| It has been estimated by experts that up to 2 percent | | | | these otherwise preventable cancers would manifest |
| of all cancer cases are caused by exposure to | | | | as leukemia in women. |
| medical x-ray tests. Although it is believed that there is | | | | Unfortunately, there is currently no scientific consensus |
| no completely safe level of exposure to x-rays, it is | | | | regarding the clinical benefit, if any, of using CT |
| well known that exposure to increasing doses of | | | | scanners to detect coronary artery disease in |
| x-rays, as well as undergoing repeated x-ray | | | | asymptomatic patients, as there is no high level clinical |
| examinations, increases the risk of cancer formation. | | | | research data available to prove that this screening |
| The increasing use of CT scanners (which can | | | | approach reduces cardiac disease events, or |
| expose patients to significant doses of radiation) to | | | | cardiac-associated deaths. Therefore, all that can be |
| screen asymptomatic patients for coronary artery | | | | confidently said, at this time, about the routine use of |
| disease has been a source of growing concern | | | | CT scans to screen for coronary artery disease is |
| among many cancer experts. While the detection of | | | | that it is, undoubtedly, associated with a small but not |
| coronary artery calcifications and coronary artery | | | | insignificant risk of otherwise preventable cancers. |
| narrowing (stenosis) on multi-detector CT scanners | | | | Moreover, when you consider that the authors of this |
| are powerful predictors of future cardiac disease | | | | study used very conservative estimates regarding |
| events, it remains unclear, at this time, whether or not | | | | absorbed radiation doses in patients undergoing |
| this approach to coronary artery disease screening | | | | coronary artery screening, the actual cancer risk |
| offers any significant clinical benefits to otherwise | | | | associated with many of cardiac screening CT scan |
| asymptomatic patients. | | | | protocols in current use is probably significantly higher |
| A newly published clinical research study, which | | | | than what this study predicts. |
| appears in the current issue of the Annals of Internal | | | | In my own case, I underwent two separate CT scans, |
| Medicine, further quantifies the potential cancer risk | | | | to assess for both coronary artery calcifications and |
| associated with the use CT scans to screen for | | | | coronary artery narrowing (stenosis), as part of a "VIP |
| coronary artery disease. | | | | Physical" in 2006. At the time, there was great |
| Because there are no nationally standardized protocols | | | | enthusiasm for the routine use of CT scanners for this |
| for CT scan cardiac screening examinations, the | | | | purpose. However, based upon the available data |
| authors of this study considered several commonly | | | | (including the data from this study), I have recently |
| used CT scan protocols, and then calculated the actual | | | | decided that I will not undergo any additional heart |
| dose of radiation delivered to patients with each of | | | | screening CT scans until and unless compelling clinical |
| these scan protocols. Using long-term data derived | | | | data comes along to suggest that the benefit from |
| from Japanese atomic bomb survivors, the | | | | such scans outweighs their potential risks. If you have |
| researchers then estimated the added cancer risk to | | | | been considering undergoing a routine cardiac |
| patients receiving coronary artery screening CT scans. | | | | screening CT scan, my advice is to first discuss the |
| One important (and concerning) finding from this study | | | | data contained in this clinical study with your Internist or |
| is that radiation doses delivered to patients vary by | | | | Cardiologist, and ask them to clarify both the potential |
| more than 10-fold among the different CT scan | | | | risks and benefits, in your particular case, of undergoing |
| protocols in common use throughout the United States. | | | | a coronary artery screening CT scan. |
| Based upon existing screening recommendations, the | | | | Meanwhile more research is needed to clarify what, if |
| authors calculated the added cancer risk associated | | | | any, health benefits can be reasonably claimed for |
| with adult patients undergoing coronary artery | | | | routine coronary artery screening CT scans in |
| screening CT scans every 5 years between the ages | | | | asymptomatic patients. Finally, in view of the immense |
| of 45 and 75 years for men, and every 5 years | | | | variation in radiation doses associated with the various |
| between the ages of 55 and 75 years for women. | | | | CT scanning protocols in common use today, |
| Using the very conservative assumption that all | | | | professional radiology societies and boards should |
| patients are exposed to a dose of radiation equivalent | | | | quickly work to reach a consensus on standardizing |
| to the average of all commonly used CT scan | | | | these protocols in such a way that unnecessary |
| protocols, the authors calculated that the lifetime | | | | radiation exposure is minimized. |
| increased incidence of cancer was 4.2 new cases of | | | | By, Robert A. Wascher, MD, FACS |
| cancer per 10,000 men, and 6.2 new cases of cancer | | | | Updated: 07/26/2009 |
| per 10,000 women. Based upon the known effects of | | | | ____ |
| radiation to the organs contained in the chest area, | | | | The information in this column is intended for |
| approximately 71 percent of the cancer cases caused | | | | informational purposes only, and does not constitute |
| by CT scans of the heart would be in the form of lung | | | | medical advice or recommendations by the author. |
| cancer, while 20 percent of these "excess" cancers | | | | Please consult with your physician before making any |
| would be breast cancers induced in women. Another | | | | lifestyle or medication changes, or if you have any |
| 12 percent of these radiation-induced cancers would | | | | other concerns regarding your health. |
| be in the form of leukemia in men, while 4 percent of | | | | |