A new study lessens concerns that radiation exposure from diagnostic CT scans — a medical procedure that has become more common in the past decade — has substantially increased cancer incidence. Presented at the annual meeting of the Radiological Society of North America yesterday, the retrospective study was conducted by researchers from Stanford University who analyzed the records of 10 million patients’ Medicare claims from 1998 to 2005 to determine their radiation exposure from CT scans and correlated those exposures with the subsequent incidence of cancer. While the absolute amount of radiation exposure from CT scans doubled in the last three years of the study, the associated cancer incidence only rose to 0.04 percent from 0.02 percent. This is approximately a 20-fold decrease from previous estimates.
While these results may be considered positive, the study still supports ACSH’s Dr. Gilbert Ross’ view that there is no clear rationale for routine annual CT scans. In a 2007 op-ed on avoiding unnecessary CT scans, he noted:
So how afraid of CT scans should we be? The simple dictum applies: if a doctor believes that you need a CT scan, by all means get one. The benefit-risk equilibrium is strongly -- I'd say completely -- dictated by the medical necessity of getting the test. If a substantial diagnostic dilemma exists, or a need to evaluate the results of a therapy, don't worry about the small dose of radiation involved in one CT scan. The concern should kick in when considering a "whole-body" scan for no particular reason ... It is true that occasionally a "screening" CT scan may reveal a hidden danger that can be treated in time to avert disaster. However, all too often, an insignificant nodule or calcification (an "incidentaloma," in medicalese) will lead down the path of unnecessary surgery and its consequences. Often, a different type of diagnostic test using no radiation would suffice -- e.g., using ultrasound to detect a potentially lethal aneurysm in the abdominal or thoracic aorta.