Clinical outcomes of modified busulfan plus cyclophosphamide versus total body irradiation plus cyclophosphamide for T-cell acute lymphoblastic leukemia/lymphoma.

T-cell acute lymphoblastic leukemia/lymphoblastic lymphoma (T-ALL/LBL) remains a challenging malignancy with poor prognosis. Allogeneic hematopoietic stem cell transplantation (allo-HCT) remains a key curative option, but the optimal conditioning regimen is unclear. We retrospectively analyzed 93 T-ALL/LBL patients undergoing allo-HCT between January 2010 and July 2023, including 72 with modified busulfan plus cyclophosphamide (mBuCy) and 21 with total body irradiation plus cyclophosphamide (TBI-Cy). Propensity score matching (PSM) was applied to adjust baseline differences. Prior to PSM, survival outcomes were not significantly different, though numerical trends favored TBI-Cy. After PSM, 3-year graft-versus-host disease-free, relapse-free survival (GRFS) was higher with TBI-Cy (52% vs. 22%; p = 0.036), while other endpoints remained comparable in terms of statistical significance. Among patients transplanted in first complete remission (CR1), outcomes were not significantly different between regimens. These findings suggest TBI-Cy may provide improved composite outcomes, mainly reflected by GRFS, and inform conditioning regimen selection in T-ALL/LBL.