The Archives of Internal Medicine reported on two studies estimating that the radiation exposure from the 72 million CT scans ordered in 2007 alone will result in 15,000 additional cancer deaths twenty to thirty years down the road.
An editorial in the Archives pointed out that there is an eight-fold difference in CT scan use around the country with no better outcomes where more scans are done.
Is there evidence that a CT saves lives? No. No diagnostic/laboratory test ever has. This is not what it does.
Diagnostic/laboratory tests are judged by accuracy and reproducibility and never by their effect upon treatment outcomes. Most tests used today have comparable "sensitivities" and "specificities."
CT scans were not approved because they saved lives in a controlled clinical trial that compared the outcome of patients who received care with or without the benefit of a CT scan. They were approved because their performance characteristics (sensitivity/specificity) are reproducible, favorable and provide information to treating physicians.
In cancer medicine, no test in oncology has ever been shown in prospective randomized clinical trials to improve patient outcomes. The existing standard has always been the "accuracy" of the test. This is true for every single test used in cancer medicine, from estrogen receptors to panels of immunohistochemical stains (IHC) to diagnosing and classifying tumor to Her2/neu and CA-125 to cell culture assays to MRI's, CT Scans, Pet Scans and so on.
Even when you get to the new genetic/molecular tests, the validation standard that private insurance companies is accepting is "accuracy" and not "efficacy." The essential "proof" is that all they have to do for these tests is that the test has a useful degree of "accuracy," not that the use of the diagnostic test improves clinical outcomes.
A cardiac CT provides anatomic information regarding the presence or absence of blockages in coronary arteries. Such findings alone do not determine whether or not a patient requires an invasive procedure such as an angiogram or angioplasty/stent. Such decisions should be based on physiologic indicators such as presence of angina or, more importantly, an abnormal stress test. A cardiac CT by itself will never be proven to save lives. However, it is yet another tool in the arsenal that must be used properly.
In cancer medicine, the CT is used to follow the size of the patient's tumor while the patient is receiving repeated courses of chemotherapy to determine whether or not the treatment is working and whether or not different drugs should be given, instead. This is an entirely unproven benefit, and were appropriate studies ever to be performed, there wouldn't be any measurable benefit at all, in terms of improving patient response to chemotherapy or patient survival with chemotherapy.
CT Scans and Cancer Risk: Been There, Done That
http://www.cancer.org/aspx/blog/Comments.aspx?id=336
Projected Cancer Risks From Computed Tomographic Scans Performed in the United States in 2007
These detailed estimates highlight several areas of CT scan use that make large contributions to the total cancer risk, including several scan types and age groups with a high frequency of use or scans involving relatively high doses, in which risk-reduction efforts may be warranted.
http://archinte.ama-assn.org/cgi/con...ll/169/22/2071
Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer
Radiation doses from commonly performed diagnostic CT examinations are higher and more variable than generally quoted, highlighting the need for greater standardization across institutions.
http://archinte.ama-assn.org/cgi/con...9/22/2078?home