Cox regression analysis of overall mortality, PFS, TRM, relapse or progression and acute or chronic GVHD between non-myeloablative and ablative conditioning regimens are shown in Table 4 . When adjusted for patient and donor factors, non-myeloablative conditioning resulted in significantly lower overall mortality HR 0.40 (0.3 --0.6), improved PFS HR 0.55 (0.4 --0.8) and much lower TRM HR 0.22 (0.1 --0.4). The risks of acute GVHD grades 2 --4 were also significantly lower with non-myeloablative regimens HR 0.41 (0.3 --0.6). The risks of relapse or progression and chronic GVHD when adjusted for competing risks of death and patient and donor factors, were not significantly different between ablative and non-ablative conditioning, despite the almost exclusive use of PBSC for the non ablative recipients.