Doody Michele Morin, Freedman D Michal, Alexander Bruce H, Hauptmann Michael, Miller Jeremy S, Rao R Sowmya, Mabuchi Kiyohiko, Ron Elaine, Sigurdson Alice J, Linet Martha S
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland 20892-7238, USA.
Cancer. 2006 Jun 15;106(12):2707-15. doi: 10.1002/cncr.21876.
Studies of atomic bomb survivors and medically exposed populations have demonstrated an increased risk of breast cancer associated with acute or protracted, intermediate-dose or high-dose, ionizing radiation; however, the risks associated with low-dose and low-dose-rate (protracted) exposures are less certain.
The authors evaluated incident breast cancer risks from 1983 to 1998 according to employment characteristics and a 4-level proxy index for cumulative radiation exposure based on 2 mail surveys among 56,436 U.S. female radiologic technologists who were certified from 1925 to 1980, adjusting for established breast cancer risk factors.
During follow-up, 1050 new breast cancer diagnoses were ascertained. Compared with radiologic technologists who began working in 1970 or later, adjusted breast cancer risks for those who first worked in the 1960s, 1950s, 1940s, from 1935 to 1939, and before 1935 were 1.0 (95% confidence interval [CI], 0.8-1.2), 1.2 (95% CI, 0.9-1.6), 1.0 (95% CI, 0.7-1.5), 1.8 (95% CI, 1.0-3.2), and 2.9 (95% CI, 1.3-6.2), respectively. The risk rose with the number of years worked before 1940 (P value for trend = .002) and was elevated significantly among those who began working before age 17 years (relative risk, 2.6; 95% CI, 1.3-5.1; 10 women) but was not related to the total years worked in the 1940s or later. Compared with technologists who had a Level 1 (minimal) proxy index for cumulative radiation exposure, breast cancer risks were 1.0 (95% CI, 0.9-1.2), 1.0 (95% CI, 0.7-1.3), and 1.5 (95% CI, 1.0-2.2), respectively, for technologists who had Level 2, Level 3, and Level 4 (highest) exposure.
Breast cancer risk was elevated significantly in female radiologic technologists who experienced daily low-dose radiation exposures over several years that potentially resulted in appreciable cumulative exposure. The increased risk for total years worked before 1940, but not later, was consistent with decreasing occupational radiation exposures, improvements in radiation technology, and more stringent radiation protection standards over time.
对原子弹爆炸幸存者和医疗受照人群的研究表明，急性或长期、中等剂量或高剂量电离辐射会增加患乳腺癌的风险；然而，低剂量和低剂量率（长期）照射相关的风险尚不确定。
作者根据就业特征以及基于对1925年至1980年获得认证的56436名美国女性放射技师进行的两次邮件调查得出的4级累积辐射暴露替代指标，评估了1983年至1998年期间乳腺癌的发病风险，并对已确定的乳腺癌风险因素进行了调整。
在随访期间，共确诊1050例新发乳腺癌。与1970年或之后开始工作的放射技师相比，20世纪60年代、50年代、40年代、1935年至1939年以及1935年之前首次工作的放射技师的调整后乳腺癌风险分别为1.0（95%置信区间[CI]，0.8 - 1.2）、1.2（95% CI，0.9 - 1.6）、1.0（95% CI，0.7 - 1.5）、1.8（95% CI，1.0 - 3.2）和2.9（95% CI，1.3 - 6.2）。风险随着1940年之前工作的年数增加而上升（趋势P值 = 0.002），在17岁之前开始工作的人群中风险显著升高（相对风险，2.6；95% CI，1.3 - 5.1；10名女性），但与20世纪40年代或之后的总工作年数无关。与累积辐射暴露替代指标为1级（最低）的技师相比，累积辐射暴露替代指标为2级、3级和4级（最高）的技师的乳腺癌风险分别为1.0（95% CI，0.9 - 1.2）、1.0（95% CI，0.7 - 1.3）和1.5（95% CI，1.0 - 2.2）。
在经历了数年每日低剂量辐射暴露、可能导致可观累积暴露的女性放射技师中，乳腺癌风险显著升高。1940年之前而非之后工作总年数增加导致风险上升，这与职业辐射暴露的减少、辐射技术的改进以及随着时间推移更严格的辐射防护标准是一致的。
