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电离辐射是由直接或间接电离粒子或二者混合组成的辐射，能使受作用物质发生电离现象的辐射，即波长小于100nm的电磁辐射。虽然高剂量电离辐射与乳腺癌风险增加有关，但是长期低剂量电离辐射暴露与乳腺癌风险之间的相关性尚不清楚。 2016年9月13日，英国《自然》旗下《英国癌症杂志》在线发表美国加利福尼尤利卡亚广软国际、国家癌症研究所、马里兰罗克维尔信息管理服务、明尼苏达大学的美国放射技师研究报告。 在该研究中，66915位女性技师有1922位于1983～2005年自我报告首次诊断原发癌症；83538位女性队列有586位于1983～2008年间死于乳腺癌。基于工作史、历史数据、19世纪70年代中期之后个人胶片测量等信息，评估参与者的职业性乳腺照射剂量。 结果发现，较高的乳腺照射剂量会增加乳腺癌发生风险，当照射剂量为100mGy时，额外相对风险为0.07（95%置信区间：-0.005～0.19）。1930年之前出生的放射技师，这两者之间的相关性更强烈，当照射剂量为100mGy时，额外相对风险为0.16（95%置信区间：0.03～0.39）；此外，死亡率方面与患病率有相似的相关模式；1930年之前出生的放射技师，照射剂量与死亡率之间的相关性更强烈。 因此，乳腺受到职业性电离辐射暴露与乳腺癌风险呈正相关，尤其是1930年之前出生、1950年之前工作的女性，两者的相关性尤其强烈，因为1950年之前的年职业性辐射暴露（37mGy）高于这个时间点之后（1.3mGy）。不过，由于1960年之前职业剂量估算的不确定性和可能的系统误差，应谨慎对待这些结果。 Br J Cancer. 2016 Sep 13. [Epub ahead of print] Breast cancer risk and protracted low-to-moderate dose occupational radiation exposure in the US Radiologic Technologists Cohort, 1983-2008. Preston DL, Kitahara CM, Freedman DM, Sigurdson AJ, Simon SL, Little MP, Cahoon EK, Rajaraman P, Miller JS, Alexander BH, Doody MM, Linet MS. Hirosoft International, Eureka, CA, USA; National Cancer Institute, Rockville, MD, USA; Information Management Services Inc., Rockville, MD, USA; University of Minnesota, Minneapolis, MN, USA. BACKGROUND: Although high-dose ionising radiation is associated with increased breast cancer risks, the association with protracted low-dose-rate exposures remains unclear. The US Radiologic Technologist study provides an opportunity to examine the association between low-to-moderate dose radiation and breast cancer incidence and mortality. METHODS: One thousand nine hundred and twenty-two self-reported first primary cancers were diagnosed during 1983-2005 among 66915 female technologists, and 586 breast cancer deaths occurred during 1983-2008 among 83538 female cohort members. Occupational breast dose estimates were based on work histories, historical data, and, after the mid-1970s, individual film badge measurements. Excess relative risks were estimated using Poisson regression with birth cohort stratification and adjustment for menopause, reproductive history, and other risk factors. RESULTS: Higher doses were associated with increased breast cancer incidence, with an excess relative risk at 100mGy of 0.07 (95% confidence interval (CI): -0.005 to 0.19). Associations were strongest for technologists born before 1930 (excess relative risk at 100mGy=0.16; 95% CI: 0.03-0.39) with similar patterns for mortality among technologists born before 1930. CONCLUSIONS: Occupational radiation to the breast was positively associated with breast cancer risk. The risk was more pronounced for women born before 1930 who began working before 1950 when mean annual doses (37mGy) were considerably higher than in later years (1.3mGy). However, because of the uncertainties and possible systematic errors in the occupational dose estimates before 1960, these findings should be treated with caution. PMID: 27623235 DOI: 10.1038/bjc.2016.292 |
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