The role of allogeneic stem cell transplantation in T-cell lymphoma.
T - and natural killer (NK) cell neoplasms are a heterogeneous group of rare diseases with often inferior outcome. Only few studies exist, clarifying the role of allogeneic transplantation in different clinical scenarios. Larger prospective randomized studies are largely missing even for the more frequent entities. Mostly retrospective analysis and anecdotal reports of patients with advanced disease are available, hampering direct conclusions on the significance of allogeneic stem cell transplantation (alloSCT). Looking at recent data for T and NK cell neoplasm, it becomes evident that advances in donor search and availability of alternative stem cell sources as haploidentical or mismatched donors in addition to substantial improvements in graft-versus-host-disease prophylaxis reduce treatment-related mortality in alloSCT. The time point of transplantation has been described in a number of studies to be critically impacting outcome results as patients with advanced, chemorefractory disease often profit much less from alloSCT. Allogeneic transplantation offers a treatment option that can induce long-term remissions even in the relapsed setting. Many patients do not reach transplantation though because of chemorefractory disease and efforts should be made to bring more patients to transplantation earlier in the course of disease.