Kim Bong-Kyu, Kim Jung-Min, Kim Myoung-Hee, Paek Do-Myung, Hwang Seung-Sik, Ha Mi-Na, Ju Young-Su
1Department of Occupational & Environmental Medicine, Hallym University Sacred Heart Hospital, Anyang, South Korea.
2Department of Environmental Health Sciences, Graduate School of Public Health, Seoul National University, Seoul, South Korea.
Ann Occup Environ Med. 2018 Apr 10;30:21. doi: 10.1186/s40557-018-0233-0. eCollection 2018.
The Korea Radiation Effect & Epidemiology Cohort - The resident cohort (KREEC-R) study concluded that there is no epidemiological or causal evidence supporting any increase in cancer risks resulting from radiation from Korean nuclear power plants (NPPs). But the risks of thyroid cancer in women were significantly higher in residents living near NPPs than control. Debate about the cause of the pattern of thyroid cancer incidence in women is ongoing and some researchers argue that detection bias influenced the result of KREEC-R study. Therefore there was a need to investigate whether residents living near NPPs who were assessed in the KREEC-R were actually tested more often for thyroid cancer. We evaluated the possibility of detection bias in the finding of the KREEC-R study based on materials available at this time.
Using the KREEC-R raw data, we calculated age standardized rates (ASRs) of female thyroid cancer and re-analyzed the results of survey on the use of medical services. We also marked the administrative districts of residents who received the Radiation Health Research Institute (RHRI) health examinations and those in which thyroid cancer case occurred as per the Chonnam National University Research Institute of Medical Sciences (RIMS) final report on maps where the locations of NPPs and 5 km-radii around them were also indicated. And we compared the incidence rates of Radiation-induced cancer measured between the first period when RHRI health examinations were not yet implemented, and the second period when the RHRI health examinations were implemented.
The ASR for the far-distance group, which comprised residents living in areas outside the 30 km radius of the NPPs, increased rapidly after 2000; however, that of the exposed group, which comprised residents living within a 5 km radius of the NPPs, started to increase rapidly even before 1995. The frequencies of the use of medical services were significantly higher in the intermediate proximate group, which comprised residents living within a 5-30 km radius of the NPPs, than in the exposed group in women. In case of female thyroid cancer, the second period ASR was higher than the first period ASR, but in case of female liver cancer and female stomach cancer no significant difference were observed between the periods. On map, many administrative districts of residents who received RHRI health examinations and most administrative districts in which thyroid cancer case occurred on RIMS final report were outside 5 km-radii around NPPs.
We could not find any evidence supporting the assertion that detection bias influenced the increased risks of female thyroid cancer observed in the exposed group of the KREEC-R study, as opposed to the control group.
韩国辐射效应与流行病学队列——居民队列（KREEC - R）研究得出结论，没有流行病学或因果证据支持韩国核电站辐射会导致癌症风险增加。但核电站附近居民中女性患甲状腺癌的风险显著高于对照组。关于女性甲状腺癌发病率模式的原因的争论仍在继续，一些研究人员认为检测偏倚影响了KREEC - R研究的结果。因此，有必要调查在KREEC - R中接受评估的核电站附近居民是否实际上更频繁地接受了甲状腺癌检测。我们根据目前可得的资料评估了KREEC - R研究结果中检测偏倚的可能性。
利用KREEC - R原始数据，我们计算了女性甲状腺癌的年龄标准化率（ASR），并重新分析了医疗服务使用情况的调查结果。我们还在地图上标注了接受辐射健康研究所（RHRI）健康检查的居民所在行政区以及根据全南国立大学医学科学研究所（RIMS）最终报告甲状腺癌病例所在的行政区，地图上还标明了核电站的位置及其周围5公里半径范围。并且我们比较了在RHRI健康检查尚未实施的第一阶段和实施RHRI健康检查的第二阶段之间测量的辐射诱发癌症的发病率。
由居住在核电站半径30公里以外地区的居民组成的远距离组的ASR在2000年后迅速上升；然而，由居住在核电站半径5公里以内的居民组成的暴露组的ASR甚至在1995年之前就开始迅速上升。在女性中，由居住在核电站半径5 - 30公里范围内的居民组成的中近距离组使用医疗服务的频率显著高于暴露组。就女性甲状腺癌而言，第二阶段的ASR高于第一阶段的ASR，但就女性肝癌和女性胃癌而言，两个阶段之间未观察到显著差异。在地图上，接受RHRI健康检查的居民的许多行政区以及RIMS最终报告中甲状腺癌病例所在的大多数行政区都在核电站周围5公里半径范围之外。
我们找不到任何证据支持检测偏倚影响了KREEC - R研究暴露组（与对照组相比）中观察到的女性甲状腺癌风险增加这一说法。
