Risk stratification in extranodal natural killer/T-cell lymphoma

Extranodal natural killer/T-cell lymphoma (ENKL), a subtype of natural killer/T-cell malignancies, is a rare subset of lymphomas with significant biological and clinical heterogeneity. The prognosis of ENKL is variable and therapeutic approaches are not well established. The optimal dose, combination, and sequence of radiotherapy and chemotherapy are evolving, as is the role of stem cell transplantation. Radiotherapy is an essential component of therapy for early-stage disease. The clinical course of advanced disease is highly aggressive, with frequent chemotherapy resistance and a poor prognosis. For relapsed disease, asparaginase-based regimens have provided encouraging results and are currently under investigation in the frontline setting. Our article discusses the key aspects of biology, pathogenesis and clinical presentation that contribute to the heterogeneity, and proposes a stratified approach to the treatment of ENKL based on clinical, pathologic and biologic risk factors. Although considerable advances have been made in our understanding of the biology and prognosis of this lymphoma, it remains critical that all patients with a diagnosis of ENKL are enrolled and treated in clinical trials so that optimal therapies can be identified.

Extranodal natural killer/T-cell lymphoma: current concepts in biology and treatment

Natural killer/T-cell (NK/T) lymphomas represent a group of rare tumors of NK and NK-T cells. The World Health Organization classifies NK-cell tumors into three types, extranodal NK/T-cell lymphomas (ENKL, nasal and non-nasal), NK-cell leukemias, and a blastic variant (CD4-positive, CD56-positive hematodermic neoplasms). We focus our review to the current concepts in biology and treatment of ENKL. Though considerable advances have been made in our understanding of NK-cell biology, malignant transformation including the role of Epstein-Barr virus, and prognosis, the rare nature of ENKL and its heterogeneity limit the ability to standardize therapy. Radiotherapy is fundamental to treatment of early-stage disease with a role for chemoradiotherapy among high-risk patients. The clinical course of advanced disease is highly aggressive with frequent chemotherapy resistance and a poor prognosis. Therapeutic approaches to advanced-stage or relapsed and refractory disease, including the appropriate sequence of chemotherapy, combined modality therapy, and stem cell transplantation is not well-established. International and multicenter clinical trials are needed for this rare and aggressive disease.