Background: Extranodal natural killer/T-cell lymphoma (ENKTL), nasal-type is highly aggressive with rather poor prognosis. Combined chemoradiotherapy is necessary for those having fever and/or extensive lesions. It is imperative to develop an effective chemotherapy regimen as ENKTL is often refractory to CHOP. This study was conducted to evaluate the efficacy and safety profiles of gemcitabine, dexamethasone, and cisplatin (GDP) as initial treatment combined with radiotherapy for patients with stage IE/IIE ENKTL. Methods: This study was conducted of "sandwich" protocols, with earlier involved-field radiotherapy after an initial 2 cycles of GDP, followed by further "consolidation" 2 to 4 cycles. Patients, newly diagnosed stage IE/IIE ENKTL, having fever and/or extensive lesions were enrolled. The primary endpoints were objective response rate (ORR) and complete remission (CR) rate after initial chemotherapy and whole treatment. The secondary endpoints were 2-year overall survival (OS), 2-year progression-free survival (PFS), and toxicity. Results: Seventy-two patients completed initial GDP chemotherapy, which resulted in 91.7% ORR that included 22 patients (30.6%) with CR and 44 patients (61.1%) with partial response. 35 of 41 patients having B symptom got fever remission after chemotherapy. After whole treatment completion, CR rate was 81.9% (59/72) and ORR was 91.7% (66/72). 6 patients died during RT due to disease progression or complication of hemophagocytic syndrome. With a median follow-up of 22 months, the 2-year OS was 84.6% (95%CI, 80.3% to 88.9%), and the 2-year PFS was 81.6% (95%CI, 76.6% to 86.6%). Patients with CR after RT had better prognosis than their counterparts. The major adverse events were myelosuppression, liver dysfunction, gemcitabine-related skin rash and digestive tract toxicities. Grade 3 to 4 neutropenia and thrombocytopenia were18.0% and15.3%, respectively. Conclusions: The research showed that the “sandwich” protocol of GDP combined with RT was effective treatment for newly diagnosed ENKTL, especially for those having fever and/or extensive lesions.