The effectiveness of busulfan-based conditioning regimens for stem cell transplantation against lymphomas in children, adolescents, and young adults in Japan

Conditioning regimens for stem cell transplantation (SCT) involving total body irradiation (TBI) are generally preferred over busulfan (BU)-based ones for lymphoid malignancies. However, reports of favorable results using BU against lymphomas have recently emerged. This study sought to compare the effectiveness of BU and TBI regimens for SCT against lymphomas. We retrospectively analyzed 893 lymphoma patients who underwent primary SCT in Japan between 1980 and 2015. The median age of all patients was 18 years (range, 0-30 years) with 589 males, 303 females, and 1 patient whose sex was unknown. Overall survival (OS) was not different between those receiving BU and TBI (P = 0.672). OS in patients receiving autologous SCT was significantly better with BU over TBI regimens (P = 0.038), particularly in children (0-15 years) (P = 0.024). Conversely, OS in adolescents and young adults (AYAs; 16-30 years) receiving allogeneic SCT was significantly worse with BU over TBI regimens (P = 0.035). Overall, BU regiments had comparable effectiveness to TBI conditioning regimens, and, although less effective for AYAs with allogeneic SCT, were particularly more effective than TBI regimens for children who received autologous SCT.