Efficacy of extended-field intensity-modulated radiotherapy for early-stage NK/T cell lymphoma

Abstract

Objective To evaluate the efficacy of extended-field intensity-modulated radiotherapy (IMRT) in the treatment of patients with early-stage NK/T cell lymphoma (NKTCL), and to examine the clinical characteristics and the effect of treatment factors on the prognosis of these patients. Methods The clinical data of 165 patients with early-stage NKTCL who underwent extended-field IMRT with (n=158, 95.8%) or without chemotherapy (n=7, 4.2%) were reviewed. Of these 165 patients, 140(84.8%) received a radiation dose of ≥50 Gy to the primary lesion, and 25 patients (15.2%) received a radiation dose of<50 Gy. Most patients (n=147, 89.1%) were treated with L-asparaginase-based chemotherapy regimens, whereas only 11 patients (6.7%) were treated with doxorubicin-based CHOP/CHOP-like regimens. In addition, 109 patients (66.1%) received ≥4 cycles of chemotherapy. Locoregional control (LRC), overall survival (OS), and progression-free survival (PFS) rates were calculated using the Kaplan-Meier method, and the log-rank test was used for survival comparison and univariate prognostic analysis. A multivariate prognostic analysis was performed using the Cox model. Results The 5-year sample size 55.The 5-year OS, PFS, and LRC rates of all patients were 74.2%, 72.5%, 84.4%, respectively. The patients who received a dose of ≥50 Gy had a significantly higher 5-year LRC rate than those with<50 Gy (91.8% vs. 39.7%, P=0.000). The 5-year OS was significantly higher in the low-risk early-stage group than in the high-risk early-stage group (P=0.002). For the high-risk early-stage NKTCL group, patients who received ≥4 cycles of chemotherapy had significantly higher 5-year OS and PFS than those who received<4 cycles of chemotherapy (5-year OS: 71.3% vs. 59.5%, P=0.032; 5-year PFS: 70.4% vs. 54.4%, P=0.009). In addition, multivariate analysis showed that ECOG≥2, primary tumor invasion (PTI), and Ann Arbor stage Ⅱ were associated with poor OS (P=0.006, 0.002, 0.014), and ECOG≥2 and PTI were associated with reduced LRC (P=0.004, 0.016). Furthermore, ECOG≥2, PTI, Ann Arbor stage Ⅱ, and extranasal primary site were associated with lower PFS (P=0.045, 0.003, 0.030, 0.032). Conclusions Extended-field IMRT at a dose of ≥50 Gy can lead to favorable LRC, OS, and PFS in patients with early-stage NKTCL.However, it is less effective against distant early-stage NKTCL in patients with poor prognosis. Nevertheless, ≥4 cycles of chemotherapy can significantly improve the OS and PFS of patients with early-stage NKTCL. Key words: NK/T-cell lymphoma/radiotherapy; Radiotherapy, intensity-modulated; Prognosis