TAILIEUCHUNG - Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries

Alterations in chromatin packing are not the only physical manifestations of cancer. A cluster of tumour cells will also usually display gross structural changes that pathologists use for diagnosis: cells look visibly deformed and are often enlarged, with swollen and misshapen nuclei; and the chromosomes are distri- buted eccentrically. In an attempt to study these chan- ges more accurately, researchers at ASU’s Biodesign Institute have developed an optical computerized tomography (CT) scan for individual cells. Like its better-known brain-scan counterpart, the cell version can create 3D images of single cells held in a gel-like suspension (figure 2), which eliminates the physical distortion inherent in mounting cells on slides to pro- duce 2D optical images | ARTICLES Articles Risk of cancer from diagnostic X-rays estimates for the UK and 14 other countries Amy Berrington de Gonzalez Sarah Darby Summary Background Diagnostic X-rays are the largest man-made source of radiation exposure to the general population contributing about 14 of the total annual exposure worldwide from all sources. Although diagnostic X-rays provide great benefits that their use involves some small risk of developing cancer is generally accepted. Our aim was to estimate the extent of this risk on the basis of the annual number of diagnostic X-rays undertaken in the UK and in 14 other developed countries. Methods We combined data on the frequency of diagnostic X-ray use estimated radiation doses from X-rays to individual body organs and risk models based mainly on the Japanese atomic bomb survivors with population-based cancer incidence rates and mortality rates for all causes of death using life table methods. Findings Our results indicate that in the UK about 0 6 of the cumulative risk of cancer to age 75 years could be attributable to diagnostic X-rays. This percentage is equivalent to about 700 cases of cancer per year. In 13 other developed countries estimates of the attributable risk ranged from 0 6 to 1 8 whereas in Japan which had the highest estimated annual exposure frequency in the world it was more than 3 . Interpretation We provide detailed estimates of the cancer risk from diagnostic X-rays. The calculations involved a number of assumptions and so are inevitably subject to considerable uncertainty. The possibility that we have overestimated the risks cannot be ruled out but that we have underestimated them substantially seems unlikely. Lancet 2004 363 345-51 See Commentary page 340 Cancer Research UK Epidemiology Unit A Berrington de Gonzalez DPhil and Clinical Trial Service Unit and Epidemiological Studies Unit Prof S Darby PhD University of Oxford Radcliffe Infirmary Oxford UK Correspondence to Dr Amy Berrington de Gonzalez Cancer .

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