New studies document long-term cancer risk of medical CT-scanning

Two new studies published in the Archives of Internal Medicine constitute a startling warning of the risk of cancer posed by the "explosion" of CT-scanning since 1993.  Performed by the National Cancer Institute and the University of California, San Francisco, they document the increased risk of developing cancer and also the lack of established guidelines and uniformity in associated radiation dosing.

The authors of the risk study identified lung cancer as the most common radiation-associated metastatic disease, followed by colon cancer and leukemia.  They predict that with the three-fold increase in CT-scanning over the past decade, we will experience 29,000 new cancer diagnoses and 15,000 additional deaths, annually, with a two percent over-all cancer occurrence.  (Doctors currently diagnose 1.4 million cancer cases, annually.)

72 million CT scans were performed in the U.S. in 2007, and UCSF researchers found a 13-fold variation in radiation dosage.  The U.S. FDA only issued interim regulations on exposure monitoring this December after documenting 250 cases of injury caused by excess exposure in October and November.

It appears clear that the heatlh risk diminishes with age, posing the greater risk to young people.  For example, the risk may be as high as 1 in 80 for young persons being CT-scanned for particular conditions, while the risk virtually disappears among the elderly.  Risks also affect women more commonly, as they are significantly more likely to be CT-scanned.  The studies relied upon Medicare data, a review of CT scan procedures on 1100 Bay-area patients over 5 months, private insurance data and a telephone survey.