[Comparison of Clinical Characteristics and Cytogenetic Abnormalities Between Myelodysplastic Syndromes in Nagasaki Atomic Bomb Survivors and Therapy-Related Myelodysplastic Syndromes].

BACKGROUND:Myelodysplastic syndromes (MDS) are classified into de novo and secondary forms. MDS among atomic bomb survivors (A-bomb-related MDS) is considered radiation-associated secondary MDS, whereas therapy-related MDS (t-MDS) develops after cytotoxic therapy and generally has a poor prognosis. However, differences between these two secondary MDS entities remain unclear. METHODS:We analyzed patients registered in the Nagasaki MDS cohort who were diagnosed between January 1985 and December 2023. Sixty A-bomb-related MDS and 150 t-MDS cases were included. Clinical characteristics, IPSS-R risk categories, overall survival (OS), and cytogenetic abnormalities at diagnosis were compared. RESULTS:The distribution of IPSS-R risk and cytogenetic risk categories did not differ significantly between groups. Nevertheless, median OS was significantly longer in A-bomb-related MDS than in t-MDS (65 vs. 19 months). Cytogenetic profiling revealed different features between groups, including a significantly higher frequency of monosomy 7 in t-MDS and of balanced structural abnormalities in A-bomb-related MDS. Balanced structural abnormalities were not clearly associated with prognosis. CONCLUSIONS:Although both A-bomb-related MDS and t-MDS are both classified as secondary MDS, they showed distinct prognostic and cytogenetic features. These findings suggest that the two conditions represent clinically distinct entities with different pathophysiology.