Extranodal Natural Killer (NK)/T-Cell Lymphoma, Nasal Type

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTCL) is an aggressive malignancy of mature T- and natural killer cells characterized by its association with Epstein–Barr virus and majority extranodal upper aerodigestive tract involvement. 70–90% patients present with localized disease at diagnosis. Initial evaluation requires PET/CT, MRI, fiberoptic endoscopy and quantification of circulating EBV DNA. Stage, risk stratification and primary site provide essential information and frame in estimating the prognosis and determining treatment plan. Based mainly on the results of phase II studies and retrospective analyses, a risk-adapted combined modality treatment strategy is recommended. In early-stage disease, radiotherapy is the backbone of curative treatment. Radiotherapy alone is a viable option for low-risk localized patients and for fragile or elder patients who could not tolerate chemotherapy. Combined modality treatment (radiotherapy and chemotherapy) is recommended for intermediate- to high-risk localized patients. Non-ANT-based chemotherapy, including L-asparaginase and platinum, with or without radiotherapy is the primary treatment for advanced-stage patients. High dosage (≥50 Gy) and adequate coverage of the primary tumor and potential subclinical extent of involvement constitute the principles of radiotherapy in ENKTCLs. The extended involved-site radiotherapy (E-ISRT) principles are advocated. After completion of treatment, a risk-dependent time-varying surveillance plan is recommended.