Abstract
PURPOSE: This study aimed to assess the treatment outcomes, toxicity, and potential prognostic factors in patients with early-stage extranodal natural killer/T-cell lymphoma treated with radiation therapy combined with chemotherapy. METHODS AND MATERIALS: One hundred eighteen patients with stage I/II extranodal natural killer/T-cell lymphoma who were treated with radiation therapy combined with chemotherapy were retrospectively analyzed between July 2003 and January 2019. The median dose was 50 Gy (Range, 45-61.2 Gy). The Kaplan-Meier method was used to calculate progression-free survival and overall survival. The patients were scored according to their prognostic indices. RESULTS: The overall and complete response rates were 93.2% and 82.2%, respectively. At a median follow-up of 43 months, the 5-year overall survival and progression-free survival rates were 73.9% and 68.4%, respectively. Adverse events of grade 3 or higher were observed in 20 patients (16.9%). Patients with primary disease in the Waldeyer's ring had poorer survival (P = .015). Compared with anthracycline-based regimens, non-anthracycline-based regimens significantly improved the 5-year overall survival (76.6% vs 54.8%, P = .027) and progression-free survival (72.4% vs 53.1%, P = .013). After treatment, the 5-year overall survival rate was 78.6% in complete response patients versus 44.9% in noncomplete response patients (P = .003). For patients with low- and intermediate-low-risk according to the nomogram-revised risk index model, the complete response rate was 100%. When primary lesion data were added to the nomogram-revised risk index as the basis for another prognostic index (modified nomogram-revised risk index), the low-risk (0 to 2 risk factors) and high-risk (3 or more risk factors) categories were noted (84.2% vs 62.2%, P = .036). CONCLUSIONS: Patients with early-stage extranodal natural killer/T-cell lymphoma had high response rates and favorable survival rates with radiation therapy and non-anthracycline-based chemotherapy regimens. Patients who achieved complete response had better survival than those who did not. The extranodal natural killer/T-cell lymphoma-specific prognostic models may require further optimization.