High-dose chemotherapy and hematopoietic SCT in the management of natural killer-cell malignancies.

Natural killer (NK)-cell lymphomas are aggressive. Patients with early (stage I/II) diseases respond favorably to radiotherapy and chemotherapy. Patients with relapses and advanced (stage III/IV) diseases have poor outcome. To improve treatment results, high-dose chemotherapy with hematopoietic SCT (HSCT) has been performed. A review of 57 published cases of autologous HSCT showed the status pre-HSCT as the only significant prognostic factor. HSCT at CR had the best survival. As patients achieving CR with chemotherapy and radiotherapy also have favorable outcome, a definite advantage of autologous HSCT cannot be established. Patients with advanced, relapsed or refractory diseases had dismal survivals after autologous HSCT. Allogeneic HSCT had been reported in about 30 patients, with a 2-year OS of 40%. To evaluate the efficacy of allogeneic HSCT, optimal conditioning regimens and a clear graft-versus-lymphoma effect should be defined. Furthermore, clinicopathological characteristics predicting benefits from allogeneic HSCT need to be determined. HSCT is a potential option in NK-cell lymphoma. However, autologous HSCT may not be necessary for good-risk patients in CR. Whether poor risk patients will have improved outcome with autologous HSCT remains to be defined. The role of allogeneic HSCT requires more rigorous future studies.