Does iodinated contrast medium amplify DNA damage during exposure to radiation

Abstract

There is a recognized increased risk of cancer following exposure of humans to ionizing radiation; this is felt to be most likely due to damage to DNA strands during exposure. Damage to DNA strands can be demonstrated microscopically following exposure to X-rays, and new evidence is emerging that this effect may be compounded by administration of iodinated contrast agents. INTRODUCTIONIt is widely accepted that there is an increased risk of cancer following exposure to ionizing radiation. The primary source of information is the Life Span Study, an epidemiological study of survivors of the atomic bombs at Hiroshima and Nagasaki. There were an excess number of deaths from leukaemia in the early follow-up years. Most recent figures published in 2011 indicate an excess relative risk for solid tumours of between 0.5 and 0.8 for doses between 5 and 200 mGy. 1 A study published in 2004 estimated that 0.9% of the cumulative cancer risk to individuals in the USA could be attributable to diagnostic X-ray exposure, equivalent to 5695 cases of newly diagnosed cancer per annum.2 Diagnostic X-rays are the largest man-made source of radiation exposure. More complex examinations, and interventional procedures are increasing in number and average dose annually throughout the developed world. In the UK in 2008, CT accounted for 7% of the total number of medical and dental examinations but 68% of their resultant total collective dose.

Enhanced radiation damage caused by iodinated contrast agents during CT examination

“…Over the last few decades the use of contrast agent had increased enormously by 800% [3]. There were comprehensive evidences in the literature that the presence of iodinate contrast agent during X-ray examinations could induce the amount of DNA damages in blood lymphocytes [6,13,14]. However, it is still unclear if the cytotoxic effects observed after ICA administration result from increased initial damage yields, from a reduced damage repair capacity, or from cytotoxic effects of ICA [15].…”

Enhanced radiation dose and DNA damage associated with iodinated contrast media in diagnostic X-ray imaging

“…1 There are also concerns, however, that contrast media may also increase the cancer risks from X-ray exposures, by increasing the DNA damage from a given radiation exposure. 2,3 Since the late 1970s, studies have demonstrated increased damage, by up to several hundred percent, to blood cells following the administration of intravenous ICM during diagnostic X-ray and interventional fluoroscopy exposures, compared with unenhanced exposures. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The results of other studies in which larger-than-expected levels of DNA damage were reported 19,20 could, potentially, also be explained by the effect of ICM use.…”

The impact of iodinated contrast media on intravascular and extravascular absorbed doses in X-ray imaging: A microdosimetric analysis

“…Iodinated contrast media (ICM) are frequently used in diagnostic x-ray imaging, including around 50% of CT scans [1], to improve visualization of blood vessels and other structures. In addition to well-known chemo/osmotoxic side effects, including allergic reactions and kidney damage [2], concerns have also been raised that contrast media may increase cancer risks from x-ray exposures [3,4]. Recently, we reviewed around four decades-worth of research investigating the radiation doses and associated DNA damage for ICM-enhanced, versus unenhanced x-ray exposures [5].…”