University of Rochester School of Medicine and Dentistry, Department of Community and Preventive Medicine, 601 Elmwood Avenue, Box 644, Rochester, New York, USA.
Cancer Epidemiol Biomarkers Prev. 2010 Jan;19(1):48-58. doi: 10.1158/1055-9965.EPI-09-0520.
Radiotherapy during childhood increases long-term cancer risk, but the risk from radiation as a result of relatively higher dose diagnostic procedures remains less well known. This study, which evaluates breast cancer incidence in a cohort treated with "lower dose" chest radiotherapy over 50 years ago, can assist with estimating lifetime breast cancer risk in young children exposed to radiation from procedures such as chest computed tomography (CT) or treatment with recent "lower dose" chest radiotherapy protocols.
A population-based, longitudinal cohort of subjects exposed to thymic irradiation during infancy from 1926 to 1957 and of their unexposed siblings was re-established. Previously followed until 1987, we resurveyed cohort members from 2004 to 2008. Poisson regression models compared breast cancer incidence rates between women in the cohort by treatment and dose category groups.
Breast cancer occurred in 96 treated (mean breast dose, 0.71 Gy) and 57 untreated women during 159,459 person-years of follow-up. After adjusting for attained age and treatment/birth cohort, the rate ratio was 3.01 (2.18-4.21). The adjusted excess relative risk per Gy was 1.10 (95% confidence interval, 0.61-1.86). Traditional breast cancer risk factors did not contribute significantly to multivariate model fit.
Our results show that at radiation doses between those received by the breast from chest CT and cancer therapy during early childhood, breast cancer incidence rates remain elevated >50 years after exposure. This implies that increased breast cancer risk will remain a lifelong concern in females treated during childhood with currently reduced radiotherapy doses and for infants receiving multiple chest CTs.
儿童时期的放射治疗会增加长期癌症风险，但由于相对较高剂量的诊断程序而导致的风险知之甚少。本研究评估了 50 多年前接受“低剂量”胸部放射治疗的队列中的乳腺癌发病率，有助于估计因胸部 CT 等程序或最近的“低剂量”胸部放射治疗方案而暴露于辐射的幼儿的终生乳腺癌风险。
重新建立了一个基于人群的、纵向队列，该队列中的受试者在婴儿期（1926 年至 1957 年）接受过胸腺照射，并且有未暴露的兄弟姐妹。此前随访至 1987 年，我们在 2004 年至 2008 年重新调查了队列成员。泊松回归模型比较了队列中女性按治疗和剂量类别分组的乳腺癌发病率。
在 159459 人年的随访中，96 名接受治疗（平均乳房剂量为 0.71Gy）和 57 名未接受治疗的妇女发生了乳腺癌。在调整了获得年龄和治疗/出生队列后，比率比为 3.01（2.18-4.21）。每 Gy 的调整后的超额相对风险为 1.10（95%置信区间，0.61-1.86）。传统的乳腺癌危险因素对多变量模型拟合没有显著贡献。
我们的研究结果表明，在胸部 CT 照射和儿童早期癌症治疗中乳房接受的辐射剂量之间，暴露后 50 多年，乳腺癌发病率仍处于较高水平。这意味着，对于目前接受减少放射治疗剂量的儿童和多次接受胸部 CT 检查的婴儿，乳腺癌风险增加将成为终生关注的问题。
