Boice J D, Mandel J S, Doody M M
Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892, USA.
JAMA. 1995 Aug 2;274(5):394-401.
To evaluate the risk of breast cancer among women occupationally exposed to ionizing radiation.
Case-control study.
A health survey of 105,385 women radiologic technologists certified by the American Registry of Radiologic Technologists since 1926. Among 79,016 respondents, 600 breast cancer cases were identified. Each of 528 eligible subjects with breast cancer was matched to five control subjects based on age, year of certification, and follow-up time.
Relative risk (RR) estimated as the relative odds ratio for breast cancer over categories of years worked as a radiologic technologist and according to personal and occupational exposure characteristics.
Study subjects had been certified for a mean of 29 years; 63.8% of cases and 62.6% of controls worked as radiologic technologists for 10 years or more. Significant increased risks for breast cancer were associated with early age at menarche (for < 11 years of age: RR = 1.79; 95% confidence interval [CI], 1.09 to 2.94), nulliparity (RR = 1.36; 95% CI, 1.04 to 1.78), first-degree relative with history of breast cancer (RR = 2.07; 95% CI, 1.56 to 2.74), prior breast biopsy (RR = 1.53; 95% CI, 1.17 to 2.00), alcohol consumption (for > 14 alcoholic drinks per week: RR = 2.12; 95% CI, 1.06 to 4.27), thyroid cancer (RR = 5.36; 95% CI, 1.64 to 17.5), hyperthyroidism (RR = 1.66; 95% CI, 1.02 to 2.71), and residence in the northeastern United States (RR = 1.66; 95% CI, 1.19 to 2.30). Jobs involving radiotherapy, radioisotopes, or fluoroscopic equipment, however, were not linked to breast cancer risk, nor were personal exposures to fluoroscopy or multifilm procedures. Use of birth control pills, postmenopausal estrogens, or permanent hair dyes also were not risk factors. Based on dosimetry records for 35% of study subjects, cumulative exposures appeared low. Among women who worked more than 20 years, the RR for breast cancer was 1.13 (95% CI, 0.79 to 1.64).
More than 50% of the reported breast cancers could be explained by established risk factors. Employment as a radiologic technologist, however, was not found to increase the risk of breast cancer. The contribution of prolonged exposure to relatively low doses of ionizing radiation to breast cancer risk was too small to be detectable at this time.
评估职业性接触电离辐射的女性患乳腺癌的风险。
病例对照研究。
对自1926年以来由美国放射技师登记处认证的105,385名女性放射技师进行健康调查。在79,016名受访者中，确诊600例乳腺癌病例。528名符合条件的乳腺癌受试者中的每一位都根据年龄、认证年份和随访时间与五名对照受试者进行匹配。
相对风险（RR），估计为作为放射技师工作的年份类别以及根据个人和职业暴露特征患乳腺癌的相对比值比。
研究对象的认证平均时长为29年；63.8%的病例和62.6%的对照作为放射技师工作了10年或更长时间。乳腺癌风险显著增加与初潮年龄早（初潮年龄<11岁：RR = 1.79；95%置信区间[CI]，1.09至2.94）、未生育（RR = 1.36；95% CI，1.04至1.78）、有乳腺癌病史的一级亲属（RR = 2.07；95% CI，1.56至2.74）、既往乳腺活检（RR = 1.53；95% CI，1.17至2.00）、饮酒（每周饮用超过14杯酒精饮料：RR = 2.12；95% CI，1.06至4.27）、甲状腺癌（RR = 5.36；95% CI，1.64至17.5）、甲状腺功能亢进（RR = 1.66；95% CI，1.02至2.71）以及居住在美国东北部（RR = 1.66；95% CI，1.19至2.30）有关。然而，涉及放射治疗、放射性同位素或荧光透视设备的工作与乳腺癌风险无关，个人接受荧光透视或多片摄影检查也与乳腺癌风险无关。使用避孕药、绝经后雌激素或永久性染发剂也不是风险因素。根据35%研究对象的剂量测定记录，累积暴露量似乎较低。在工作超过20年的女性中，患乳腺癌的RR为1.13（95% CI，0.79至1.64）。
报告的乳腺癌病例中超过50%可由既定风险因素解释。然而，未发现从事放射技师工作会增加患乳腺癌的风险。此时，长期暴露于相对低剂量的电离辐射对乳腺癌风险的影响太小，无法检测到。
