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There is a new article in JAMA published this week that attempts to make estimates for the risk of development of malignancy in patients as a result of a single coronary artery CT scan (CTCA) for evaluation of possible coronary artery disease. The is an especially prescient article for emergency medicine physicians given the large number of chest pain complaints that present to EDs and also specifically at our institution since we have now started to perform this test (not to mention that one of the co-authors of the paper is based at our medical center).

Briefly, the paper uses statistical risk modeling (called the Monte Carlo method, more about that later) to make estimates about the risk of development of malignancy as correlated with the level of radiation exposure from each of 4 different type of CTCAs and the age of the patient when the scan was done. Unsurprisingly, the risk of cancer development increased the earlier that the scan was done, but somewhat surprisingly the curve was quite concerning for patients dosed with radiation early in life. Particulary concerning were young females (20 years old) who had twice the RR and thrice the RR of their 40-year old and 60-year old counterparts, respectively, for the development of cancer during their lifetime.

Regarding the statistics, what is interesting is the Monte Carlo method was used for statistical modeling. This is the same mathematical modeling used for risk modeling in the insurance and financial industries, and the results bear striking resemblance. Much as the power of interest compounded over time is the great wealth creator, it seems that the effect of early radiation compounded over time is similarly potent for causing malignancy in later life.

This study is certainly limited in that it studied no real patients and simply extrapolated data from mathematical models. Further the authors did not compare this test with others that may employ similar or slightly lesser amounts of radiation. That being said, it should give pause that all the imaging that is ordered is not without risk, and even if that risk is small for the individual, the population-based risk — given the fantastic numbers in question — is not small indeed.

Posted on Tuesday, July 24th, 2007 at 2:21 am by Sohan. Filed under Oncology, Radiology, ACS.
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