Treatment Outcome of Extended Involved-Field Intensity Modulated Radiation Therapy for Early Stage Extranodal Nasal-Type NK/T-Cell Lymphoma in the Era of Modern Chemotherapy

Abstract

This study aimed to evaluate the role of extended involved-field intensity modulated radiation therapy (IMRT) for patients with early stage extranodal nasal-type NK/T-cell lymphoma (NKTCL) who received new regimens chemotherapy. Between 2007 and 2016, 165 patients with early stage NKTCL underwent definitive high-dose and extended involved-field IMRT with (n = 158, 95.8%) or without chemotherapy (n = 7, 4.2%). One hundred forty patients (84.8%) received radiation dose more than 50 Gy to the primary tumor, whereas only 25 patients (15.2%) received less than 50 Gy. The majority of patients (n = 157, 89.1%) were treated with L-asparaginase–based regimens CT，whereas only 11 (6.7%) patients with doxorubicin-based CHOP/CHOP-like regimens. One hundred and nine patients (66.1%) received more than four cycles of chemotherapy. The locoregional control (LRC), overall survival (OS), and progression-free survival (PFS) were calculated using the Kaplan-Meier method. The 5-year OS, LRC, and PFS of all patients were 74.2%, 84.4%, and 72.5%. Patients who received ≥ 50 Gy had significantly higher LRC than those with <50 Gy, with 5-year LRC of 91.8% and 39.7% (P<0.001). The 5-year OS for patients without any risk factors (age >60, Elevated LDH, ECOG ≥2, primary tumor invasion [PTI] and stage II disease, defined as low-risk group) were 94.2%, whereas it was only 68.1% (P = 0.002) for patients with any risk factors (high-risk group). For high-risk early stage group, patients who received more than 4 cycles of chemotherapy significantly improved outcomes. The 5-year OS and PFS rates were 71.3% and 70.4% for patients with ≥4 cycles chemotherapy, compared with 59.5% (P = 0.032) and 54.4% (P = 0.009) for those with <4 cycles chemotherapy respectively. In multivariate analysis, ECOG ≥2, PTI, and Ann Arbor stage II were associated with poor OS. ECOG ≥2 and PTI were associated with increased risk of locoregional recurrence; whereas ECOG ≥2, PTI, primary site outside nasal cavity were associated with increased risk of PFS. In the modern era of IMRT and L-asparaginase–based chemotherapy, High-dose and extended-involved field IMRT for patients with early stage NKTCL achieved favorable outcomes. High-risk early stage patients who received more than 4 cycles chemotherapy had significantly improved OS and PFS.