Risk Factors Influencing Survival in T‐Cell Lymphoblastic Lymphoma and T‐Cell Acute Lymphoblastic Leukemia

Background T‐cell lymphoblastic lymphoma (T‐ LBL ) is a rare non‐Hodgkin lymphoma. The World Health Organization defines T‐ LBL and T‐cell acute lymphoblastic leukemia (T‐ ALL ) as the same entity. However, the clinical variations between them result in divergent treatment outcomes. Objectives The aim of this study was to compare the outcomes of patients with T‐LBL and T‐ALL and identify ideal candidates for autologous hematopoietic stem cell transplantation (auto‐HSCT) or allogeneic hematopoietic stem cell transplantation (allo‐HSCT). Study Design This retrospective analysis included 148 patients diagnosed with T‐LBL (67 [45.3%]) or T‐ALL (81 [54.7%]) between November 2009 and December 2022 in seven hospitals in the Republic of Korea. Overall survival (OS) and progression‐free survival (PFS) were analyzed using the Kaplan–Meier method, and allo‐HSCT, auto‐HSCT, and chemotherapy‐only treatment modalities were compared. Cox proportional hazards models were used to identify risk factors for survival, and survival decision trees were used for risk stratification. Results The median follow‐up duration was 60 months. The 5‐year OS rates were 43.5% and 52.8% in the T‐LBL and T‐ALL groups, respectively ( p = 0.111). The T‐LBL group had lower PFS than the T‐ALL group ( p < 0.001). The 5‐year OS rates for allo‐HSCT, auto‐HSCT, and chemotherapy‐only were 62.8%, 62.4%, and 13%, respectively. Two or more extranodal sites, large masses > 6 cm, axial bone involvement, and non‐complete remission after chemotherapy were poor prognostic factors for OS. Conclusions In this multicenter retrospective analysis, hematopoietic stem‐cell transplantation (allo‐ or auto‐HSCT) was associated with better survival than chemotherapy alone. For T‐LBL, an exploratory signal from our prognostic model suggests that selected high‐risk patients may be considered for upfront allo‐HSCT. However, overall survival was comparable between allo‐ and auto‐HSCT in this cohort, and durable outcomes after transplant were largely observed in patients who achieved complete remission. These findings are hypothesis‐generating and support individualized, response‐adapted strategies that warrant prospective validation.