Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Rockville, MD, USA.
Am J Epidemiol. 2013 Apr 15;177(8):800-9. doi: 10.1093/aje/kws315. Epub 2013 Mar 25.
Although diagnostic x-ray procedures provide important medical benefits, cancer risks associated with their exposure are also possible, but not well characterized. The US Radiologic Technologists Study (1983-2006) is a nationwide, prospective cohort study with extensive questionnaire data on history of personal diagnostic imaging procedures collected prior to cancer diagnosis. We used Cox proportional hazard regressions to estimate thyroid cancer risks related to the number and type of selected procedures. We assessed potential modifying effects of age and calendar year of the first x-ray procedure in each category of procedures. Incident thyroid cancers (n = 251) were diagnosed among 75,494 technologists (1.3 million person-years; mean follow-up = 17 years). Overall, there was no clear evidence of thyroid cancer risk associated with diagnostic x-rays except for dental x-rays. We observed a 13% increase in thyroid cancer risk for every 10 reported dental radiographs (hazard ratio = 1.13, 95% confidence interval: 1.01, 1.26), which was driven by dental x-rays first received before 1970, but we found no evidence that the relationship between dental x-rays and thyroid cancer was associated with childhood or adolescent exposures as would have been anticipated. The lack of association of thyroid cancer with x-ray procedures that expose the thyroid to higher radiation doses than do dental x-rays underscores the need to conduct a detailed radiation exposure assessment to enable quantitative evaluation of risk.
尽管诊断性 X 射线程序提供了重要的医学益处，但与之相关的癌症风险也是可能的，但尚未得到充分描述。美国放射技师研究（1983-2006 年）是一项全国性的前瞻性队列研究，对癌症诊断前收集的个人诊断成像程序史进行了广泛的问卷调查。我们使用 Cox 比例风险回归来估计与选定程序数量和类型相关的甲状腺癌风险。我们评估了年龄和每种程序类别的首次 X 射线程序的日历年的潜在修饰作用。在 75494 名技师（130 万人年；平均随访时间= 17 年）中诊断出 251 例甲状腺癌（n=251）。总体而言，除了牙科 X 射线外，没有明确证据表明诊断性 X 射线与甲状腺癌风险相关。我们观察到，每报告 10 次牙科射线照片，甲状腺癌风险增加 13%（危险比=1.13，95%置信区间：1.01，1.26），这主要是由于 1970 年前首次接受的牙科 X 射线引起的，但我们没有发现牙科 X 射线与甲状腺癌之间的关系与预期的儿童或青少年暴露有关。甲状腺癌与甲状腺暴露于比牙科 X 射线更高辐射剂量的 X 射线程序之间缺乏关联，这突出表明需要进行详细的辐射暴露评估，以便能够对风险进行定量评估。
