Abstract

Purpose

For 65 years the interpretation of the statistical association between the risk of cancer in a child and a prior diagnostic X-ray examination of the abdomen of the pregnant mother has been debated. The objections to a direct cause-and-effect explanation of the association vary in their strength, but one of the most notable grounds for controversy is the finding from the first and largest case-control study reporting the association, the Oxford Survey of Childhood Cancers (OSCC), of an almost uniformly raised relative risk (RR) for nearly all of the types of cancer that are most frequent in children. Here we compare the antenatal X-ray associations found in the OSCC for different types of childhood cancer with the results of all other case-control and case-cohort studies appropriately combined in meta-analyses, and we also review the findings of the few cohort studies that have been conducted.

Conclusions

From the case-control/case-cohort studies other than the OSCC there are consistent and clear elevations of risk for all types of childhood cancer combined, all leukemia, and all cancers except leukemia combined. This compatibility of the findings of the OSCC with those of the combined other studies is less clear, or effectively absent, when some categories containing smaller numbers of incident cases/deaths are considered, but lack of precision of risk estimates due to sparse data presents inferential challenges, although there is a consistent absence of an association for bone tumors. Further, more recent studies almost certainly address lower intrauterine doses, with an anticipated decrease in estimated risks, which could be misleading when comparisons involve a limited number of studies that are mainly from later years, and a similar problem arises when having to employ all types of antenatal X-ray exposures for a study because data for abdominal exposures are absent. The problem of low statistical power is greater for cohort studies, and this, together with other shortcomings identified in the studies, limits the interpretational value of results. The findings of non-medical intrauterine exposure studies are constrained by sparse data and make a limited contribution to an understanding of the association. Certain aspects of the various studies require a need for caution in interpretation, but overall, the appropriate combination of all case-control/case-cohort studies other than the OSCC lends support to the inference that low-level exposure to radiation in utero proportionally increases the risk of the typical cancers of childhood to around the same level.

中文翻译：

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与孕妇 X 光检查相关的儿童癌症类型综述

摘要

目的

65 年来，对儿童患癌症风险与先前对孕妇腹部进行诊断性 X 射线检查之间的统计关联的解释一直存在争议。对该关联的直接因果解释的反对意见在强度上各不相同，但最显着的争议理由之一是报告该关联的第一个也是最大的病例对照研究的发现，牛津儿童癌症调查(OSCC)，几乎所有儿童最常见的癌症类型的相对风险 (RR) 几乎一致升高。在这里，我们将 OSCC 中发现的不同类型儿童癌症的产前 X 射线关联与所有其他病例对照和病例队列研究的结果在荟萃分析中适当结合，

结论

从 OSCC 以外的病例对照/病例队列研究来看，所有类型的儿童癌症、所有白血病和除白血病以外的所有癌症的风险均一致且明显升高。OSCC 的结果与其他联合研究的结果的兼容性不太清楚，或实际上不存在，当考虑包含较少数量的事件病例/死亡的某些类别时，但由于数据稀疏而缺乏风险估计的精确度，这提供了推论挑战，尽管一直没有骨肿瘤的关联。此外，最近的研究几乎肯定会涉及较低的宫内剂量，预计风险会降低，当比较涉及主要来自晚年的有限数量的研究时，这可能会产生误导，并且在必须使用所有类型的产前 X 射线照射进行研究时会出现类似的问题，因为缺少腹部照射的数据。队列研究的低统计功效问题更大，这与研究中发现的其他缺点一起限制了结果的解释价值。非医学宫内暴露研究的结果受到稀疏数据的限制，对理解这种关联的贡献有限。各种研究的某些方面需要在解释时谨慎，但总体而言，除 OSCC 之外的所有病例对照/病例队列研究的适当组合为低水平辐射暴露的推断提供了支持在子宫内，儿童患典型癌症的风险成比例地增加到大约相同的水平。