External Beam Radiotherapy Department, National Cancer Institute, Santariskiu Str. 1, Vilnius LT-08406, Lithuania.
State Research Institute Center for Physical Sciences and Technology, Savanorių Ave. 231, Vilnius 02300, Lithuania.
Ecotoxicol Environ Saf. 2024 Sep 15;283:116789. doi: 10.1016/j.ecoenv.2024.116789. Epub 2024 Jul 26.
In the last three decades, an increase in thyroid cancer incidence has been observed worldwide, as well as in Lithuania. Although the rise was linked to overdiagnosis, the role of lifestyle and environmental factors, including exposure to ionizing radiation, cannot be excluded. In our retrospective study, we aimed to assess the association between the average age-specific thyroid dose due to the radioactive iodine uptake during childhood and adolescence from the Chernobyl fallout in Lithuania, and the trends of incidence of thyroid cancer from 1991 to 2015 in different regions. Averaged age-dependent thyroid doses were estimated for every municipality based on radioiodine activity in milk, reconstructed from available I activity measurements in the grass. Thyroid cancer incidence rates were calculated for the entire population and for two age at the time of exposure groups: 0-19 years and 0-9 years. Thyroid cancer relative risk (RR) was estimated for three municipality-specific thyroid dose (for 0-year-old babies) categories: less than 100 mGy (reference group), 100-199 mGy, and ≥200 mGy. Over the study period (1991-2015), a total of 5664 cases of thyroid cancer were registered in the entire Lithuanian population; 817 cases in the age group from 0 to 19 years at the time of the Chernobyl accident, and 266 cases in the age group from 0 to 9 years. Age-standardized thyroid cancer incidence rates have notably increased since 2000, peaked in 2009 (especially in females), and then slightly decreased and stabilized. The estimated average municipality-specific age-dependent thyroid doses ranged from 270 mGy in western Lithuania to 1.5 mGy in central and northern Lithuania. For the age group of 0-19 years at the time of the accident, in the period 1991-1995, the thyroid cancer relative risk was significantly increased (RR 3.91; 95 % CI: 1.27-10.29, p=0.01) in the highest dose category, compared to the lowest (although based on a small number of cases). For the age group 0-9 years at the time of the accident, a tendency of increased RR in the highest dose category appeared in the most recent period, 2011-2015. Our observations need to be confirmed by further following trends of thyroid cancer incidence in the cohort of 0-19-year-old Lithuanians at the time of the Chernobyl accident.
在过去的三十年中，全世界范围内以及立陶宛的甲状腺癌发病率都有所上升。尽管这种上升与过度诊断有关，但生活方式和环境因素的作用，包括接触电离辐射，也不能排除。在我们的回顾性研究中，我们旨在评估由于切尔诺贝利放射性碘在立陶宛儿童和青少年时期的摄取而导致的平均年龄特异性甲状腺剂量与 1991 年至 2015 年不同地区甲状腺癌发病率的趋势之间的关联。根据从草中可用的 I 活动测量值重建的牛奶中的放射性碘活性，为每个直辖市估计了依赖年龄的甲状腺剂量。为总人口和两个暴露年龄组（0-19 岁和 0-9 岁）计算了甲状腺癌发病率。对于三个特定于直辖市的甲状腺剂量（对于 0 岁婴儿）类别，估计了甲状腺癌相对风险（RR）：小于 100 mGy（参考组），100-199 mGy 和≥200 mGy。在研究期间（1991-2015 年），整个立陶宛人口共登记了 5664 例甲状腺癌病例；817 例发生在切尔诺贝利事故发生时年龄在 0 至 19 岁之间的年龄组中，266 例发生在年龄在 0 至 9 岁之间的年龄组中。自 2000 年以来，年龄标准化的甲状腺癌发病率显著增加，在 2009 年达到高峰（尤其是女性），然后略有下降并稳定下来。估计的平均年龄特异性甲状腺剂量因立陶宛西部的 270 mGy 到立陶宛中部和北部的 1.5 mGy 而有所不同。对于在事故发生时年龄在 0-19 岁之间的年龄组，在 1991-1995 年期间，与最低剂量组相比，最高剂量组的甲状腺癌相对风险显着增加（RR 3.91；95%CI：1.27-10.29，p=0.01）（尽管基于少数病例）。对于在事故发生时年龄在 0-9 岁之间的年龄组，在最近的 2011-2015 年期间，最高剂量组的 RR 呈增加趋势。我们的观察结果需要通过进一步跟踪切尔诺贝利事故时 0-19 岁的立陶宛人群的甲状腺癌发病率趋势来证实。
