Allogeneic haematopoietic stem cell transplantation as a promising treatment for natural killer-cell neoplasms

The efficacy of allogeneic haematopoietic stem-cell transplantation (allo-HSCT) for natural killer (NK)-cell neoplasms is unknown. We investigated the results of allo-HSCT for NK-cell neoplasms between 1990 and 2003 through questionnaires. After reclassification by a haematopathologist, of 345 patients who underwent allo-HSCT for malignant lymphoma, 28 had NK-cell neoplasms (World Health Organization classification): extranodal NK/T-cell lymphoma (n = 22), blastic NK-cell lymphoma (n = 3), and aggressive NK-cell leukaemia (n = 3). Twelve were chemosensitive and 16 chemorefractory. Twenty-two had matched-related donors. Stem-cell source was bone marrow in eight and mobilised peripheral blood in 20. Conditioning regimens were myeloablative (n = 23) and non-myeloablative (n = 5). Grade 2-4 acute graft-versus-host disease (GVHD) and chronic GVHD developed in 12 and 8 respectively. Eight died of disease progression, three of infection, two of acute GVHD, one of veno-occlusive disease, one of interstitial pneumonitis, and one of thrombotic microangiopathy. Two-year progression-free and overall survivals were 34% and 40% respectively (median follow-up, 34 months). All patients who did not relapse/progress within 10 months achieved progression-free survival (PFS) during the follow-up. In multivariate analysis, stem cell source (BM versus peripheral blood; relative risk 3.03), age (>= 40 years vs. < 40 years; relative risk 2.85), and diagnoses (extranodal NK/T-cell lymphoma versus others; relative risk 3.94) significantly affected PFS. Allo-HSCT is a promising treatment for NK-cell neoplasms.