Epidemiology of Myelodysplastic Syndromes in Atomic Bomb Survivors

[背景]骨髓增生异常综合征(MDS)是一种获得性克隆性干细胞疾病，其特征是无效的造血和高进展为白血病的风险。MDS的病因仍不清楚。[目的]探讨辐射暴露与原子弹幸存者发生MDS风险的关系。[方法]回顾收集长崎市5所医院的MDS病例，通过与长崎大学科学数据中心的长崎原子弹幸存者数据库的链接，对长崎原子弹幸存者进行鉴定。通过骨髓涂片镜检和临床资料进行疾病确认。在回溯性队列分析中，我们设定了1980年活着但没有MDS的原子弹幸存者的回溯性队列。在年龄调整的人口分析中，我们利用地级人口的官方统计数据，比较了原子弹幸存者和非原子弹幸存者之间的MDS发病率。[结果]到目前为止，我们积累了1970年代至2004年间确诊的约600例MDS病例，确定了约200例原子弹幸存者。在回溯性队列分析中，在1980年至2004年的87496名幸存者中发现了162例MDS(粗发病率：10.7/103PY)。男性发生MDS的风险高于女性(RR=1.7)，距离震中1.5公里以内的幸存者比距震中3.0公里以上的幸存者(RR=4.3)高。在1.5公里内暴露的幸存者中，与RA和RARS亚型相比，RAEB和RAEB-t亚型的风险较高。在年龄调整的人群分析中，原子弹幸存者的MDS粗发病率高于非原子弹幸存者(粗发病率：10.0/106Py比6.49/106Py，RR=1.5)。[讨论]结果表明，辐射暴露与MDS的风险之间存在明显的关联。需要进行辐射剂量分析来证实这种联系。

[Background] Myelodysplastic syndromes (MDS) are acquired clonal stem cell disorders characterized by ineffective hematopoiesis and a high risk of progression to leukemia. Etiologies of MDS are still unknown. So far, there is no large-scale epidemiological study for population exposed to radiation.[Aim] To investigate the association between radiation exposure and a risk of MDS in Atomic bomb survivors.[Methods] Overall MDS cases were retrospectively accumulated from five hospitals in Nagasaki City and then identified Atomic bomb survivors by linkage with the Database of Nagasaki Atomic Bomb Survivors in the Scientific Data Center at Nagasaki University. Disease confirmation was conducted with the microscopic examination of bone marrow smear and clinical data. In retrospective cohort analyses, we set a retrospective cohort of Atomic bomb survivors who were alive at 1980.1.1 but no MDS. In age-adjusted population analyses, we used official prefecture population statistics and then compared MDS incidence between Atomic bomb survivors and Non-Atomic bomb survivors.[Results] Up to now, we accumulated approximately 600 MDS cases diagnosed during 1970' to 2004, and identified around 200 cases who were Atomic bomb survivors. In retrospective cohort analyses, 162 MDS were identified among a cohort of 87496 survivors during 1980 to 2004 (crude incidence rate: 10.7 per 103 PY). Risk of MDS was high in male than female (RR=1.7), in survivors exposed within 1.5km from hypocenter than those over 3.0km (RR=4.3). Risk of subtypes of RAEB ＆ RAEB-t was high compared with subtypes of RA ＆ RARS among survivors exposed within 1.5km. In age-adjusted population analyses, crude incidence rate of MDS was higher in Atomic bomb survivors than Non-Atomic bomb survivors (crude incidence rate: 10.0 vs. 6.49 per 106 PY, RR=1.5).[Discussion] Results suggest a clear association between radiation exposure and a risk of MDS. Radiation dose analysis is needed to confirm this association.