Akleyev Alexander, Deltour Isabelle, Krestinina Lyudmila, Sokolnikov Mikhail, Tsareva Yulia, Tolstykh Evgenia, Schüz Joachim
Urals Research Center for Radiation Medicine, Chelyabinsk, Russian Federation.
Chelyabinsk State University, Chelyabinsk, Russian Federation.
PLoS One. 2016 Aug 3;11(8):e0160372. doi: 10.1371/journal.pone.0160372. eCollection 2016.
Previous studies have shown that acute external in utero exposure to ionizing radiation can increase cancer risk. It is not known whether chronic exposure at low dose rates, including due to radionuclide intake, influences the lifetime risk of solid cancers in the offspring. The objective of this study was to investigate solid cancer risk after in utero irradiation.
Cancer incidence and mortality over a 60-year period (from January 1950 to December 2009) were analyzed in the Urals Prenatally Exposed Cohort (UPEC). The cohort comprised in utero exposed offspring of Mayak Production Association female workers and of female residents of Techa River villages. Some of the offspring also received postnatal exposure, either due to becoming radiation workers themselves or due to continuing to live in the contaminated areas of the Techa River. The mortality analyses comprised 16,821 subjects (601,372 person-years), and the incidence analyses comprised 15,813 subjects (554,411 person-years). Poisson regression was used to quantify the relative risk as a function of the in utero soft tissue dose (with cumulative doses up to 944.9 mGy, mean dose of 14.1 mGy in the pooled cohort) and the postnatal stomach dose for solid cancer incidence and mortality.
When a log-linear model was used, relative risk of cancer per 10 mGy of in utero dose was 0.99 (95% confidence interval (CI) = 0.96 to 1.01) based on incidence data and 0.98 (CI = 0.94 to 1.01) based on mortality data. Postnatal exposure to ionizing radiation was positively associated with the solid cancer risk in members of the UPEC, with a relative risk of 1.02 per 10mGy CI = 1.00 to 1.04).
No strong evidence was found that chronic low-dose-rate exposure of the embryo and fetus increased the risk of solid cancers in childhood or in adulthood. For both incidence and mortality, a tendency towards a decreased relative risk was noted with increasing doses to soft tissues of the fetus. Further follow-up will provide more precise radiation risk estimates of solid cancer as cohort members are approaching their 60s and cancer becomes more common.
既往研究表明，子宫内急性外部暴露于电离辐射可增加癌症风险。低剂量率慢性暴露，包括因摄入放射性核素所致的暴露，是否会影响后代实体癌的终生风险尚不清楚。本研究的目的是调查子宫内照射后实体癌风险。
对乌拉尔产前暴露队列（UPEC）中60年期间（从1950年1月至2009年12月）的癌症发病率和死亡率进行了分析。该队列包括马亚克生产协会女工和捷恰河村庄女性居民的子宫内暴露后代。部分后代还受到了产后暴露，这或是由于他们自己成为了辐射工作者，或是由于继续生活在捷恰河的污染区域。死亡率分析纳入了16,821名受试者（601,372人年），发病率分析纳入了15,813名受试者（554,411人年）。采用泊松回归来量化实体癌发病率和死亡率作为子宫内软组织剂量（累积剂量高达944.9 mGy，合并队列中的平均剂量为14.1 mGy）和产后胃部剂量的函数的相对风险。
当使用对数线性模型时，基于发病率数据，每10 mGy子宫内剂量的癌症相对风险为0.99（95%置信区间（CI）=0.96至1.01），基于死亡率数据为0.98（CI =0.94至1.01）。UPEC成员产后暴露于电离辐射与实体癌风险呈正相关，每10 mGy的相对风险为1.02（CI =1.00至1.04）。
未发现有力证据表明胚胎和胎儿的慢性低剂量率暴露会增加儿童期或成年期实体癌的风险。对于发病率和死亡率，随着胎儿软组织剂量增加，均注意到相对风险有降低的趋势。随着队列成员接近60岁且癌症变得更为常见，进一步随访将提供更精确的实体癌辐射风险估计。
