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.