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.