Radiotherapy for extramedullary leukaemic manifestation (Chloroma)

Extramedullary leukaemic disease (EMD, synonym chloroma) is a rare solid manifestation of myeloid leukaemia for which the value of radiotherapy (RT) as a treatment strategy remains controversial. The aim of this study is to analyse the effectiveness of various RT doses for EMD in the modern treatment era. Between January 2000 and June 2016, 20 patients with total of 45 lesions underwent RT for EMD at our institution. With a median radiation dose of 26 Gy (range 4-42 Gy), local remission could be achieved in 91% of patients (complete remission rate: 71%). The median duration of local control (DOLC) was 17 months (95% confidence interval [CI] 0.5-33) and the median overall survival (OS) after chloroma onset was 24 months (95% CI 11-38). No noticeable difference between high- and low-dose regimens has been observed (74% versus 68%; P = 0.5). In the multivariate analysis, only Eastern Cooperative Oncology Group (ECOG) score and bone marrow state during RT have proven to be determinant for durable local control and OS. Low-dose RT (≤26 Gy) achieves good local control compared to high-dose regimes. Bone marrow state during RT and ECOG score during RT may play a crucial role, influencing both DOLC and OS. (orig.)