecutive patients undergoing 64-slice cardiac CT at the Medical University of South Carolina. Most of the patients were male with an average age of 59 and median weight of 202 pounds. The research team converted organ radiation doses into risk using a previously published and validated measure. Cancer risks were adjusted taking into account patient sex, age, and weight; the latter being an often-neglected factor influencing radiation risk.

The new risk in this patient population, which mirrors more closely to the typical patients who receive cardiac CT, was 1 in 1,000, according to Dr. Schoepf. "Thus, in a real-life clinical patient group, the realistic risk of radiation induced cancer from cardiac CT is substantially lower than previously reported for general populations,” Dr. Schoepf said.

Dr. Schoepf added that radiation exposure is an important issue and patients need to talk to their physicians before undergoing any tests that exposes them to radiation to ensure the test is appropriate and the patient fits under patient selection guidelines published by the American Heart Association (Dallas, TX, USA) and the American College of Radiology (Reston, VA, USA).

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