Epidemiology of Myelodysplastic Syndromes in Atomic Bomb Survivors

骨髓增生异常综合征（Myelodysplastic syndrome，MDS）是一种获得性克隆性干细胞疾病，以造血功能低下为特征，具有发展为白血病的高风险。MDS的病因仍然未知。到目前为止，还没有对受辐射人群进行大规模的流行病学研究。[Aim]研究原子弹爆炸幸存者辐射暴露与MDS风险之间的关系。[方法]回顾性收集长崎市5家医院的MDS病例，并与长崎大学科学数据中心的长崎原子弹幸存者数据库进行链接，确定原子弹幸存者。通过骨髓涂片镜检和临床资料进行疾病确认。在回顾性队列分析中，我们对1980年1月1日存活但无MDS的原子弹爆炸幸存者进行了回顾性队列分析。在年龄调整的人口分析中，我们使用官方的县人口统计数据，然后比较原子弹爆炸幸存者和非原子弹爆炸幸存者之间的MDS发病率。[结果] 1970 ~ 2004年累计确诊MDS病例约600例，其中原子弹爆炸幸存者约200例。在回顾性队列分析中，在1980年至2004年期间，在87496名幸存者的队列中确定了162例MDS（粗发病率：10.7/103 PY）。男性MDS发病危险性高于女性（RR=1.7），距震源1.5km以内的幸存者MDS发病危险性高于3.0km以上的幸存者（RR=4.3）。在1.5km范围内暴露的幸存者中，RAEB和RAEB-t亚型的风险高于RA和RARS亚型。在年龄校正的人群分析中，原子弹幸存者中MDS的粗发病率高于非原子弹幸存者（粗发病率：10.0 vs. 6.49/106 PY，RR=1.5）。[讨论]结果表明辐射暴露与MDS风险之间存在明确的相关性。需要进行辐射剂量分析来证实这种关联。

[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.