The risk of developing cancer from computed tomography (CT) scans appears to be significantly lower than previous estimates of 1.5% to 2% in the general population, conclude researchers who analyzed eight years’ worth of Medicare claims to assess CT usage.

Based on information from more than 10 million Medicare records from 1998-2001 and 2002-2005, investigators Aabed Meer—an MD candidate at Stanford University—and colleagues estimated radiation-induced cancer rates at 0.02% to 0.04% of the study population. Mr. Meer noted in a statement announcing his team’s findings that the elderly Medicare population is exposed to the highest amount of ionizing radiation per capita. The number of patients receiving radiation doses in the low and high ranges both approximately doubled in the 2002-2005 cohort compared with the 1998-2001 cohort.

“However, our estimates of CT-related cancer incidences are still very low, even though our study focuses on the very group of patients (older adults) receiving the most CT examinations,” the authors write in an abstract (http://rsna2010.rsna.org/program/event_display.cfm?em_id=9004767) presented at the annual meeting of the Radiological Society of North America, held in Chicago November 28-December 3 (http://rsna2010.rsna.org/index.cfm). 

The researchers do point out that although the risk of CT-related cancers appears to be low, the increasing reliance on CT scans underscores the importance of monitoring CT utilization and its consequences.